36267485 Metalworking Handbook - [PDF Document] (2024)

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A project of Volun:eers in Asia

Metalworking Handbook: Princiales and Procedures

by: Jeannette T. Adams

Published by: Arco Publishing, Inc. 215 Park Avenue South New York, NY 10003 USA

Paper copies are $12.95.

Available from: AL-CO Publishing, Inc. 215 Park Avenue South New York, NY 10003 USA

Reproduced by permission of Arco Publishing, Inc.

Reproduction of this microfiche document in any form is subject to the same restrictions as those of the original document.

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219 Park Avenue South, New York, N.Y~ 10003

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The author dsires to dO0d3ige with thanks the assistance of the following national organizations and branches of thr government that haw cooperated in the production. of this book.

,\luminum Com;xmy of .4merica, .4merican Brass CII., :Imerican Steel &x \iire Co.. .4rmstrong Manufac- tl:rivg Co.. Black A Ijerker !xlfg. Co., Brown & Sharpe \Ifg, Co.. Carborrmdum Co.. Carpenter Steel Co., Cin- (,inriati Rickford Tool Co.. Cincinnati Milling Machine CIl..Cincinnnti PlanrrCo..CincinnatiShaprrCo.,Clay- tnn&Lambrrt ~lfg.Co..ClevelandTwistDrillCo.,Cop- per &RI-ass Researchr\ssociation. Delta~;~Iannfacturing Division. Rockwell Sfanufarturinp Co., Desmond- Stephan Mfg. Co., Eugene Dietzen Co.. General Mo- tors Corp.. Cpometric Tool Co._ Division Greenfield Tap and Die Corp., Giddings & Lewis Machine Tool Co.. Henry Disston & Sons, Imperial Brass Mfg. Co,.,

Industrial Diamond Tool Co., Ingersoll-Rand Co., International Business Machines. Kester Solder Co., L. S. Starrett Co., Niagara Machine & Tool Works, Nicholson File Co., h’orton Co.,. Parker-Kalor Corp., Pratt & Whitney Division, N&s-Bement-Pond Co., Precision Truing IX, Rockwell Mfg. Corp., Ross Mfg. Co., South Bend i.athe Works, Standard Tool Cc., Stanley Electric Tools (Division of the Stanley Works), Stanley Tool Co., Taft-Pierce Co., University of the State of New York (Bureau of Vocational Curriculum Development). U.S. Navy Training Publications Cen- ter, Buxau of Navy Personnel, U.S. Steel Corp., War- ner & Swasey, William Sellers & Co.

The author is inctchttx: to the many teachers and supervisors who have expressed an interest in this book and \ikc, ’ we offered valuable opinions, com- ments, and ,tions.

Published by Arco Publishing Company, Inc. 219 Park Avenue South, New York, N.Y. 10003

Copyright @ 1976 by Jeannet:e T. Adams

All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission in writing from the publisher, except by a reviewer.

Library of Congress Catalog Card Number 75.23577 ISBN O-668-03857-8

Printed in the United States of America

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k P;-pe;t& of mat;;i&. 9: metals, il; ferrous metals, 11; irons. 11; plain steels, 12; allo\- steels. 12; nonferrous metals, 12; designations ad warkings, 14; continuous idcntifirotioo mad&g, 16; color marking, 17; identification of metals, 19; spark test, 20: acid test; 23: beat treatment, 23; hardness tests, 24; plastics, 28; machining opera- tioos. 20

2 easurisq Tools and How to Use Them . . . . . . . . . . . . . i<uh ;nd tapes, :31: measuring procedures, 32; care of rules and tapes, 34; calipers, 3-t; using calipus, :3.$; care of calipers, 37; slide calipers, 37; vernier caliper, 38; care c>f vernier calipers. ~2.; micrometers, 42; types of micrometers, 42; selecting the proper micrometer, 43; cnx of micrometers, 47; squares, 47; carpenters square, 47; try cqoare, 47; sliding T-bevel, 47; combination square, 48; care of squares, 48; miscel- laneoos gages, 50; depth gage, 50; surface gage, 51; surface plate, 52: care of surface plates, 53; thickness i feeler) gage, 53; care of thickness gages, 53; thread gage, 53; n-ire gage, .54; te!escopinggage, 55; sxall hole gage, 55; marking gages, 56; dividers, .56; plumb bob. 57; le\-els, s8

3 Metaiworking Hand Tools and How to Use Them . . . . . . . . . Classes of tooIs_ 60; hammers and mallets, 60; screwdrivers, 64; drills, 67; hacksaws and blades. 72; ciamps. 76; pliers and nippers, 77: wrenches, 79; cold chisels, 82; roofing and gutter tongs, seamers and beaders, 85; punches, 88: snips and shears, 89; stakes. 92; stakeholders, 94; files and filing procedures, 94; rivet sets, 100; hand gi-oovers. 100; soldering coppers, 100: firepots and blowtorches, 101; vises, 105; care of vises. 106: safety precautions. 106

achines. . . . . . . . . . . . . . I . Sq”ariog shears, 107; folding and bending machines, 118; bar folders, 118; procedures for basic bar folder operations, 122; sheet iron folders, 126; pipe folders, 129; brakes; 1:30; basic operating procedures of standard hand brakes, 131; combination folders and brakes, 135; drill press_ 136; portable electric hand drills, 142; forming machines, 14;: bench machines. 15”

5 eta1 . . . . . . . . . . . . . . . . . . . . Edges and seams. 162; procedures for making and finishing grooved seams, 164; Ranges. 168: wired and reinforced edges, 171; metal cutting operations, 179; metal cutting with &is&, 179; metal cutting with drills, 180; threads and thread cutting, 182: tap drill drtrrmination. 182; cutting machine threads with taps, 183; cutting machine tbrrads \vitb dies, 185; cutting internal pipe threads, 186; cutting external pipe tbrcw~s. 187; reaming operations, l&8; cutting piping and tubing, 189; bending and fiwiy ,~nrtallic tubing, 191; rwooving broken bolts and studs, 193; removing a broken tap fmn il Me, 195






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aterials and Procedures . . . V . . . . . . . Soldering procedures. 201

iveting aterials and Procedures . . . . . . . . . . . Rivet s&tin,: ~rorrdores. 2Od: riveting alwninnm and its alloys. 21 I; hand and ma- rbinc rivetlog inrtho Is. 215: pop rivets, 216; rivet selection, 218

eta1 Fasteners . . . . . . l . . . . . . . . . Sheet metal screws. 219: nails, 2?1; fasieners for copper sheet metal, 225; cleats for copper \rurk. 226: s?ecial ia:;teoers for metal gutters, leaders, and roof drainage svstems. 227: bolts. 233: capscrews; 234; setscrews, 234; nuts, 234; washers, 235; tieys and pins. 235: tomlock fasteners, 236; safetying methods, 237; safety wiring, 237

~~i~~g . . . . - . . . . . . . . . . . . . The lathe for metal spinning, 240; spinning procedures, 242; using special spinning chucks. 247

etalwo~~~g Power Tools . . . . . . . . . . . 1’ort:rble clectrir ower tools. grinders, 251; sa E

2.50; drills, 250; sanders, 251; disc sander, 251; portable er saxv; 251; electric impact wrench, 252; safety precautions, 252;

portable pneumatic power tools, 253; pneumatic chipping hammer, 253; needle and rotarb- impact scalers, 255; portable pneumatic impact wrench, 255; bench grinder, 256: safetx~ prerautions, 257

Luysut and Ben&work . . . . . . . . . . . . . . . . . . 258 \Icchanica! drawings and blueprints, 258: working from drawings, 258; accurate measuremmt. 258; limits of accuracy, 260; precautions, 261; layout, 261; layout methods. 262; laying out valve flange bolt holes. 266; benchwork, 269; assemble and disassembly, 269; precision work, 270; using hydraulic and arbor presses, 271; ‘using an orvacrtvlene torch, 271

Drills, D g. and D g Machines . . . . . . . . . . Drdling procedures, 273; checking the drill, 273; drilling small boles, 273; drilling large holes, 274; drilliilg sheet metal, 274; drilling round stock, 274; countersiokiog, 274; drilling for tapped holes, 274; miscellaneous drilling machine operations, 275; the radial drilling machine, 277: radial drilling machine operation, 278; drilling ma- chines. 281; :rositire drills. 281; standard drill press, 282; radial drills, 282; universal radial drills, 282; multiple spindle drill, 283; universal multiple spindle drill, 283; gang drills, 283; construction of a drill press. 284

achines. . . . . . . . . . . . . . . . . . Knee-and-colomo milling machines, 292; manufacturing milling machines, 292; size and po\ver rating of miEIing machines,~ 293; milling machine accessories, 294; milling cutters, 298; s?zndard milling cotters, 300

perating achines . . . . . . . . . . . . . . Setting up., 307: mounting of milling cutters, 309; types of mounting for mding cut- trrs. 31 I : t!mdament;rls c&f the milling process, 315; methods of milling, 316; selection of setop. 3lE: tnillin~ suriwes at compound angles on single-point +r&. 028; Mric&n and m;lintrn;mce procedures. 33.3

tools, 318: cutting


. . .

. . .

. . .

. . I

. . .

. . . 273

. . .

. . .









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Shapers . . . . . . . . . . . . . . . . . . . . . . . . 33. Vertir. I shapers. 335: horizontal shapers, 335; holding the work, 342

r Operations . . e . . . I . . . . . . General operating p’ , 348; universal tables, 351; operai L ,d 1 ‘justment of the automatic power down feed to the head, 351; tool lifter oper. “,&II, 3h. wxiiiary front cross feed operation. 353; adjnstnxnts, 353; lub:i:e’+, 360

Planers . . . . . . . . . . . m . . . . . . . . . . . q 363 Construction of a planer, 363; drive methods, 365; ,-A is and accessories, 365; planer operations. 377

g . . . . . . . . . m . . . . . . . . . . . . . . 380 The lath-. 380; before !-on start to work, 381; work-holding devices, 385; chucks and chucking. 385; types of chucks, 385: cutting operations, 388; cutting tools, 388; tool nm$rs. 389: grinding lathe tools, 390; feeds, speeds, and depth of cuts, 390; taper x”d taper iwning, 392; screw threads, 396; thread measuremer~ts, 396; other threads, 401; turret l&es and screw machines, 402; proper selection and “se of tools, 404

~eToo~Co~~o~ . . . . . . . . . . . . . . . . . _ . 405 Electrical components and controls, 405; power supply, 405; transformers, 405; motors, 406; solenoids, 407; rekqs, 407; switches, 407; control circuits, 408; hydraulic com- ponents, 409; tape 01 rmrnerical co”trol, 411

Grinding and Grin achines. . . . . . . . . . . . . . . 413 Basic operations of grindiing, 413; grinding action, 413; grinding wheels, 414; pclishing abrasives. 419: grinding machines, 419; universal

tf .. inding machine, 419; plain grind-

ing machi”ez 420; s&ace grinding machine, 422; D er gnndmg processes, 423

Tool and Die g . . . . . . . . . . . . . . . . . . . 425 C)oalifications of a toolmaker, 425; education, 425; skill, 425; knowledge, 425; tool- maker’s kit, 425; lawut and machining, 426; jigs and fixhxe~, 426; small cutting tools, 426; gage making, 426; die making, 426

Gears and Gear Cu . v . . . . . . . . . . s . . . . a 428 Kinds nf gears, 428; gear t&b, 428; terminology of gear tooth, 429; speeds and feeds, 431; gea: making processes, 431; the milling process, 432; types and cutting of gears, 43%; spur gears. 432; bevel gears, 433; spiral bevel gears, 435; hypoid gears, 435; helical gears, 43.5; the hobbing process, 435; the shaping process, 436; shaving of gear teeth, 436

coolants. . . . . . . . . . . . . . . . . . 437 Lubrication, 43’7; viscosity. 437; coolants and cutting fluids, 438

* . . rn . m . . . . . . . . . . . . . . . . . 440 Irfiscellanet;us metric amversion factors, 440; measures of pressure and weight, 440; miswz~laneonr measures, 440; temperature conversions, 441; interconversion table for units of voEume arnd weights, 442; interconversion table for units of energy, 443; mensura- tion--length, 4444; mensuration-area, 444; mensuration-solid contents; 444; men- suraticn-miscellaneous, 444; conversion of millimeters into inches, 445; conversion


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of inches into millimeters. 447; decimal equivalents of millimeters and fractions of millimeters. 44s: &xkn:d eouivaient carts of one inch. 449; diaeonals of hexaeons


and squarer. 449: .~meriran ‘standard &read dimensions’and tap d&l sizes-fra&nal .:Ts, 450: standards for \vi:*: gauges. 451; United States standard gauge sizes, 452; I .Irdness conversion. 4.53; Morse tapers. 454; conversion uf minutes of arc into decimal> <,f a degl-rr. 455: circumferences an ‘d areas of circles, 456. cutting speeds for tnming- dl-illing-tapping with high speed steel cutting tools, 457; multiple threads, 458; table of tangrxts. 459: surface cutting speeds, 461; decimal equivalents. 462: suggested feed per tooth for sin&w d carbide tipped cutters, 463; machinalAl::, ratings and cutting speeds for steel. 463: range of values of II obtained in variou; &lling operations with high speed str-1 and sintered carble cutters, 464; suggested feed per tooth for high speed steel milling cutters; 464; table of square, cube, and _(~ lxih powers of the di- ameters for round wires. 46.5: relationship behveen the Brir.zll hardness of the pa,: to be milled and the cutting speed of the milling cutter fn.- ditierent catting tool and work nxztrrials. 468; cutting speeds in feet per minute. 46s cutting speeds in fret per minute-high &lit!- and hey>- duty, 470

Index . . . . . . . . . . . . . . . . . . . . . . . . . 472

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The purpose of this book is to assist the worker in becoming familiar with the fundamentals of metal- working; to provide reference material that may be of the broadest use. both to beginner and apprentice :alike; as an expert in the machine or school shop; or iis it Irotne tnechanic.

Craftsmanship in metalworking is a combination of knowledge of how to xse tools and skill with the hands. Uniortunately, there is no magic shortcut to craftsmanship. No book could possibly give you all the tricks of the trade or the skill of the old master craftsman. These must be learned from practice at the bench and at the machine, through the sense of touch, familiarity with the tools themselves, and through endless trials alid errors that teach the better ways of doing every single thing. On the other hand, books can supply the all-important source of knowl- edge for the mastery of basic principles-and later for broadening skills. the techniques and procedures upon which master craftsmanship is built.

The Metalworking Handbook Principles and Procedures explains the specific purposes, correct use, and proper care of metalworking hand- and power-driven tools for cutting, shaping. and drilling metals.

Several chapters deal with metals and plastics;

measuring tools; metalworking hand tools; sheet metalworking machines, working with met+ solder- ing; riveting; sheet metal fasteners; metal spinning; metalworking power tools; layout and benchwork, machine tool controls; tools and die making; and lubrication and coolants. Other chapters cover the fundamental principles and operations of various types of metalworking machines.

The numerous illustrations and diagrams through- out this book should prove unusually helpful in com- prehending the text. The many tables throughout the book should be of value even after the text becomes familiar.

The workers in metals and materials worthy of the most exacting skill may well enjoy a constant and enduring pride and satisfaction in their life’s work. Their work is an occupation that has steadily and rapidly increased in value to industry, to the com- munity, and to the nation today, and is sure to play an even more important role iq the future.

The .Metalworking Handbook Principles and Procedures has been produced with the con- viction that it will be a welcome and valued aid to the many thousands who have desired a book of this type on the subject.

J. T. A.

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TO choose the metals a:ld plastics best suited for fabrication or repair. you must have a knowledge of

the plxsical and mechanical properties of materials and I&V the methods of identifving materials that ;xre not clenrlv marked. For inst&ce, stainless steel ;and ~:aplx~r-nickel are quite similar in appearance, I)II~ wmplctrly different in thei,r mechanical proL>- ertics. and cannot be used interchangeably. A ther- mosetting plastic may look like a thermoplastic, but the former is heat resistant, whereas the latter is biglily flammable.

Properties of Maiericds

The physical properties of a metal or a plastic de- terinine its behavior under stress, heat, and exposure to chemicallv active substances. In practical appli- cation, beha;ior of a material unier these conditions determines its mechaoical properties, indentation, and rusting. The mechanical properties of a material. therefore, are important considerations in selecting material for a specific job. The following information concerns metals. Plastics are discussed later in this chapter.

Stress is the amount of internal force with which a material resists a change in shape. Strain is the de- formation or change in shape that is caused by an applied load.

Strength is the property of a material which en- ables it to resist strain when stress is applied. The maximum stress applied to rupture the material is called ultimate strength. Under tension stress (pull- ing apart) it is called tensile strength; under com- pression stress, it is called compressive strength. Tensile strength (Fig. I), which is the commonly used strength term for metal, is measured in pounds of tension force necessary to cause failure of a one- syuare-inch cross section of the material. In engi-


Ixering construction, each part is designed so that the working stress of the material is much less than the breaking stress. The ratio of ultimate strength of a part to its working stress is called the factor of safety. A factor of safety less than 4 to 1 is oncorr- man; in many cases it may be as great as 15 or 20 to 1.

Figure 1. Tensile strength.

Plasticity is the ability of a material to withstand extensive permanent deformation without breaking or rupturing. Note the use of the word permanent here. The term plastic deformation is used to indi- cate a permanent change of shape. Modeling clay is an example of a highly plastic material, since it can be deformed extensively and permacently without rupturing.

Ductility (Fig. 2) is the ability of a material to permanently deform without rupture under tensile loads. Malleability (Fig. 3) is the ability of a mate- rial to permanently deform without rupture under compression loads.

Figure 2. Ductility.


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Figure 3. hlalleability.

The properti,es known as ductility and malleability RX special czes of plasticity. DuctiEily is the prop- erty that makes it possible for a material to be drawn out into 2 thin wire: in other words, it is the prop- erth- that enables the material to withstand extensive permanent deformation from tension. Al&ability is the property that makes it possible for a material to /IL- stamped, hammered, or rolled into thin sheets. In other words, a malleable material is one that can withstand extensive permanent deformation from compression.

?.fost metals that exhibit one of these properties also exhibit the other. However, this is not always true. For example, lead is very malleable (it can be permanently deformed in compression without break- ing) ~ but it is not ductile (it cannot be permanently deformed in tension to any great extent).

Brittleness (Fig. 4) is the tendency of a material to break suddenly with little or no prior deformation. Hard materials often are brittle, although a metal may be hard and still not be brittle. An example of a brittle material is hard cast iron. On the other hand, tungsten tool steel is hard but 1 nc

Figure 4. Britthness.

Toughness is the quality that enables a material to withstand shock, to endure stresses, and to be de-

It brittle.

formed without breaking. A tough material is not easily separated or cut and can be bent first in one direction and then in the opposite direction without fracturing.

Hardness (Fig. 5) of metal is generally defined as its ability to resist indentation, abrasion or wear, and cutting. Hardness of metals is usually associated with strength.

Figure 5. Hardness.

Fatigue is the action which takes place in a metal after a repetition of stress. When a sample is broken in a tensile machine, a definite load is required to cause that fracture. However, the same material will fail under a much smaller load if that load is applied and removed many times. In this way, a shaft may break after months of use even though the weight of the load has not been changed. The pieces of such a part will not show any sign of deformation. The mating areas of the section that fractured last will usually be quite coarse-grained, while the mating areas of other sections of the break will show signs of having rubbed together for quite some time.

Corrosion resistance is the ability of a material to withstand surface attack by the atmosphere, fluids, moisture, and acids. Some metals are highly resistant to practically all types of corrosive agents, others to some types of corrosive agents, and still others to only very few types of corrosive substances. Some metals, however, can be made less susceptible to corrosive agents by ccating or by alioying with other metals that are corrosion resistant.

Heat resistance is the property of metal which re- tains strength or hardness at high temperatures. This is particularly true of some types of alloy steels. A metal that retains its strength or hardness at elevated temperatures is called heat resistant. Tungsten steel (which, even when red-hot, can be used to cut other

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metals) and chromium molybdenum steel (which is used for piping and valves in high temperature, high pressure steam systems) are examples of heat- resistant metals.

Although weldability and machinability are not strictly properties, in the sense of the other p’op- erties discussed, they are important practical con- siderations in the fabrication or repair of any metal part. Weldability refers to the relative ease with which a metal may be welded. Machinability is the term used to describe the ease with which n metal ma;. be turned, planed, milled, or otherwise,shaped in the shop. Some metals are not easily machined because the\, are too hard. Some soft metals are not easily ma&ined because they are too tough. Both wldnhiiit! and machinability are really based upon the cond~ituztion of other properties of the material. rnther than being properties in themselves.

There are no hard and fast ru!es that can be used ill determining the machining characteristics of a nreial. Nany factors, such as the composition of the metal, the manufacturing process, and heat treat- ment, can have considerable effect on the machin- abilit! of a metal. For exampEe, an increase of one of the elements in the composition can increase or de- crease machining characteristics; differences in tem- peratures and rates of cooling used in heat treatment can change the metal from hard to soft, or vice versa. Hot or cold working or casting in the manufacturing process can change the machinabilit!- characteristics by changing the internal structure of the metal.



.l’eials are divided into two general types-ferrous and nonferrous. Ferrous metals are those whose ma- jor element is iron. Iron is the basis for all steels. Nonferrous metals are those whose major element is not iron, but they may contain a small amount of iron as an impurity.

Ferrous Metals

Zron ore; the basis of all ferrolls metals, is con- verted to metal (pig iron) in a b&t furnace. alloy- ing elements can later be added to the pig iron tu obtain a wide variety of metals with different char- acteristics. The characteristics of metal can he further changed and imp:oved by heat treatment and by hot or cold working.


Figure 6. Blast furnace. Krons

The product of the blast furnace (Fig. 6) is called pig iron. In earlv smelting practice, the arrangement of the sand molds into which the molten crude iron was drawn resembled groups of nursing pigs. hence the name.

Pig iron, which is composed of approximately 93 per cent iron, 3 to 5 per cent carbon. and varying amounts of impurities, is seldom used directly as an industrial manufacturing material. It is used as the basic ingredient in making cast iron, wrought iron, and steel.

CAST IRON. Cast iron is produced by resmelting a charge of pig iron and scrap iron in a furnace and removing some of the impurities from the molten metal by using various fluxing agents. There are many grades of cast iron as to strength and hardness. The quality depends upon the extent of refining, the amount of scrap iron used, and the method of cast- ing and cooling the molten metal when it is drawn from the furnace. The higher the proportion of scrap iron, the lower the grade of cast iron. Cast iron has some degree of corrosion resistance acd great com- pressive strength, but at best the metal is brittle and has a corr;paratively low tensile strength, and ac- cordingly has very limited use in marine service.

WROUC~IT IRON. Wrought iron is a highly refined pure iron which has uniformly distributed particle: of slag in its composition. Wrought iron is consid- erably softer than cast iron and has a fibrous internal structure, created by the rolling and squeezing given to it when it is being made. Like cast iron, wrought iron is fairly resistant to corrosion and fatigue. Be-

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caose of these characteristics. wrought iron is used extensively for low pressure pipe, rivets. and onils.

Plain steels

pig iron is converted into steel by n process which separates and ren,oves impurities from the moltm iron b\, use of various catalytic agents nnd extremely high t&nperatures. During the refining process, prac- tic& all of the carbon originally present in the pig iron ;s burned out. In the 6nal stages, where high carbon alloys are desired, measured amounts of car- bon arc added to the relativeI!- pure liquid iron to produc.: carbon steel of n desired grade. The amount of carbon added controls the mechanical properties of the finished steel to R large extent. as will be 1wintrxi out in the following paragraphs. After the steel has been drawn from the furnace sod allowed to solidifv. it mnv be sent either to the stockpile, or to shapi~~g mills for rolling and forming into plates, hill:+. Ixus, or structur;il shapes.

.!‘!ui;z stcds that have smdi additions of sulfur 11 ;arrt\ sometimes phosphorus) are called free cutting ~sfwls. These steels have good machining character- istics and are used in applications similar to carbon steels. .&ddition of sulfur are phosphorus results in limiting its ability to be formed hot.

Low CARBOX STEEL. Low carbon steel (0.05 to 0.0:30 per cent), usually referred to as mild steel, can be easily cut and bent and does not have great ten- sile strength, as compared with other steels.

MEDIVJI CARBON STEEL. Medium carbon steel (0.30 to 0.60 per cel& carbon) is considerably stronger thw mild carbon steel. Heat treated machinery parts nre made of this steel.

Hrw C~nnos STEEL. High carbon steel (0.60 to 1.25 per cent) is used for many machine parts, hand tools, and cutting tools, and is usually referred to as cnrbon tool steel. Cutting tools of high carbon steel should not be used where the cutting temperature would exceed 400 degrees.

Alloy Steels

The stee!s previouslv discussed are true alloys of iron and carbon. When other elements are added to iron during the refining process, the resulting metal is culled alloy steel. There i,re many types, classes, and grades of alloy steel. A few of the more common alloy steels and the effects of certain alloying ele- ments upon the mechanical properties of stcc! are discussed briefly below.

Corrosion resistant stwl (conm~only called stnin- less steel) is an alloy which contains relntively large amounts of chromium and nickel. Corrosioo resistant strd wsi ts corrosion, attack by acid. and scaling. It is classified hy the Socirty of Automotive Enginrers as either a chromium allov ot’ a chromiun~ nickel alloy.

NICKEL STEEL.. Nickel steel. which rtsually contains 3 to 5 per cent nickel, has superior strength and toughness and is often used for armor plate.

V~~mrunt STEEL. \‘anadinm steel (usuallv con- taining from 0.15 to 0.25 per cent wnndium) is used for crankshafts. axles. ge:\rs. and other machine parts where high strength aocl fntiRut% wsistnnw is tle- sired.

CAIIBON-~~OI.~.UI)EN~I~~ STEEL. Molybdenum, in combination with chromium and nickel, is added to steel to produce a tough carbon-mol~bdenmn steel (Chlo) suitable for steam fittings, valve bodies, and boiler plates. It is also used in place of the more ex- pensive tungsten for the cheaper grades of high speed steel cutting tools.

Hxw SPEED STEEI. (HS ). High speed steel has the qualit\ of red-hardness. Cutting too!s made from the variotis types of HS steei cm be used up to, nod after, the time the point has become a dull red, or to n temperature of approximately 1100 degrees. There are several different types of HS steels, some of which are listed in this chapter.

TPSC,STEN BASE STEELS. Tun@en base steels are one of the most common types used. Though the percentages may vary with different grades, one common type is the Tl. It is composed of 18 per cent tungsten. 4 per cent chromium. and 1 per cent vanadium

I\.~OLYBDENUIM Bose STEELS. hfolybdemun base steels are similar to tungsten base steels, except that some of the tungsten is replaced with molybdenum. One of the common types is the M2; it is composed of 5 per cent molybdenum, 6 per cent tungsten. 4 per cent chromium, and 2 per cent vanadium.

Nonferrous Metals

Copper, nickel, lead, zinc, tin. and aluminum are included among the nonferrous metals. These metals, and the many combinations in the form of alloys such as brass, bronze, copper-nickel, and so on, are used in large amounts in constwction and mainte 11i,,,ce.

COPPF.R. Copper is a metal which lends itself to :L vsiety of GSCS. It comes in the form of wire, rod,

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bar% sheet plate, and pipe. Copper is used also in copper alloys such as brass and bronze. As a con- ductor of both heat and electricity, it ra:lks next to silver. It also offers a high resistance to salt water corrosion. The green tarnish which sometimes forms on its surface has a detrimental effect upon the metal and is easily cleaned off.

Copper becomes hard when worked, but can be softened easily by heating to a cherry led and then cooling. Its strength increases rapid]!- with temper- atures above 400°F.

Pure copper is normaliv wed in molded or shaped forms where machining is oat required. Copper for normal use generally is a!loyed with an element which provides good machinability characteristics.

S~XEL. Nickel is a hard, maIleablel and ductile mttnl. It is resistant to corrosion and tl;erefore is II&;: used as a coating on other metals. Combined v1t11 ~I~IwI. metals in an alloy. it makes a tough strong .111<)\..

LAW Lend weighs about 700 pounds per cubic foot. It is available in pig and sheet form. Sheet lead is used to line sinks or protect bench tops where a ,great deal of acid is used. The surface of lead is grayish in color, but when it is scratched or scraped, it &comes very white. Because of its softness, a lead block is often used as a backing material when punching holes with a hollow punch, or for bump-

7 or hammering sheet metal forms. When lead is .j :“yed with tin in various proportions to form soft solders, you have one of the most commonly used alloys of nonferrws metals.

Zrsc. Zinc is a comparativ+ soft, vet somewhat brittle metal. Its tensile strength is siighth greater than that of aiuminun. In the manufacture’ of brass, zinc is used :LS an allwing metal. copper being the base metal. Because if its resistance to corrosion, zinc is used as a protective coating for less corrosion resistant metals, principa!Iv iron and steel. There are three methods of applyin$ a 2’~ coating: (1) Elec- trop:ating in a zinc-ac.d solution; (2) hot dipping, where the metal is dipped into a bath of molten zinc; (3) c,herardizing; where zinc is reduced to a gaseous state and deposited on the base metal.

Trx Tin is seldom used except as a” alloying in- gredient. Alloyed with iead it makes a soft solder. and alloyed with copper, it produces bronze. Lead and tin both res!:qt corrosion verv well, but tin has the added advantage of being n&poisonous. zany food containers are fabricated from sheet mate&l which has been coated with tin.

.~L~:XGSLX<. Aluminum is being used more and

more in construction because of i:, .:ht weight, easy workability, good appearance, and other desir- able properties. Pure aluminon~ is soft and not ver\ strong. When alloying elements such as magnesium. copper, nickel. and silicon are added, a much stronger me +:,I is produced. Aluminum alloys cao be strain har,.ic,I-d, solution heat treated, and age hardened, ei; .er artificially or naturally.

TRUE Buss. True brass is a” alloy of copper and zinc. Complex brasses are those containing additional agents, such as aluminum, lead, iron, manganese, or phosphorus.

Brass is classified as leaded and unleaded, meaning that small amounts of lead may or may not be used in the copper-zinc mixture. The addition of lead im- proves the machinability of brass.

BROXZE. Bronze made of 84 per cent copper and 16 per cent tin was the best metal available before steel making techniques were developed. Although bronze was originally an alloy of copper and h. many complex bronze alloys containing three or more elements have been developed. There is no dis- tinct line between brass and bronze. In fact, com- mercial bronze (used for hinges and other hard- ware) is really a low brass containing 90 to 95 per cent copper and 5 to 10 per cent zinc.

COPPER-NICKEL ALLOY. Copper-nickel alloy has come into its own in recent years, because of its high resistance to the corrosive effect of salt water. It is used in piping and tubing. In sheet form, you may use it to construct small storage tanks and hot-water reservoirs. Copper-nickel alloy may contain either ?‘ per CW’ >per td 30 per cerrt nickel or 90 per cent copper and 10 per cent nickel. This alloy must be worked cold, although it has the general working characteristics of copper. Copper-nickel is best joined by the silver soldering process.

NICKEL-COPPER ALLOYS. Nickel-copper alloys are stronger and harder than either nicket or cbpper. They hav? a high resistance to corrosion and are strong enough to be substituted for steel where COT- rosion resistance is of primary ,importance. Probably the best known nickel-copper allov is “Monel” metal. Monel contains 64 to 68 per cent iickel, about 30 per cent copper, and small percentages of iron, man- ganese, silicon, and cobalt. It is actually a natural alloy, because the combination of nickel and copper exists in the ore when mined and is retained in the refining process.

K-MONEL. “K-Monel” is essentially the same as “Monel,” except that it contains about 3 per cent aluminum, and is harder and stronger than other

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-grades of hlonel. K-Monel stock is wry difficult to machine, but its machinabilih- ran be improved con- siderably by annealing the metal immediatelv bef”re machining.

Designations and Markings

Knowledge of the standard designations of metals and the systems of marking metals is necessary so that you can select the proper material for a specific job. The standard designations discussed in this chapter are index numbers that are used to indicate the composition of the various metals. The two ma- jor setems used for iron and steel are those of the So&t\- of Automotive Engineers (Sr\E) and the irn&a:~ ircn and Steel Institute ( NISI). The Alw mi:~aw :&soriution method is csed for aluminrnn ~tlwr ~~rnfwrws metals we designated by the per- WI~~:I;:I .III~ t!~ws of ciemcnts in their composition.

b’~wii~r~~s METAL Des~cr.~noss. You should be fa- iii!li:~i \vith tl le s\ 5 ..-t em of steel classification used b\ .%‘!: x111 .?.ISI. These svstems are in c”mmon use and lltilizc a four- or five:digit number to indicate the composition of the steel. The one mnj”r difference lwtxx,ern the two svstems is that the .%ISI xstem laes R kttrr before thh number to show the 1,;“~s used in the making “f the steel. The letters used are as fo!l”ws: B-.Gd Bessemer carbon steel: C-Basic open-hearth or basic electric furnace carbon steel; and E-Electric furnace alloy steel.

EWll& SAE IQ 20

.AISI c IQ 20 -


Basic Opu- Plain Carbon Carbon Hearth Carbon Steel Content


The first digit indicates the type of steel: 1 stands fol- carbon steel; 2 is nickel steel; 3 is nickel- chromium steel: 4 is molvbdenurn steel; .5 is chro- mium steel: 6 is chromium-vanadium steel; 8 is “Na- tioual Emergency” steel; and 9 is silicon-manganese steel. (The group identified as “National Emergency” steel, wmber 8 in the SAE/nISI svstems, includes various IOU’ dlOV nickel-chromi~~m-m”lvl~d~~~~~~m steels developed &ring \Vorld \Var Il. Irluch of the al:“\, content of these steels can be derived from scrap alloy, thus conserring the sup& of al!oy rna-

terials. These steels are retained in most steel classi- fications today.)

The second digit in the S.4EIAISI number indi- cates the series within the group indicated b!, the first digit. The term series ill this c”nnt!ction r:sunll\ refers t” the percentage “f the chief nlloyiq: ele- ment. Sometimes the second digit gives the nctual percentage of the chief alloying element. In other cases, however, the second digit rnny be used to indicate the relative position of the series in the group, without reference to the actual percentage. The last two or three digits indicate the average car- bon content of the steel. In order to make the various steels fit into this classification it is sometimes nec- essarv to vary the system slightly. These variations are easily understood if you understand the system. (See the following examples.)

(1) SAE 1035. The first digit is 1, so this is a carbon steel. The second digit, 0, indicates that there is no other important nll”ying elemrnt, thrrefore, this is a plain carbon steel. The next two digits, 35, indicate that the aoerage percentage “f carbon irl steels “f this series is 0.35 per cent. The actual car- bon percentage in this series ranges from 0.32 t” 0.38.

(2) SAE 1146. This is a carbon steel (first digit) with an average manganese content of 1.00 per cent (second digit) and an average wrbon content of 0.46 per cent. The 1100 series of steels are known as free cutting steels.

(3) SAE 4Oi7. The first digit, 4, indicates that this is a molybdenum steel. The secclnd digit, 0, indicates that there is no other equally important alloying cle- ment; therefore, this is a plain m~~lybdenwn steel. The last two digits. 17, indicate that the nverage car- bon content is 0.17 per cent.

Other series within the molvbdenom steel group are indicated by the second digit. If the second digit is 1, the steel is chromium-molybdenum steel. If the second digit is 3, the steel is a nickel-chromium- molybdenum steel. If the second digit is 6, the steel is a nickel-molybdenum steel. In such cases, the sec- ond digit does not indicate the actual percentage of the alloying elements other than molybdenum

(4) SAE 51100. This number indicates a chro- mium steel (first digit) with nppr~~simatel~ 1.0 per cent chwmium (seumd digit) and an nverage car- bon content of 1.00 per cent (hut thrrc: digits). The actual chromium content of S.4IC 51 100 strcls ma\ wry from 0.5 to 1.10.

(5) SAE 52100. This number indicates a chromium steel (first digit) of a higher alloy series (second

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digit) than the SAE 51100 steel previously described. Yote that in this case the second digit. -7. mereI!- identifies the series but does not indicate the per- centage of chromium. A 52100 steel would actualh have from 1.30 to I.60 per cent chromium with a;1 nwiage carbon content of I.00 per cent ( last three digits).

There used to be a 7000 series S.4.E steel, but under a new system it is no longer used. The current commonly used tool steels have been classified bv the Am&can Iron and Steel Institute inio seven ma- jor groups and each commonly accepted group or subgroup has been assigned an alphabetical letter. Xfethodr of quenching. applications. special char- actwizties. and steels for particular industries were r~ii2rii~~~rrd in the folIo\ving t\-pe classification of tool

c :I ‘:“,’

‘.!‘.:tt:,r h:wderlirro

*hick resistinn ?

Cdd \rork

Symbol and t\pe



O-Oil hardening .‘t-Medium dIO> D-High carbon-high


Hot work a-( K 1 to N 19 ix!. chmmium base, H 20 to Ii 39 incl. tungsten base, 840 to K.59 incl. molyb- denum base )

High speed T-Tnngsten base XI-MoIvbdenum base

Special purpose

.\fold steels P

NoxFERKJcs MET.% DEsrcxATIoss. Xonferrous metals are generall\~ grouped according to the allov- ing elements. Examples of these groups are brass, bronze, copper-nickel, and nickel-coppi. Specific designations of an alloy are described by the amounts and chemical symbols of the alloying elements. For erample, a copper-nickel alloy might be described as capper-nickel, 70 Cu-30 Ni. The 70 Cu represents the percentage of copper and the 50 Si represents the percentage of nickel.

Common alloying elements and their chemical symbols are as follows.

Aluminum - - - Al Carbon---C Chromium -- - -- Cr Cobalt - - - Co copper - -~ - cu Iron---Fe Lead---Pb Manganese - - - Mn Molybdenum - - - MO Nickel - - - Ni Phosphorus - - - P Silicon - - - Si Sulphur - - - S Tin----So Titanium - - - Ti Tungsten - - - W vanadium - - - v Zinc---Zn

In addition to the type of designations previously described, a trade name (such as Mon.4 or Inconel) is sometimes used to designate certain alloys.

The Aluminum Association uses a four-digit des- ignation system similar to the SAE/AISI system de- scribed for steels. The numerals assigned with their meaning for the first digits of this system are as follows.

Aluminum (99.00 per cent minimum and greater) lxxx

Major Alloying Element Copper 2xxx Manganese 3xxx Silicon 4xxx Magnesium 5xx.x Magnesium and Silicon 6xxx ZhC 7xXx Other element Bxxx

The first digit indicates the major a!!oying element, and the second digit indicates alloy modifications or impurity limits. The last two digits identify the par- ticular alloy or indicate the aluminum purity.

In the lxxx group for 99.00 per cent minimum alo- minrlm, the last two digits indicate the minimum aluminum percentage to the right of the decimal point. The second digit indicates modifications in impuritv limits. If the second digit in the designation is zero, ;t indicates that there is no special control on

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individual impurities. If it is 1 through 9. it indicates some qwcial control of one or more individual im- purities. As an exanq~lr. 10:30 indicates il 99.30 1x1 cent minimrlm nlnminrm~ without sprrial control on individual impurities, and 1130. 1230. 1330, and so on indicate the came purity with special control of one or more individual impurities.

Deriqations having the numbers 2 through 8 are alumi”rml allovs. In the 2xsx through 8~x1 allo\. ~ro:qx. the se&d digit in the designation indic&s allo\- modification. The last two of the four digits in tkr designation have no special significance but serve w& to identifv the different alloys in the group.

111 .tddition to thr four digit allo!~ designation, a Iptter or letter/number is included as a temper des- icI~;ltirin The temper de.TiSnation follows the four riicii alIn\ ~~urn!~~r and is separated from it bv a d.lSll~ 1:or mln1p1c. 2024-T6 is an aluminum-copper :1110!,. sol&on heat treated, then artiEciall!- aged. T6 i\ ii]? tvmpel- designation. The aluminum allov tem- per desiq~:ations and their meanings are as follows.

F - As fabricated 0 - Annealed and recrvstallized

(wrought only j. H - Strain hardened ( wrought only )

HI, plus one or more digits, strain hardened or&

H2. plus one or more d&its, strain hardened then partial!\ annealed

H3, plus one or more digits. strair. hardened then stabilized

W - Solution be-t treated-unstable temper

T - Treated to produce stable tempers other than F. 0. or H

T2 Annealed (cast only) T:3 Solotion heat treated, then

cold wxked T4 Solution heat treed and

naturnllv .iSed to a substantialh stable condition

T.5 Artificially ased onl) 76 Solution heat treated, then

artificinlh~ aged T7 Solution &eat treated, then

stabilized T8 Solution heat treated. cold

lvorked, then nrtificiallv aged

T9 Solution heat treated, artificiall! aged, then cold worked

T10 Artificially nged, then cold worked

Note that while some temper designations appl) only to wrought products and others only to cast products, most apply to both. A second digit may appear to the right of tht nvxl~anical treutment, in- dicating the degree of hardening: 2 is l/4 hard, 4 is 112 hard, 6 is 3/4 hard, and 8 is full hard. For example, the alloy 5456.II32 is an aluminum/ magnesium alloy, strain hardened. then stabilized, and is l/4 hard.

STAND.~~ MARKING OF METALS. The metal mark- ings described in this section include the color svm- bols used for nonferrous metals.

Continuous Identification Marking

The purpose of the cnntinuous identificntion mark- ing system is to provide a means fw pasitive identi- fication of metal products even after some portions have been used. In the continuous identification marking system, the markings appear at intervals of not nxxe than three feet. Therefore, if you cut off a piece of bar stock, the remaining portion will still carry the proper identification. Some metals such as small tubing. coils of wire, and small bar stock can- not be marked readily ba this method. On these items, tags with the q&d marking information are fastened to the metal.

The continuous identification marking is actualI! printed on the metals with a heavy ink that is almost like a paint.

The manafacturer is required to make these mark- ings on materials before delivery. Figure 7 shows the normal spacing and layout.

For metal products, the continuous identification marking must include (1) the producer’s name or registered trademark, and (2) the commercial des- ignation of the material. The producer’s name or trademark shown is that of the producer who per- forms the final processing or finishing operation before the material is marketed. The commercial designation ineludes (1) a material designation such as a11 SAE number, an AI.9 number, or nn ASTM (American Society of Testing Materials) specifica- tion and (2 j n physical condition nnd quality des- ignation. that is, the designation of temper or other physical condition appro‘:ed by a nationally rec- ognized technical societv or industrial nssociation such as the .4mericnn Iron and Steel Institute. Some

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Figure 7. Continuorts identification marking

of the phvsical condition and quality designations for various metal products are as follows.

CR - cold rolled CD - cold drawn HR - hot roiled AQ - aircraft quality CQ - commercial quality 1/4H - quarter hard l/213 - half hard H -hard HTQ - high tensile qualit!- AR - a~ rolled HT - heat trrated C - ground

Color Marking

For some yzars, a sptem of color synboIs with a

related color code has been used for the idcntifi- cation of nonferrous metals. Although the color marking system is being replaced by continuous identification marking, you should still be familiar with the nonferrous color svstem. Some of the non- f~rous stock that you obtain is likeIv to be marked with color symbols, since the material marked and coded under the color system may not be entire& used up for several years.

COLOR SYMBOLS. The term color symDo2 refers to the color marking nctuall\. painted on the nonferrous metal. A symbol is n design composed of one, two. or three colors aud painted on a conspicuous area of the picw. When the .symbol frmsists of more than om color. the colored imx are :idjxmt to cwh other.

There are two types of color synbols. Spot sy,n- bols that arc applied to r:ach end of solid stock that is at least R/4 inch in diameter (for round stock) or

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The pupme of applying thr color symbol at CYWII end oi the piece is to ensure thr pxwoce of onr svmbol even after pari of tllc piect 11~s bwn cut off 311d 1lSC~d I% not forget this ,“‘“,“‘““. If for smnc I-ea,- 5011 tllc i(lelitifviilfi s!.inbi)l is rrlt r~lf fr(~nl boih wds. Ix? slir(! to renew the color symbol while+ you still knmv what the material is. Othrnvise someone \vill be left with the problem of identif\~ing an unmnrked piece of metal.

Ccxo~ CODE. The color code used for the identi- fication of nonferrous metals is v&ted to, but is nof the same as; the color svnrbols just described. The color s!,mbols are actual &ors painted on the metal. The color code is a method describing these symbo!s in numbers. To have a numerirnl color code, each coIor must be given a nxnber. There are 13 colors used in the color svnbols, so thr numbers used in the color code ale 1 through I:? l-he colors :,TP RF raii,yd alph;lhrticall\~ md t!ien nssigid a nu~nlxy The color nombers ire as follows.

Color Black Hue Bronze B~O\Vll

Dark Blue Green Lead Ormg Pllrpie Xed l-m White Yelhi~

Number Code I 2 3 4 5 6 7 8 9

10 11 12 13

Thr color with the lowrst number ill ;uw co101 svmbo! (that is, the color name that OCCIIIS first in this nlphabetical arrangement) is al\w\-s r&wed to RS the prinmrt/ color. In n color code number. the first digit identi& the primary color. The other major color, therefore. becomes thr .seconriorr~ colol- 2nd is

expressed after the primari- co!or. rVlwn i, stl-ipc is used, its color number is nitvnvs expressed last.

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would then call this a !~ello~-~ellot~.-green symbol in critical situations where a specific metal is desired.

with a color code of 13-13-6. Some of the methods that will be discussed in this section are magnet tests, chip tests, file tests, acid

Identification of Metals reaction tests, and spark tests. In Table 1 you will find information related to surface appearance mag-

the \m+ous base metals. such as iron. copper, lead. netic reaction, lathe chip test, and file test. The acid zinc, and ahm~inum have certain identifying char- test and the spark test are discussed in more detail acteristics-surface appearance and weigh-by which later in this chapter. When performing these tests it persons who work with or handle these materials is advisable to have a known sample of the desired readi]!- distinguish them from one another. There are material and make a comparison. When using these a number of related alloys which resemble eac’l tests you will need good lighting, a strong permanent other and tb& base metal so ciosel\- that they def\ magnet, and access to a lathe. A word of caution accurate identification by simple means. when performing these tests: Do not be satisfied

There are other means of identification of metals. with the results of only one test. Use as many tests It should be noted that these methods by no means as possible so that you can increase the chances of pro~-id~ positive identification and should not be used making an accurate identi6cation.



Red to brown

Copper-nickel smooth: gray to yellow or yellowish



Dark gray: smooth; sometimes green

Cut by knife, any

Cuts easily. smooth continuous chip

Plain carbon steel

f 1. Swdess steels that have less than 26 percent alloying elementS react to magnet.


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Spark Test

Spark testing is the identification of a metal by ob- serving the color, size, and the shape of the spark stream given off when the metal is held against a grinding wheel. This method of identification is ade- quate for most shop purposes. Where the exact com- position of a metal must be known, a chemical analysis must be made. Identification of metals by the spark test method requires considerable expe- rience. To gain this experience, you will need to practice b;; comparing the spark stream of unknown specimens with that of sample specimens of known composition. It is the practice in many shops to maintain specimens of known composition for com- parison with unknown samples.

Proper lighting conditions are essential for good slwk testing practice. The test should be performed iu an iarea where there is enough light, but harsh or glaring light should be avoided. In many shops you may find that a spark test cabinet has been erected. Generally, these cabinets consist of a box mounted on the top of a workbench and have a dark painted interior. Inside the cabinet a bench grinder is mounted. Test specimens of known composition are contained in she!ves at the end of the cabinet. Where possible, the testing area should be in such a location that heavy drafts of air are eliminated. Air drafts can change the tail of the spark stream and may re- sult in improper identification of the sample.

Speed and pressure are factors that need to be considered when making the spark test. The faster the speed of the wheel, the larger and longer the spark stream will be. Generally speaking, a suitable grinding wheel for spark testing is an &inch wheel turning S600 revolutions per minte (r.p.m.). This provides a surface speed at 7537 feet per minute. The pressure of the piece against the wheel has sim- ilar effects. The more pressure applied to the test piece, the larger and longer the spark stream. The test piece should be held lightly but firmly against the wheel with just enough pressure applied to prevent the piece from bouncing. Remember that the same amount of pressure must be applied to the test speci- men as is applied to the sample being tested,

The grain size of the grinding wheel should be from 30 to 60 grain. It is very important to remember that the wheel must be clebn at all times. A wheel loaded with particles of metal will give off a spark stream of the type of metal in the wheel, mixed with the spark stream of the metal being tested. This will result in serious confusion as to the true nature of

the metal. The wheel must be dressed before spark testing and before each new test of a different metal.

The spark test is made by holding a sample of the material against a grinding wheel. The sparks given off, or the lack of sparks, assist in identifying the metal. The length of the spark stream, its color, and the type of sparks are the features for which you should look. The definitions of the various terms used in spark testing are shown in Fig. 9.

* .


figure 9. Meaning of the terms used in spark testing.

The greater the amount of carbon present in a steel, the greater the intensity of bursting that will take place in the spark stream. To understand the cause of the bursts, remember that while the spark is glowing and in contact with the oxygen of the air, the carbon present in the particle is burned to carbon dioxide (CO,). As the solid carbon combines with oxygen to form CO? in the gaseous state, the increase in volume builds up a pressure that is relieved by an explosion of the particle. An examination of the small steel particies under a microscope when they are cold reveals a hollow sphere with one end completely blown away.

Steels having the same carbon content but differ- ing alloying elements are not always easily iden- tified because alloying elements affect the carrier lines, the bursts, or the forms of characteristic bursts in the spark picture. The effect of the alloying ele- ment may retard or accelerate the carbon spark, or make the carrier line lighter or darker in color. Molyb- denum, for example, appears as a detached, orange- colored spearhead on the end of the carrier line. Nickel seems to suppress the effect of the carbon burst. But the nickel spark can be identified by tiny

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Spark Test

Spark testing is the identification of a metal by ob- serving the color, size, and the shape of the spark

stream given off when the metal is held against a grinding wheel. This method of identification is ade- quate for most shop purposes. Where the exact com- position of a metal must be known, a chemical analysis must be made. Identification of metals by the spark test method requires considerable expe- rience. To gain this experience, you will need to practice b;; comparing the spark stream of unknown specimens with that of sample specimens of known composition. It is the practice in many shops to maintain specimens of known composition for com- parison with unknown samples.

Proper lighting conditions are essential for good slwk testing practice. The test should be performed iu an iarea where there is enough light, but harsh or glaring light should be avoided. In many shops you may find that a spark test cabinet has been erected. Generally, these cabinets consist of a box mounted on the top of a workbench and have a dark painted interior. Inside the cabinet a bench grinder is mounted. Test specimens of known composition are contained in she!ves at the end of the cabinet. Where possible, the testing area should be in such a location that heavy drafts of air are eliminated. Air drafts can change the tail of the spark stream and may re- sult in improper identification of the sample.

Speed and pressure are factors that need to be considered when making the spark test. The faster the speed of the wheel, the larger and longer the spark stream will be. Generally speaking, a suitable grinding wheel for spark testing is an &inch wheel turning 330 revolutions per minte (r.p.m.). This provides a surface speed at 7537 feet per minute. The pressure of the piece against the wheel has sim- ilar effects. The more pressure applied to the test piece, the larger and longer the spark stream. The test piece should be held lightly but firmly against the wheel with just enough pressure applied to prevent the piece from bouncing. Remember that the same amount of pressure must be applied to the test speci- men as is applied to the sample being tested,

The grain size of the grinding wheel should be from SO to 60 grain. It is very important to remember that the wheel must be clebn at all times. A wheel loaded with particles of metal will give off a spark stream of the type of metal in the wheel, mixed with the spark stream of the metal being tested. This will result in serious confusion as to the true nature of

the metal. The wheel must be dressed before spark testing and before each new test of a different metal.

The spark test is made by holding a sample of the material against a grinding wheel. The sparks given off, or the lack of sparks, assist in identifying the metal. The length of the spark stream, its color, and the type of sparks are the features for which you should look. The definitions of the various terms used in spark testing are shown in Fig. 9.

* .


figure 9. Meaning of the terms used in spark testing.

The greater the amount of carbon present in a steel, the greater the intensity of bursting that will take place in the spark stream. To understand the cause of the bursts, remember that while the spark is glowing and in contact with the oxygen of the air, the carbon present in the particle is burned to carbon dioxide (CO,). As the solid carbon combines with oxygen to form CO? in the gaseous state, the increase in volume builds up a pressure that is relieved by an explosion of the particle. An examination of the small steel particies under a microscope when they are cold reveals a hollow sphere with one end completely blown away.

Steels having the same carbon content but differ- ing alloying elements are not always easily iden- tified because alloying elements affect the carrier lines, the bursts, or the forms of characteristic bursts in the spark picture. The effect of the alloying ele- ment may retard or accelerate the carbon spark, or make the carrier line lighter or darker in color. Molyb- denum, for example, appears as a detached, orange- colored spearhead on the end of the carrier line. Nickel seems to suppress the effect of the carbon burst. But the nickel spark can be identified by tiny

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blocks of brilliant white light. Silicon suppresses the carboo burst even core than nickel. When silicon is present, the carrier line usually ends abruptly in a white flash of light.

To make the spark test. hold the piece of metal on the wheel in such a manner as to throw the spark stream about 12 inches at a right angle to your line of vision. You will need to spend a little time to dis- cover at just what pressure you must hold the sample to get a stream of this length without reducing the speed of the grinder. It is important that you do not press too hard because the pressure wili increase the temperature of the spark stream and the burst. It will also give the appearance of a higher carbon con- tent than tbat of the metal actually being tested. iftrr practicing to get the feel of correct pressure 911 the wheel until YOU are sure you have it, select a r.:xq~l~ of samples df metal with widely varying char- wlrristics, fw example, low-carbon steel and high- ~.dxm he!. Wold first one and then the other q,ainst the wheel, always being careful to strike the same portion of the wheel with each piece:With the eyes focused at a point about one-third of the dis- tance from the tail end of the stream of sparks, watching only those sparks which cross the line of vision, !;ou will find that after a little while you will form a mental image of the individual spark. After vou can fix the spark image in mind, you are ready to examine the whole spark picture.

Note that the spark stream is long (about 70 inches normally) and that the volume is moderately large in low-carbon steel, while in high-carbon steel the stream is shorter (about 55 inches) and large in volume. The few sparklers which may occur at any place in low-carbon steel are forked, while in high- carbon steel the sparklers are small and repeating and sonx d the shafts mav be forked. Roth will produce a white spark stream.

White cast iron (Fig. 10) produces a spark stream approximately 20 inches in length. The volume of sparks is small with many small and repeating sparklers. The color of the spark stream close to the wheel is red, while :he outer end of the stream is straw-colored.






Figure 10. White cast iron.


Gray cast iron (Fig. 11) produces a stream of sparks about 25 inches in length. It is smali in vol- ume, with fewer sparklers than white cast iron. The sparklers are small and repeating. Part of the stream near the grinding wheel is red, and the outer end of the stream is straw-colored.






Figure 11. Gray cast iron.

The malleable iron spark test (Fig. 12) will pro- duce a spark stream about 30 inches in length. It is of moderate volume, with many small, repeating sparklers toward the end of the stream. The entire stream is straw-colored.





k Figure 12. Malleable iron -.

The wrought iron spark test (Fig. 13) produces a spark stream about 65 inches in length. The stream is of a large volume with few sparklers. The sparklers show up toward the end of the stream and are forked. The stream next to the grinding wheel is straw- colored, while the outer end of the stream is a bright red.

Stainless steel (Fig. 14) produces a spark stream approximately 50 inches in length, of moderate vol- ume, with few sparklers. The sparklers are forked. The stream next to the wheel is straw-colored, while at the end it is white.

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Figure 13. \ITirought iron,







F%xm 14. Alloy steel. i Spark shown is for stainless steel.)

Nicked (Fig. 15) produces a spark stream onlv about 10 inches in length. It is small in volume an2 orange in color. The sparks form wzvv streaks with no sparklers.

.Mowl metd (Fig. 1.5) forms a spark stream al- nmst identical to that of nickel, and must be iden- tified by other means. Copper, brass, bronze, and ‘I xd form no sparks on the grinding wheel, but the) arc easily identified by other means, such as color, appearance, and chip tests.




Figure 15. Nickel.

(See Fig. 16 for low-carbon steel sparks. See also Fig. 17 for high-carbon steel sparks.)

You will find the spark tests easy and convenient to make. They require no special equipment and are adaptable to most any situation.


70 IN.













Fimre 16. Low-carbon steel.*



Fi?,ure 17. High-carbon steel.

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The nitric acid test is the most common test for metal, and it is used only in noncritical situations. For rapid identification of metal. the nitric acid test is one of the ells&t tests to use and requires n” spe- ciaI training in chemistry to perform. It is most help- ful in distinguishing among stainless steel, MOMI,

copper-nickel, and carbon steels. The following sa:et!; precautions must be observed when using or handling acids of any type.

1. Never open more than one container of acid at one time.

2. in mixing, always pour acid slowly into water. .\ewr p”ur mater into acid because an explosion is li‘ke!v to occur.

3,‘If an! acid is spilled. dilute with plenty of water t,, waken it s” that it can safely be swabbed up and disposed of.

-I, IF an acid is spilled on the skin, wash imme- di:ltel\. with large quantities of water. Then wash with a soWion of borax and water.

,5. \‘ear clear-lens safet); goggles to ensure the de- tection of the reaction of metal to an acid test which may be evidenced by a color change, the formation of a deposit, or the development of a spot.

6. Conduct tests in a well venti!ated area. To perform the nitric acid test, place one or two

drops of concentrated (full strength) nitric acid on a meta! surface that hts been cleaned by grinding or filing. Observe the resulting reaction (if any) for about two minutes. Then add three or four drops of water, one drop at a time, and continue observing the reaction. If there is no reaction at all, the test material may be one of the stainless steels. A re- action that results in a browvcolored liquid indicates a plain carbon steel. A reaction producing a brown to black color indicates a gray cast iron or one of the alloy steels containing as its principal element either chromium, molybdenum, or vanadium. Nickel steel reacts to the nitric acid test by the formation of a brown to greenish-black liquid while a steel con- taining tungsten reacts slowly to form a brown- colored liquid with a yellow sediment.

When nonferrous metals and alloys are subject to the nitric acid test, instead of the brown-black colors that usually appear when ferrous metals are tested, various shades of green and blue appear as the ma- terin! dissolves. Except with nickel and Monel, the reaction is vigorous. The reaction of nitric acid on nickel proceeds slowly, developing a pale green color. On !vi”nel, the reaction takes place at about

Heat Treatment

Heat treatment is the operation, or combination of operations, including heating and cooling of a metal in its solid state to develop or enhance a particular desirable mechanical property, such as hardness, toughness, machinability, or uniformity of strength. The theory of heat treatment is based upon the effect that the rate of heating, degree of heat, and the rate of cooling have on the molecular structure of a metal.

There are several forms of heat treating. The forms commonly used for ferrous metals are annealing, nor- malizing, hardening, tempering, and case-hardening.

ANNEALING. The chief purposes of annealing are (1) to relieve internal strains, and (2) to make a metal soft enough for machining. The process is ac- complished by heating the metal to a high temper- ature, holding it at this temperature until the grain structure has been refined, and then allowing it to cool slowly. Both the temperature of the operation and the rate of cooling depend upon the metal being treated, and the purpose for which it is to be used.

Besides rendering metal more workable, annealing can also be used to alter other physical properties, such as magnetism and electrical conductivity. Annealing is often used for softening nonferrous alloys and pure metals after they have been hardened by cold work. Some of these alloys require annealing operations which are different from those for steel.

For ferrous metals, the annealing method most commonly used, if a controlled atmosphere furnace is not available, is to place the metal in a cast iron box, and to cover it with sand or fire clay. Packing this material around the metai prevents oxidation. The box is then placed in the furnace, heated to the proper temperature, held there for a sufficient period, and then allowed to cool slowly in the sealed fur- nace.

For annealing the more common metals, proceed as fo11ows.

CAST IRON. Heat slowly to between 1400” and

the same rate as on ferrous metals, but the character- istic color of the liquid is greenish-blue. Brass reacts vigorously, with the test material changing to a green color. Tin bronze, aluminum bronze, and copper all react vigorously in the nitric acid test with the liquid changing t” a blue-green color. Aluminum and mag- nesium alloys, lead, lead-silver, and lead-tin alloys are soluble in nitric acid, but the blue or green color is lacking.


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ISOO”F, depending on composition. Hold at the spe- ci6c temperature for 30 minutes, and then allow thr metal to cool slowly in the furnace or annealing box.

STAINLESS STEEL ( AUSTESITI~). For full annealing. heat to between 1850°F and 2050°F. Cool rapidly. FOG partial annealing, heat to between 1600” and 1700°F.

COPPER. Heat to 9WF. Quench in water. A tem- perature as low as 500°F will relieve most of the stresses and strains.

ZKC. Heat to 400°F. Cool in open, still air. A~varm~:xr. Heat to 750°F. Cool in open air. This

reduces hardness and strength but increases electri- cal conductivitv.

:; .KEL-COPPER ALLOYS (Ixumrx XioNEL j. Ileat to between 1400” and 1450°F. Cool b!- quenching in water or oil.

NImI:L-h~-’ Y: 1 :...<~hl-IRO~ .*::o NICKEI:MOLYR- ~)~.:~l’hr-C~~o~rl~l~r ALLOYS ( STELLITZ‘). Heat to be- twrrn 7100” and 2150°F. Hold at this temperature a sriitable time, depending on th;cl.ne::. Follow b\ rapid cooling in a quenching medium.

Eanss. Annealing to relieve stress may be accom- plished at a temperature as low as 600°F. Fuller anneals may be accomplished with increased tempcr- atuxs. Larger grain size and loss of strength will re- sult from too high temperatures. Do not anneal at temperatures exceeding 1300’F. Brass should be slowly cooled to room temperature. Either wrap the part with asbestos cloth, or bury in slaked lime or other heat-retarding material.

BRONZE. Heat to 1400°F. Cool in open furnnw to 500”F, or place in a pan to avoid uneven cooling caused by draft.

NORMALIZING. Normalizing, a process similar to annealing, is done for a different purpose. Normal- izing relieves stresses and strains caused by welding, forging work, and uneven cooling of castings. The metal is heated from 50” to 100” above its critical temperature. (See section on hardening.) Then allow the metal to cool evenly in air.

HARDENIXG. Cutting tools, chisels, twist drills, and many other pieces of equipment and tools must be hardened to enable them to retain their cutting edges. Surfaces of roller bearings, parallel blocks, and armor plate must be hardened to prevent weal or penetration. Metals and allow can he hardcncd in several ways. A brief general description of one method of hardening follows.

Each steel has a critical temperntr!rr at wllich there will occur a marked change in the grain st!‘rlc- tze and physical properties. This critical temper-

atwe varies :wrording to tlw carbon content of th< steel. To Ix: hnrdened, strrl mllst br lwaied to n littlr morr than this critical trml’cratrlrc--11, cns~w that ewrv point in it will havr rwchrd critical tcn- peratwr.’ and to allow for sonw slight Iws of hrnt when the metal is transferred from tlrc furnaw to thr cooling medium. It is thee pooled rapidly 1y Ixing quenched in oil, fresh water, or brine. Qxmchin~ firmly fixes the structwal changes which occllrrcd under heating. thus causing the metal to rrmain hard.

If allowed to cool too slowl!;, the ~wtnl will lose its hardness. On the other hand, to prex:eut too rapid quenching (which would result in warping and cracking), it is sometimes nrcessnrv to use oil irl- stead of fresh water or salt water ior Iligh carbon and a!loy steels. Salt water, as opposed to frrsh water, produces greater h:wlness.

TEMPE~IX. The tempering proce~w is ~mplowd as a method of relieving thr strains that arc bror;ght about in steel during the hardening process. ‘~cn- pering makes the metal tougher and less brittle. Tempering is accon~plishrd by heating the hardened steel to a temperature below the critical rang?, hold- ing this temperature for a snfficient time to penctratt the whole piece, and then cooling the piece. In this process, ductility and toughness arc improxwl but tensile strength and hardness arr reduced.

CASE HARDENING. Case burdening is a process of heat treating bv which a hard skin is formed on metal, while thi inner part remains relntivelv soft and tough. ‘4 metal that is originnllv low iu carbon is packed in a sul)stnnre high in carbon content. and heated abovr the critical range. The raw hardcnin~ furnace must givr il uniform heat. Thr lrn~th of timr thr piece is left in the own at this high hat deter- mines the depth to which cnrhon is :&sorlx~d. A com- monly used method of case hardening is to ( 1 ) car- burize the material (an addition of carbon during the treatment), (2) allow it to cool slowly, (3) re- heat, and (4) harden in water. Small pieces such as bolts, nuts, and screws, however, can be dumped into water as soon as they are taken out of the car- burizing furnace.

Hardness Tests

A number of tests are used to measure the physical properties of metals nnd to dcterminc whether a metal meets specification requirements. Sonw of the more common tests arc hardness tests, tensile strength tests, shear strength tests, hem1 tests, fatigue tests, and compression tests. Of primary importance to the worker are the hardness tests.

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in the sections whieb follow In addition, the Sclero- scope and i’ickers hardness tests wil? be covered brirW\-.

IA3wi.i. I~~AIIUNE:SS ‘I-EST. Of all the hardness t~rsts. thr Rockwrll is the one most frequently men- tio~~d. The bait pl-inciple of the Rockwell test (like that of the Brinell. Vickers; Eberbach, Tukron, and Monotron tests) is that a bard material will pene- trate a soft one. This test operates on the principle of measuring the indentation, in a test piece of metal with specified pressure. In the Rockwell tester the hardness mmber is obtained by measuring the de- pression made by a hardened steel ball or a spbero- conical diamond penetrator of a given size under a gi\ren pressure.

\l’ith the normal Mockwel? tester, the 120” sphero- conical penrtrator is wed in conjunction with a 150. kilogram (kg.) weight to make impressions in hard metals. The hardness number obtained is designated Rockweii 6: CRC). For softer metals, the penetrator is R IilG-inch steel ball in conjunction with a 100. kilogram weight. A hardness number obtained under these conditions is designated Rockwell R ( Rb?. Figure 18 illustrates the principle of indenter hard- ness tests. Although the conical penetrator is shown, the principle is the same for a ball penetrator. (The geometry of the indentions would, of couwz, differ slightly.)

\Vith the Rockwell tester, a deadweight, acting through a series of levers, is used to press the ball or cone into the surface of the metal to be tested. Then

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in square millimeters. This number is found by measuring the distance the ball is forced, under a specil%d pressure, into the test piece. The greater the distance, the softer the metal, and the lower the Brine11 hardness number will be. The width of the indentation is measured with a microscope and the hardness number corresponding to this width is found by consulting a chart or table.

The Brine11 hardness machine is of greatest vahle in testing soft and med!nm-hard metals, and in test- ing large pieces. On hard steel the imprint of the

the long pointer is nearly upright (within approx- imately five divisions, plus or minus, on the scale). This step of th- procedure sets the minor load.

4. Turn the zero adjuster. located below the ele- vating wheel, to set the dial zero behind the pointer.

5. Tap the depressor bar downwal-d to release the weights and apply the major load. Watch the pointer until it comes to rest.

6. Turn the crank handle upward and forward, thereby removing the major but not the minor load. This will leave the penetrator in contact with the specimen but not under pressure.

7. Observe where the pointer now comes to rest and read the Rockwell hardness number on the dial. If the test has been made with the l/16 inch ball and a 100 kilogram weight, the reading is taken from the red, or B, scale. If the test has been made with the spheroconical penetrntor and a weight of 150 kilograms, the reading is taken from the black, or C. scale. (In the first example the number is prefixed by Rb, in the latter instance by Rc.)

8. Turn the handwheel to lower the anvil. Tlren remove the test specimen.

BRINELL HARDNESS TEST. The Brinell hardness test- ing machine provides a convenient and reliable hard- ness test. The machine is not suitable, however, for small or thin pieces. This machine has a vertical hy- draulic press design and is generally hand operated, a lever being used to apply the load which forces a IO-millimeter diameter hardened steel or tungsten- carbide ball into the test specimen. For ferrous metals, a 3000-kilogram load is applied. For non- ferrous metals, the load is 500 kilograms. In general, pressure is applied to ferrous metals for 10 seconds, while 30 seconds are required for nonferrous metals. After the pressure has been applied for the appro- priate time, the diameter of the depression produced is measured with a microscope having an ocular scale.

The Brine11 hardness number (Bhn) is the ratio of the load in kilograms to the impressed surface area


the depth of penetration is measured. The softer the metal being tested, the deeper the penetration will be under a given load. The average depth of pene- tration on samples of very soft steel is only about 0.008 inch. The hardness is indicated on a dial, calibrated in the Rockwell B and the Rockwell C hardness scales. The harder the metal, the higher the Rockwell number will he. Ferrous metals are usually tested with the spheroconical penetrator, with hardness numbers being read from the Rock- well C scale. The steel ba!! is used for nonferrous metals and the results are read on the B scale.

With most indenter-type hardness tests, the metal being tested must be sufliciently thick to avoid bul- ging or marking the opposite side. The specimen thickness should be at least 10 times the depth of penetration. It is also essential that the surface of the spwimen be flat and clean. When hardness tests are nvressary on thin material, a superficial Rockwell tester should be employed.

The Rockwell superficial tester differs from the norma! Rockwell tester in the amount of load applied to perform the test, and in the kind of scale used to interpret the results. Where the major loads on the normal tester are 160 and 150 kilograms, the major loads on the superficial tester are 15, 30, and 45 kilo- grams. One division on the dial gage of the normal tester represents a vertical displacement of the in- denter of 0.062 millimeter. One division of the dial gage of the super&&l tester represents a vertical displacement of the indenter of 0.%X millimeter. Hardness scales for the Rockwell superficial tester are the N and T scales. The N scale is used for ma- terials of such hardness that, were they of sufficient thickness, they would be tested with the normal tester using the C scale. The T scale is comparable to the B scale used with the normal tester. In other iespects the normal and superficial Rockwell testers are much alike.

Assuming the sample is properly prepared and the appropriate penetrator and weights are selected, the following step-by-step procedure will indicate how a Rockwell tester is used.

I. Place the piece to be tested on the testing table oi anvil.

2. ~Turn the wheel elevating the testing table until the piece to be tested comes in contact with the test- ing cone or ball. Continue to turn the elevating wheel until the small pointer on the indicating gage is nearly vertical and slightly to the right of the dot,

3. Watching the long pc;inter on the gage, con- tinue raising the work with the elevating wheel until

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ball is 5’) small that it is difficult to read. SCEROSCOPE HJ.RDXESS TEST. If ~O:I were to place

a mattress on the 5oor and drop two rubber balls from the same height. one on the mattress and one

on the floor. the one dropped on the floor will bounce higher. The reason is that the fioor is the ba:der of the two surfaces. This is the principle upon which the Scleroscope works. When using the Scleroscope hardness test, a diamond-pointed hammer is dropped through a guiding glass tube onto the test piece and the rebound (bounce) is checked on a scale. The harder the metal being tested, the higher the hammer will ?-ebound and the higher xvi11 be the number on the scale. The Scleroscope is portable and can be ued to test the hardness of pieces too large to be plxed on the anvil or tables of other machines. An- ~oiher ndv:mtn,gr of the Scleroscope is that it can be ;:rr,~i \viili,,llt dnmngi;lg finished surfaces. The chief c~~~.~c~?~:IIIL;I~c of this machine is its inaccuracy. The ~LYLII~C,Y of the Scleroscope is affected by the follow- iq firtars.

1. So41 pieces do not have the necessary backing and cannot be held rigidly enough to give accurate readings.

2. If large sections are not @d, if they are oddly

shaped, if they have overhanging sections, or if they are hollow, the rexlings may be in error.

3. If oil-hardened parts are tested, oil may creep up the glass tube and inter&-p wii!~l the drop of the diamond-pointed hammer in the instrumert. thus causing an error.

VICWRS HARDNESS TEST. The Vickers test measures hardness by a method similar to that used in the Brine11 test. The indenter, however, is not a ball, hut a square-based diamond pyramid, which makes it accurate for testing thin sheets as well as the hardest steels.

Up to an approximate hardness number of 300, the results of the Vickers and the Brine11 tests are about the same. Above 300, Brine11 accuracy becomes pro- gressively lower. This divergence represents a weak- ness in the Brine11 method; a weakness that is the result of the tendency of the Brine11 indenter ball to flatten under heavy loads. It is for this reason that the Brine11 numbers over 600 are considered to be of doubtful reliability.

If a shop has one type of hardness tester and the specifications indicated by the blueprint are for an- other type, a conversion table, such as Table 2A. may be used to convert the reading.



500 3000 kg kg

--- --- _-- --- --- --- --- --- --- --_ _-- 761* --- 757* --- 74s ___ 733* _-- 122s --- 710* --- 698, --- 682; --- 670+ ___ 353s --- 638* --_ 627*


l/16” Ball bale 100 kg 150 kg --- 70.0 -_- 69.0 --- 68.0 --- 67.5 --- 67.0 --- 66,4 --- 65.9 --- 65.3 --_ 64.7 _-- 64.0 --- 63.3 --- 62.5 --- 61.7 --- 61.0 _-- 60.0 _-- 59.2 --- 58.7



500 3000 kg kg

--- 352 --- 341 --- 331 --- 321 --- 311 --- 302 --- 293 --- 285 --- 277 --- 269 --- 262 --- 255 --- 243 201 241 195 235 189 229 184 223


l/16” Ball Brale 100 kg 150 kg

37.9 36.6

(107.0) (106.0)

99.0 98.2 91.3 96.4

35.5 34.3 33.1 32.1 30.9 29.9 28.8 27.6 26.6 25.3 24.2 22.8 21.7 20.5


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__- @301* --- 57a* --- 555; --- 534’ --- 524* --- 495* _-- 477 --- 46i --- 444 --- 429 _-- 415 _-_ 401 --- 388 --- 315 ___ 363



--- 57.3 --- 56.0 --- 54.7 --- 53.5 --- 52.1 --- 51.0 --- 50.3 --- 48.8 --- 47.2 --- 45.7 --- 44.5 --- 43.1 --- 41.8 --- 40.4 --- 39.1

* Tungsten-carbide ball. () Values beyond nwmal range for scale. 500 kg-non ferrow 3000 kg-ferrous


Plastic materials are being ased increasingly; in some respects, they tend to surpass structural metals. Plastic has proved to be shock resistant, not suscep- tible to salt water corrosion, and i” casting it lends itself to mass production and uniformity of end prod- uct.

CHARACIERISTIC~. Plastics are formed from organic materials geriirallv with some form of carbon as their basic element. Plastics are referred to as syn- thetic material, but this does not necessarily mean that they are inferior to natural material. On the con- trary, they have been designed to perform particular functions that no natural material can perform. Plas- tics can be obtained in a varie? of colors, shapes, and forms. Some plastics are as tough, but not so hard as steel; some are as pliable as rubber; some are more transparent thaE glass; and some are :i@icx iiran aiuminum.

Plastic materials fall into two major divisions- thwmosettings and thermoplastics-and it is neces- sary, if you are goir:g to perform anv kind of work on plastics. to know which of these two you are using.

Thermosettings are tough, brittle, and heat hard- ened. When placed in a flame, thev will not burn readily, if at all. Thermosettings are so hard they re- sist the penetration of a knife blade, and any such



179 211 95.5 (1 175 171 167 164 161 158 156 153 149 146 143 140 135 130

212 201 201 197 192 ia7 la3 179 174 170 167 163 156 149

94.6 93.8 92.8 91.9 so. 7 so. 0 80.0 87.8 86. a 86.0 85.0 82.9 80. a

6.0) 5.2) 3.6) 2.7) 1.5) 0.0) 9.0) 8.0) 6;4) 5.4) 4.4) 3.3) 0.9)

attempt will dull the blade. If the plastic is immersed in hot water and allowed to remain, it will neither absorb moisture nor soften.

Thermoplastics, on the other hand, when exposed to heat, become soft and pliable, or even melt. When cooled, they retain the shape that they took under the application of heat. Some thermoplastics will even absorb a small amount of moisture, if placed in hot water. A knife blade will cut easily into thermo- plastics.

When testing a plastic by inserting it into a fire, you should exercise caution, because thermoplastics wi!l burst into sudden intense flame, and give off obnoxious gases. If you use the fire test, be sure to hold the plastic piece a considerable distance away from you.

MAJOR CROUPS OF PUSTICS. While it is not nec- essary for 1;“” to know the exact chemical compo- sition of the many plastics in Gstence, it will be helpful to have a general idea of the composition of the plastics you are most likely to use. Table 2B pro- vides information on various groups of plastics.

Laminated plastics are made by dipping, spraying, or brushing flat sheets or continuous rolls of paper, fabric, or wood veneer with resins, and then pressing several layers together to get hard, rigid, structural material. The number of layers pressed together into one sheet of laminated plastic will depend upon the

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thickness desired. The choice of paper CRIIWS, wood Machining Operations veneer, or giass fabric will depend upon the end v;e of the product. Paper-base material is thin and q,v;e Machining operations on plastics include cutting brittle, breaking if bent sharpI\-. bat canvas-base pxts from sheet ov rod stock, using various metal material will be difficult to break. As layers are clotting saws; removing stock from parts by rotating added to paper-base material. it gains io strrngth. tools such as in the drill press or the milling machine; but it is never as tough and strong in a laminated cutting moving parts by stationary tools, as on the part as lqws of glass fabric or cnnvas. !:athe; and finishing operations.

ixastic Trade Names in ( )

&XYliC (Lucite, Plexiglass)

Cellulose nitrate (Celluloid)

Polyamide (Nylon)

Polyethylene (Polythene)

Pol~etrafluoroethylene (Teflon)


Advantages and Examples of Uses


Formability; good impact strength; good aging and weathering resistance; high Wanspar- ency, shatter-resistance, riddity. Used for lenses, dials, etc.

Ease of fabrication; relatively high impact strength and toughness; good dimensional stability and resilience; low moisture absorption. Used for tool handles, mallet heads, clock dials, etc.

High resistance to &stortion under load at temperatures up to 300’F; high tensile strength, excellent impact strength at normal temperatures; does not become brittle at temperatures a8 low as minus 70EF; excellent resistance to @soline and oil; low coefficient of friction on metals. Used for synthetic textiles, special types of bearings, etc.

Inert to many solvents and corrosive chemi- cals; flexible and tough over wide tempera- ture range, remains so at temperatures as low as minus 100’F; unusually low moisture absorption and permeability; high electrical resistance; dimensicnally stable atnormal temperatures; ease Of mo1dlng; low cost. Used for wire and cable insulation, and acid resistant clothing.


Extreme chemical inertness; high heat re- sistance; nonadhesive; tough; low coefflclent of friction. Used for preformed packing and gaskets.


Softening pcint of 110” to 220°F; low sci-atch resistance.

Extreme flammabil- lty; poor electrical insulating prop- erties; harder with age; low heat dts- tortio” point.

Absorption of water; large coefficient of expansion; relatively high cost; weather- ing resistance poor.

Low tensile, com- pressive, flexural strength; very high elongation at “or- ma1 temperatures; subject to spuntan- cow cracking when stored ln contact with alcohols, toluene, and sili- cone grease, etc. ; softens at tem- peratures above 200’F; poor abrasion and cut resistance; cannot be bonded unless given special surface treatment.

Not easily cemented; cannot be molded by usual methods; gen- erates toxic fumes at high tempera- tures; high cost.

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Plastic Trade Names in ( )

Phenolformaldehyde (Bakelite, Durez, R..?Si”OX)

Urea-formaldehyde (Beetle, Bakeelite Urea, Plaskon)



Advantages and Examples of Uses


Better permanence characteristics than most plastics; may be used at temperatures from 250” to 475’F; good aging resistance; good electrical insulating properties; not readily flammable, does not support com- bustion; inserts can be firmly embedded; strong, light; low water absorption; low thermal conductivity; gwd chemical re- sistance; economical in production of com- plex shapes; free from cold fiow; relatively insensitive to temperature; low coefficient of thermal expansion; no change In dtmen- sions under a Load for a long time: does not soften at high temperatures or become brittle down to minus 60’F; inexpensive. Used for handles, telephone equipment, electrical insulators, etc.

High degree of transb~cency and light finish; hard surface finish: outstanding electrical properties when used within temperature range of minus IO” to plus 170°F; com- plete resistance to organic solvents; dimensionally stable under moderate load- ings and exposure conditions. Used for instrument dials, electric parts, etc.

SAWING. Several types of saws (budsaw, jigsaw, circular saw) may be used to cut blanks from plastic stock. Speeds should lx watched careh~llp; since al- most none of the hest generated will be carried :wa\ b; the plastic. there is ;~lwnys danger that the tool will be overheated to the point where it will hum the work.

DHII.LING. In drilling plastics, hack the drill rxlt frequently to remove the chips and cool the tool. A liberal application of kerosene will help keep the drill cool. To oh&n n smooth, clean hole, nse paraffin wax on the drill; for the softer plastics, a special coolant may be preferred.

LAlxE OPEnATIoia Lathe operations iw snhstan- tially the same for plastics as for metals, twxpt for type of tool, and the manner in which contact is made with the work. For plastics, set tlw tool slightI! below -enter. Use cutting tools with zero or sliglrtlj~ negative hack rake.

For both thermosettings and thermoplastics. rec. ommended cutting speeds uc 200 to 500 fpm with high speed steel tools, and 500 to 1,500 fpnr with carbide-tipped tools.


Dtflicukt to mold when filled for greatest impact strength. or when In sections less than 3/32-inch thick; can be expanded or contracted by un- usually wet or dry almosphere,

Low impact strength; slight warping with age; poor water resistance.

Fr~rsmrw 01wv.w~~. Plastic must Ix giveu a finishing process to remove tclol marks and pwclucc a clean, smooth surface. Usually sanding and Mling iire sufficient for this purpose.

Surface scratches and pits can be satisfactorilv re- moved by hand sandpapering with dry sandpap& of the grit. Wet sanding can also be done by hnnd, with water and abrasive paper of fine grade. If n large amount of material must be removed, it will he more advantageous to nse sanding wheels or discs.

After pits and scratches have heen removed, the plastic should be huffed. This can be done on a wheel made of loose muslin huffs. HnIBng com- pounds in common use are trip& and ~~xlge. A layer of the compound is deposited on the outside af the huffing whwl. The compound must Ix renewed fre- quently.

Whdn large flat sheets we lacing huffed, be careful not to use too much pressure, nor to hold the work too long in one position. In bufliq small plnstic parts, Iw careful that the wheel does not seize the piece and pull it out of your grasp.

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In metalworking, the c^omrnon measurements are thost. of length. area. md volume. Many of these nudest bc m,ldr with such exactness that a number of ~nwwxin~ tools are available for the purpose. How- CY<-I. [I!<. acrwx~ of the measurements will depend on ihe measuring tools used and one’s ability to use the”1 correctlv.

Pleasuring .tools are also used for inspecting a iinished or partly finished product. Inspecting oper- xtions include testing or checking a piece of work by comparing dimensions given on a drawing or sketch.

Rules and Tapes

There are many d&rent types of measuring tools. Where exact measurements are required, a microm- eter caliper (mike) is used. Such a caliper, when properly used, gives measurements to within ,001 of an inch accuracy. On the other hand, where accuracy is not extremely critical, the common rule or tape will do fqr most measurements.

T?: rype 1 2mvs :xnn of the types of r\l!es aod tapes commonly used. Of all measuring tools. the simplest and most common is the steel rule. This rule is usually 6 or 12 inches in length, although other lengths are available. Steel rules may be flex- ible or nonflexible, but the thinner the rule, the $asier it is to measure accurately, because the divi- Son marks are closer to the work.

Figure I. Types of rules.

Generally a rule has four sets of graduations. one on each edge of each side. The longest lines repre- sent the inch marks. On one edge, each inch is divided into eight equal spaces, so each space repre- sents l/8 inch. The other edge of this side is divided into sixteenths. ‘The 1.14 and l/Z-inch marks are commonly made longer than the smaller division marks to facilitate counting, but the graduations are not, as a rule, numbered individually, as they are sufficiently far apart to be counted without difficulty. The opposite side is similarly divided into 32 and 64 spaces per inch, and it is common practice to number every fourth division for easier reading.

There are many variations of the common rule. Sometimes the graduations are on one side only, sometimes a set of graduations is added across one end for measuring in narrow spaces, and sometimes only the first inch is divided into 64ths, with the re- maining inches divided into 32nds and Eths.

A m&cl or wood folding rule may be used for measuring purposes. These folding rules are usually 2 to 6 feet long. The foldirlg rules cannot be relied on for extrmeiy accurate measurements because a certain amount of play develops at the joints after they have been used for a while.

Steel tapes are made from 6 to about 300 feet in length. The shorter lengths are frequently made with a curved cross section so that they are flexible enough to roll up but remain rigid when extended. Long, flat tapes require support over their full length when measuring, or the natural sag will cause an error in reading.

The j%xihZe-rigid tapes are usually contained in metal cases into which they wind themselves when a button is pressed, or into which they can be easily pushed. A hook is provided at one end to hook over the object being measured so a worker can handle it without assistance. On some models, the outside of


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tb case ca:s !:,e used as one end of the tape when measwin~ ii!&& dimensions.

OVTSIDE Pm: Ih~IETERS. To n,~~,su~e the outside diafilcter of x pilw. it is hrst to NW sonw kind of riejd rule. .4 folrliq 1L.Oodcn rrrlc or a stcol rcrlc is cAisf;rrtor\. for this pmpsr. Liw up tlrr rnd of the ~-rtlc, \vith one side cf thr pip IIS ~IIO\VII in Fis. 1. usins yrul- thiml) its a 5lhp TIWII with tlw one end held in place with voor tlrllmb, swiy the rrdc through an arc and take the maximum leading at tbc other side of tire pipe. I~‘or most practical purposes, tli* nwasuremeut obtained bv using this metliod is sat(sfdciorv. It is necessar\~ that \OII know bow to t,ikc this Ansnrcnxnt. as’ the ontside diamctcr of the !:ii3e is sometimes tbr onI\- dimelrsion $vw on pipe spw:fications.

TII tat;! :1 me:i ~~ema;t i?th 2 ~ovz~n~~~~ riilc. bold the I-& with its edge on th: sur-incc of the object beirrg measured. This will rhionte pardlux and other CJTI-01-s which might resclt due to the thickness of i~ile role. Read the meas~~rement at the gra&ation w!Cch coincides wit!1 the distance to be xxeasured. ,-lltl stair it as beinS so inilni iiidres and fractions nf 211 inci; i Fig. 2:. il\vavs r~ducr fractions to their hi e\t trrms. inr e.xompl~. 618 ii]. would be called ?:i iii. i hmk or eve at tiie end of a tape or rule I\ :~~::.-~>all\. put of ;hr first measured inch.

1XSrIE PIPl,: DI.\1IETEaS. To nlvasllw tlw insidr diameter of a pile with a ndr. as shom~~ in Fig. 5, I~old the rnle so that on? corner of t11r rnlc jlist Iests “11 the inside r)f o~1~’ sidr of thr piy. Tlwn, \vitlr one ellc? t!laS !le!~l i!? ;,I~~[‘, swing t1:c ru!c throiigl, an arc and read tire dinm?er :w-cm t~he maximum iu- side distance This method is satist. ctcr~v for- an ap proximate inside meas~~rement.

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Ec!d the rule or tape :is shown in Fig. 6. Tnke the reading. using the ?-inch graduatiou. jar esanple, as the ?-eCe!-rnce poi:ii. In this case. the coi’rect reading is fm;n~l !I\~ srlbtracting t\v0 inches from the actual !-e;:ili!lg In this \va\~ the first two inches of the tape, i .,= I ‘. ‘i ii :< L! 5 L’< !iai:diP. ~5:~iii ennbie to hold the tape

Figure 6. lieasurinz cixunfrrenw ai a pipe with a tape.

Isxix DrxrExsmss. To takr an inside measure- nirnt. SIICII as the insidr of A box. a ;Jding rule thnt incrlrprate 3 6. or 7-i!?. slidin? rxtension is one of the imt mraiirinq tix~l5. To t&r tlre inside mea- siire1,1r1i:. fixt lilifi!id ill<- folding I-r& to the approx- imate dimrnsion. Then ertend the end of the rule nild read the len$i that it estrnds; adding the length of the extension to the lengtlr on the main bndv of the ru!e ( Fi:. 7). The main hod\- of the rule in ‘Fig. 7 is ii in. 2nd the ertensim is ~~ulletl out !3 3/ 16 in. 1:) this cxt the total inside dimension being men- simd is !6 :?!Ifi in.

In Fig. 8 note i;l the circled insert that tlrr hook at the end of the particuln~ rule shnwn is attached to the rule so that it is fl-w to move sligbtl\-. Wbe~

n outside dimension is taken bv booking tt& end of the rule over an edge, the II& will locate the end of the rule even with the sl!rfacy front wbicb the measurement is being taken. By being free to move, the hook wil! retract awn: from the end of the rule when an inside dimension is taken. To measure an inside dimension using a tape rule, extend the rule between the surfaces a.3 shown, take a reading at the point on the scale where the rule enters the case. and add two inches. The two inches are the width of the case. The total is the inside dimensior IE taken,


Figure 8. Measuring an inside dimension with n tape rule.

Figure 9. Measuring thickness of stock through a hole.

To measure the thickness of stock through a hole with a hook rule, insert the rule through the bole. hold the hook against one face of the stock, and read the thickness at the 0th face (Fig. 9).

OLXIDE DIMENSIOVS. To measure an outside di- mension using a tape rule, hook the rule over the edge of the stock. Pull the tape out until it pxjerts far enor~s$ from the case to permit measuring the required distance. The hook at the end of the rule is designed so that it will locate tbr end of the rule at thr surface from which the mc:~surernmt is bcin~ t~akwr i Fix. 1~0). When taking a nw;rs~~remcr~t of len$l, t!ic tape is held parallel to the Irqthwise edge. For meawring widtlls. the tap should be nt right angles to the lengthwise edge. Rend the di-

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Figure 10. Measuring an outside dimension with a tape rule.

mcnsion of the rule exactly at the edge of the piece being measuwd.

It may not always be possible to hook the end of rhc tape over the edge of stock being measured. In this case. it may be necessary to butt the end of the tap<* against another surface or to hold the rule at a \t;rrtinc: point from which R measurement is to be klhUl.

I>KL.XCE \~EASUBEXESTS. Steel or fiberglass tapes xc ~cnerally used for making long measurements. Srcriw the book end of the tape. Hold the tape reel in the hand and allow it to unwind while walking in the direction in which the measurement is to be taken Stretch the tape with sufficient tension to overcome sagging. At the same time make sure the tape is parallel to an edge or the surface being measured. Read the graduation on the tape by not- ing which line on the tape coincides with the mea- surcment being taken.

Care 01 Rules and Tapes

Rules and tapes should be handled carefully and kept lightly oiled to prwent rust. Neoer allow the edges of measuring devices to become nicked by striking them with hard objects. They should pref- erably be kept in a wooden box when not in use.

To avoid kinking tapes. pnlI them straight out from their cases; do not bend them backward. With the wit&p-type tapes, alwa);s turn the crank clock- wise (turning it backward wili kink or break the tape). With the spring-aid type tapes, guide the tape by hand. If it is allowed to snap back, it may be kinked, twisted, or otherwise damaged. Do not use the hook as a stop. Slow down as vou reach the end.


Simple calipers are used in conjunction with a scale to measure diameters. The calipers most com- monly used are shown in Fig. 11.

Otltsirle coiipers for measuring outside diameters arc bow-legged; those used for inside diameters have straight legs with the feet turnrd outward. Calipers arc adjrlstetl 1)~ pulling or prlshing the legs to open 0~ close them. Fine adjustment is made 1,~ tapping one leg lightly on a hard surfncc to close them, or bv turning them upside down and tapping on the jdint end to open them.

Spring-joint calipers have the legs joined by a strong spring hinge and linked together by a screw and adjustinl: nut. For measuring chamfered cavities (gro”\‘es), or for use over flanges, trar+?r cnlipers are available. They are equipped with a small aus- iliary leaf attached to one of the legs b! a screw (Fig. 11). The measurement is made as with or- dinary calipers; then the leaf is locked to the leg. The legs ma>- then be opened or closed as needed to clear the obstruction. then brought back and locked to the leaf again, therefore restoring them to the original setting.

A different type of caliper is the hertnaphrodite (sometimes called the odd-leg caliper). This caliper has one straight leg ending in a sharp point, some- times removable, and one bow leg. The hermaph- rodite caliper is used chiefly for locating the center of a shaft or for locating a shoulder.

Using Calipers

A caliper is usually rrsed in one of two ways. Either the caliper is set to the dimension of the work and the dimension transferred to a scale, or the caliper is set on a scale and the work machined until it checks with the dimension set up on the caliper. To adjust a caliper to a scale dimension, one leg of the caliper should be held firmly against one end of the scale and the other leg adjusted to the desired dimension. To adjust a caliper to the work, open the legs wider than the work and then bring them down to the work.

Caution: Neoer place a caliper 011 work that is revolving in a machine.

MEASURING THE DIAMETER OF Rowe OR THE THICKNESS OF FLAT STOCK. To measure the diameter of round stock, or the thickness of flat stock. adjust the outside caliper so that !;on feel a slight drag as yo pass it over the stock (see Fig. 12). After the proper “feel” has been attained, meawrr the setting of the caliper with a rule. In rending the mensure- ment, sight over the leg of the caliper after making sure the caliper is set squarely with the face of the rule.

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Figure 11. Simpk (noncalibrated) calipers

MEASURIXG HARD-TO-REACH DIMENSIONS. To mea- sure an almost inaccessible outside dimension, such as the thickness of the bottom of a cup, use an outside trmwfer firm-faint caliper, as shown in Fig. 13. When the proper “feel” is obtained, tighten the lock joint. Then loosen the bioding nnt and open the caliper enough to remove it from the cup. Close the caliper again and tighten the binding nut to seat in the slot at the end of the auxiliary arm. The caliper is now at the original setting, representing the thickness of the bottom of the cup. The caliper setting can now be measured with a rule.

FiFure 12. V’ring outside caliper. To measure a hard-to-reach inside dimension, such

as the internal groove shown in Fig. 14, a lock-joint

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A a

Fignrr 13. h!~asuri,:g thickness of !a,ttom of a cup.

A fl

I‘i<un 14. hl~surin~ hard to reach inside dimensian with an inside caliper.

inside c&per should be used. The procedure fol- Inwed for measuring a hard-to-reach outside dimen- sion is used.

?&.~sm=mc THE DISTAKZ BETWZE~. Two SUB- F.ACES. To measure the distance between two surfaces with an inside caliper, first set the caliper to the ap- proximate distance being measured (Fig. 15). Hold the caliper with one leg in contact with one of the surfaces being measured. Then, as you increase the setting of the caliper, move the other leg from left to right. FwI for the slight drag indicating the pray ‘.l~i . 1~s I( ~!:e -a!iper. Then remove the cali- per an<! ~ne:;suri the setting with a rule.


Figurr 15. Measuring distance b&veer. tuw surfaces with an inside caliper.

L~E.~SCHIST. HOLE DIAMETEERS. To measure the dinm- eter of R hole with an inside caliper, hold the cali- per with one leg in contact with one side of the hole (Fig. 16) and, as you increase the setting, move the other leg from left to right, and in and out of the hair. When you have found the point of largest diam- eter, remove the caliper and measure the caliper setting with a role.

Figure 16. hleasorinr: inside dinmdcr with an inside caliper.

SFXTIW A COMHINATION FIRM-JOINT CALIPER. To set a combination firm-joint caliper with n rule, when the legs are in position for outside measurements, grasp the caliper with both hands, as shown in A, Fig. 17, and adjust both ;egs to the approximate set- ting. By adjusting both legs, the shape of the tool will be approximately symmetrical. Thus, it will maintain its balance and be easier to handle.

Figure 17. Setting- a combination firm-joint caliper

Check this approximate setting ns shown in 13, Fig. 17. Sight squarely across the leg nt the graduations on the rule to get the exact setting required.

If it is necessary to decrease or increase the setting, tap one leg of the caliper, as shown in Fig. 18. The arrow indicates the change in setting that will take place.

Figure 18. 13rcrrwin): nnd increasing setting of a firm-joint caliper.

When the caliper is set for inside measurements, the same directions for adjusting thr setting apply. Figure 19 shows how the end of the rule and one

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leg of the caliper are rested on the bench top so that they are exactly even with each other when the read- ing is taken.

S~mxc OUTSIDE AND INSIDE SPRING CALIPERS. To set a particular reading on an outside spring caliper,

first open the caliper to the approximate setting. Then, as shown in Fig. 20, place one leg over the end of the rule, steadying it with the index finger. Make the final setting by sighting over the other leg of the caliper, squars!y with the face of the rx!e at the read- ing, and turning the knurled adjusting nut until the desired setting is obtained.

Figure 19. Setting combination firm-joint caliper for inside measulerrlentr.

Figure 20. Setting outside spring caliper.

To set an inside spring caliper to 2 particular read- ing, place both caliper and r&z on a flat surface, as shown in Fig. 21. The rule must be held sqwre!y or normally (SC degrees in both directions) to the sur- face to ensure accuracy. Adjust the knurled adjusting nut, reading the setting on the rule with line of sight normal to the face of the rule at the reading.


To .4x0-z. TG transfer a measurement from one spring caliper to another, hold the calipers as shown in Fig. 22. &Vote that one finger is extended to steady the point of contact of the two lower caliper legs. I” this illustration the inside caliper is being adjusted to the size of the outside caliper. As careful rneasure- ments with caliper depend on one’s sense of touch (“feel”) caliprr~s are best held lightly. When a slight dr ag is noticed, the caliper is at the proper setting.

Figure 21. Setting inside spring caliper.

Figure 22. Transferring measurement from PO outside to an inside caliper.

Core of Calipers

Keep calipers clean and lightly oiled, but do not overoil the joint of firm-joint calipers or you may have difficulty in keeping them tight. Do not throw them around or use them for screwdrivers or pry bars. Even a slight force may spring the legs of a caliper so that other measurements made with it are never accurate. El-member, calir;ers are measuring instruments and must be used only for the purpose for which they are intended.

Slide Calipers

The main disadvantage of using ordinary calipers is that they do not give a direct reading of a caliper setting. As explained previously, you must measure a caliper setting with a m!e. To overcome this dis- advantage, use slide calipers (Fig. 23 j. This in+>- ment is sometimes called a caliper rule.

Slide calipers can be used for measuring outside, inside, and other dimensions. One side of the cal- iper is used as a measuring rule, while the scale on the opposite side is used in measuring outside and inside dimensions. Graduations on both scales are in inches and fractions thereof. A locking screw is incorporated to hold the slide caliper jaws in position during use. Stamped on the frame are two words, “IN” and “O’UT,” which are used in reading the scale while making inside and outside measurements, respectively.

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/LYi x.





Figuurr 23. Pocket slide DI caliper rule,

‘1’0 IIIWS~W~ tile otrisirle diameter of round stock, iii tilt, !Ilickness ot iiat stock, move the jaws of the caliper into firm contact with the surface of the stock. Read the measurement at thp reference line stamped OUT (Fig. 24).

\Yhen measuring the inside diameter of a hole, or the distance between two surfaces; insert only the rounded tips of the caliper jaws into the hole or be- tween the txvo surfaces ( Fig. 25 ) Read the measure- ment on the reference line stamped IN.

Figure 24. hleasuring outside dimension with 2 pocket slide caliper.

Figure 25. Measurina inside dimension xvith a slide caliper.

Note that two reference lines are needed if the caliper is to measure both outside and inside di- mensions, and that thev are separated by an amount equal to the outside dimension of the rounded tips when the caliper is closed.

Pock& models of slide calipers are commonly made in 3- and 5.in. sizes and are graduated to read in 32nds and 64ths. Pocket slide calipers are valuable when extreme precision is not required. They are frequentlv used for duplicating work when the ex- pense of hxed gages is not warranted.

Vernier Caliper

A oernier caliper (Fig. 26) consists of an L-shaped member with R scale engraved on the long shank. A sliding member is free to move on the bar and carries a jaw which matches the arm of an L. The vernier scale is engraved on a small plate that is attached to the sliding member.

The most distinct advantage of the vernier caliper, over other types of calipers, is its ability to provide very nccurate measurements over a large range. It can be used for both internal and external surfaces. Pocket models usually measwe from zero to 3 inches. bnt sizes are available all the way to 4 feet. In using the vernier caliper, you must be able to read a ver- nier scale.

P~IXCIFLES OF THE VERNIER SCALE. It would be possible to etch graduations l/1000 inch (0.001 in. ) apart on a steel rule or sliding caliper, as shown in Fig. 27. The enlarged illustration shows two grad- uated scales; the top scale has divisions which are 0.025 inches apart, and the small sliding lower scale has 25 divisions, each equal to 0.001 inch graduations which can divide any of the main scale divisions of 0.025 inch into 25 parts. When the first graduation marked “0” on this smalt scale aligns with a grad- uation on the main scale, the last or 25th will also align with a graduation on the main scale as shown in Fig. 27. Therefore, the small 0.00 graduations are not significant in this position. Rut when the zero graduation does not align with n graduation on the main scale, it can be readily determined how many thousandths the zero missed the 0.025 inch grad- uation by counting the misaligned graduation at either end of the small scale. When the zero or index line 011 the sliding scale does not quite reach the graduation, the amoust of misalignment must be subtracted, but when it passes the 0.025 graduation from which the reading is made, it must be added. This illustrates the simple arrangement to increase

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FIXED JAW Figwe 26. Vernier caliper.

the :ICCII~,IC~~ of n common scale. Unfortunately, the O.C!Oi inch qndlutions are not too !egible and so the s,~~sk~r is n:rt practical. A \wnier arrangement over- c’itii~ci~ ihis ild~lem.

l’i:ii\;!ikl SCA1.E ~RR.OKXKTXT. The main differ- enrc betwren the vernier scale and the arrangement sho\vn in Fig. 2i is the spacing of the 25 divisions. Instead of 25 graduations crowded within the space of one n:ain scale division, the vernier graduations are arranged at intervals exactly 0.001 inch less than the main scale graduations as shown in Fig. 28. This arrangement results in an accumulation of misalign- ments, starting with the first vernier graduation past the zero so that each may be marked as shown with a number representing the space in thousandths to the next upper scale graduation. For example, if the

zero index line would be moved past the 8 inch grad- uation until the vernier graduation number 5 aligned with the next mair. scale graduation, the exact read- ing would be 8 inches plus 0.005 or 8.005 inches.

READING A VERPXER CALIPER. Figure 29 shows a bar 1 inch long divided by graduations into 40 parts so that each graduation indicates one-fortieth of an inch (0.025 inch). Every fourth graduation is num- bered; each number indicates tenths of an inch (4 x 0.025 inch). The vernier, which slides along the bar, is graduated into 25 divisions which together are as long as 24 divisions on the bar. Each division of the vernier is 0.001 inch smaller than each division on the bar. Verniers that are calibrated as just ex- plained are known as English-measure verniers. The metric-measure vernier is read the same, except that the units of measurement are in millimeters.

Figure 27. Vernier scale principle.


Figure 28. Expanded view, of vernier scale

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Figure 29. En,dish rwacure vernier scale

A, Fig. 30 shows the English measure vernier cal- iper. B. Fig, 30 shows an enlarged view of the w-“ier section As voo can see in the illustration, when the ZPPI on the’ vernier coincides with the l-inch mark, no other lines coincide until the 25th mark on the vc,rnicr.

7.0 read the caliper io C, Fig. 30, write down in a u)l!~mo tlw number of inches ( 1.000 in.), of tenths of an inc!) (0.400 in.), and of thousandths of an inch that the zero mark on the vernier is from the zero mark on the I-a:e. Because the zero mark on the ver- nier is a little past a 0.025 in. mark, write down the 0.025 in., and then note the !lighest number on thr vern;er where a line on the vernier coincides with one on the rule. In this case it is at the 0.011 in. line on the vernier, so you also write the 0.011 in. in the column, which will then Iook like the following.

I.000 in. ,400 in. ,025 in. ,011 in.

1.496 in.

The reading on the caliper shown in C, Fig. 30 is 1.4.36 in. and was obtained by adding four separate readings. .4fter a little practice voo will be able to make these calculations mentallv:

,Ijffi; ~ *fff;,, 1 *i!G& 12” or 300 mm . / :300"::: 7:62 mm. 24" or 600 mm. .300"... 7.62 mm. 36" or 600 mm. .500"... 12.70 mm.

Now try to rend the settings of the two verniers shown in D and E, Fig. 30. Follow the above pro- cedure. You should read 2.350 in. on D and 2.368 in. on E.

To read a metric-measure vernier, note the nombel of millimeters and the 0.25 millimeter, if the setting permits, that the zero on the vernier has moved from the zero on the scale. Then add the nomber of how dredths of a millimeter indicated by the line on the vernirr that coincides with a line on the scale.

For example, A, Fig. 31 shows the zero graduation on the vernier coinciding with a 0.5.mm graduation on the scale resulting in a 38.50 mm reading. The reading in B, Fig. 31 indicates that 0.08 mm should be added to the scale reading ;and results in 38.00 mm + 0.50 mm + 0.08 mm = 38.58 mm.

If R vernier caliper is calibrated in either English measure or in metric measure, usually one side will be calibrated to take outside measurements and the other to take inside mcasrnements directly. The ver- nier plate for inside measurements is set to compen- sate for the thickness of the measuring points of the tools. But if n vernier caliper is calibrated for both English and metric measure, one of the scales will appear on one side and one on the other. Then it will be necessary. when taking inside measurements over the measuring points, to add certain amounts to allow for their thickness. For example, Table 3 shows the amounts to be added for various sizes of vernier calipers.

OOTSIDE SURFACE MEASUREIMENTS. To measure the distance between outside surfaces or the outside di- ameter of round stock with a vernier caliper, steady the stock with one hand and hold the caliper in the other, as shown in Fig. 32. In the illustration, the clamping screws are at A and B; the horizontal ad- justing screw nut is at C. With A and B loose, slide the movable jaw toward the piece being measured until it is ahnost in contact. Then tighten A to make C operative. With C, adjust the movable jaw to the proper feel and secure the setting with B. The read- ing can then be taken as previously explained.

I:VSIDE SURFACE MEASUREMF.NTS. To measure the distance between inside surfaces, or the inside diam- eter of a hole, with s vernier onliper, use the scale ~ marked inside. Figure 33 shows the measuring points in place. Remember that if you are “sing R vernier caliper with both metric and English scales, the sales appear on opposite sides of the caliper and apply ,:mly to ootslde measurements. Then, to get correct inside measurements, you add to the actual reading the measoring point allowance for the size

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0 5 io 15 20 MEiiW MEASURF VEWER

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Fignan 33. Mcawring ir.sidc diameter with a vrrnier cn!kcr

of caliper you are using. Take this ullowance fro”. Table 3, “T from the man”factwer’s instrwtions. The “ctwl measurement in this raw is made in the same manner as taking ;,n outside ~rrensurement.


Care of Vernier Calipers

The it~si& faws “f tlw jaws and thr wtsidc: “f the tills 1nlls1~ br treated wihr great cilrc. If the\; become ~vorn. 01 thr jaws Ixnt, tlw tlrol \\+I] rr,, Im~fiw fiivc ;~ccrnxtr rdinp The xxrwacy “f VWniel- c;dipers should be checked periodically by measuring an ob- ject of knnwn dimensir”~. \‘er”ier c:dipers can be ad- justed when they RX: not xowate, but the n~m”- factwer‘s recommendations for this adjmtment must be followed. Keel> vernier calipers lightI\, “iled to pre\F”t rust ;d keep thcnl storfd a\wy from henV> tools.


I” mrlch wider 11.w thaII the vernier caliper is the n~icwmctrr comm$, called thr ndic. It is inqx”- tant that a person who is wxking witll rnuchiirer\; or in a machine shol~ thoi-oughlv m&rstands the mc- chanical principles, co”stnAon. me, a”d care “f the micrometer. Figure 34 shows an outside microm- eler coli~m with the wriv”s I>::+ clcul!; indicated. Uicrometers are used t” measurr distances to the “ear& “ne thowandth “f 3” inch The measurement is usr~nlly cxpressrd or written as n decimal; s” you mrrst know the method “f writing and rading deci- rnals.

Types of Micrometers

Thcrr :w thrw tylxs of “licromrtcl-s that itw commonly ~~sctl: the “rltsidc micrometer caliper (in- cluding tlw ;‘3’ thread micrometer), the irrside micromett~ aiid the depth micronwtrr. (Set Figs. 34 and 35. )



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Fipxr 33. Type id micmmetcr~.

The orc!r-iric micromefer is toed for measlwing orlt- side dimensions_ such as thr diameter of a piece of rorwd stock. The .SC:CW timmi micromrter is used to deiern1inr the pitch dia;mier of scre\vs. The ine/c tniumwfer is tmd fw meaxxinq inside dimensions. iis for wwiplr. ihe inside diameter of R tiuhe or hole. the hoie of a c\~!indrr 01 the width of a recess. 1’1~ dq;th nii!~?~>l?Ietcr is !Wd hr nicxiirin~ the dept!1 of hil!iY :,i I!‘C(ISSCC.

011e inch nricr-mnrtcr is from 0 to 1 inch In otha \\~w<ls. ill (‘:n, 111~ 1wd 1)11 \\ork \\ael-e the pxt to I,<, 1n1x511r-~d is me inch 01 1~s. 4 two inch micrrmlei~I 113s i, r;n,!$ of from I to ” inches. and \Vill ,nenSlliC onl\~ work between me and two inches thick; a six inch micrometer has a ransc of from 5 to 6 inches, and will ~n~asn~‘c onlv work between five and six inches thick. It is nec&sar~, therefore, when you are selecting a micrometer, that you first find the q- proximate size of the work to the nearest inch, and then select a micrometer ihat will fit it. For exampZe, to find thr csnct diameter of n piece of hound stock, :m: :I rnk and find the approximate diameter of the stock. If it is found to be appl-oximntely 3 l/4 inches, 2 nricroinetcr wit11 :L “, to 4 inch range would I;e re- quired to measuw the exact dinmctcr. Similarly, with inside and depth micl-omrters, rods of sllitable Irngths must be fitted into tile tool ta get the ap proximate dimension within an inr’l, after which the exact measurement is read bv turning the thimble. The size of a micrometer in&cates the size of the largest work it will measure.

HEA~ISC A ~I!CROXIETER CAIJFEK The sleeve and thimbie scales of the micrometer caliper have heen enlarged in Fig. 36. To understand these scales, you need to know that the threaded section on the spirr- die_ \vhich revolves, has 40 threads per inch. There- fore, every time the thimble completes n revolution, the spindle advances or recedes l/40 inch (0.023

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Tc,te iii the iiiusiriliion that the hwizontai line 011 ilit, slwve is divided into 40 equal parts per inch k:\~l.rJ~ fourth g”.“d”‘“tio” is I”“nbrTrd 1, 2. :i. 4. and 10 on. rcpresrnting 0.1W iii.. tP.?%K) in., aud so 011. \~‘hen YOU turn the thimble so that its edge is over the first sleeve line past the “0” on the thimble scale. the spindIe has opened 0.0% in. If yx~ turn the spitIdle to the SWORN mark. it has lno\red to 0.025 in. plus ii.025 ii). or Q.QSO in. YOri use the SG!le On th? ~hintble to complete !.our reading when the edge of the thimble stops between gxduntid lines. This stmii~ is &\-i&d into -75 equal parts, each part rep- ;.5t~:ilIi1~ i/23ih of il iurn; and i:ZSih of 0.025 in is PWi! iii. ‘is vo1: cm set-. ever\- fifth line on the :!,iri,l,i<s sci(ic.is markrd 5. iii. i.5. and so on. The illitiiiilr’ scale. i!iei.efore. permits vou to take ver\ ~w~IIs.~~~~ rr,:.dirigs to the thousand&s of an inch, and. :uri:v W:I inn estimate between the divisions on the t!!il:ible scalr, fairly accurate readings to the ten ihwlwndth nf ar, inch are possible.

I’!q~:^tir<z 37 \~ill help YOU understand how to take it cr~r;~pIete micrometer reading. Count the units on the thimble scale and add ibem to tbt reading ON ibe &eve scale. The readiq in the ilhlstration shows d sleeve reading of O.-150 in. (the thimble having stopped slight!v mere than halfwav beiween 2 and 3 on the .sleeve) with the IOtb line on the thimble scale coinciding with the horizontal sleeve line. Nom- her IO on this scale means that the spindle has moved awav fmm the ltnvil an additional 10 s 0.001 or 0.010 in. Add this amouct to the 0.250 in. slew? reading, and the tota: distance is 0.260 in.

Figure 37. kading a miiromitr~ cdipm

I?ead each of the micrometrr settings irr Fig. 3R so thaP im cm be swr of vourreif whe I yen begin to nse ;his tad on the job. The correct readings are given ioI?ow!ng the $+lure 5” that \:<I11 can check i-carself.


Amwets for checking-

1. = 0.327 4. = 0.438 2. = 0.229 5. = 0.137 3. = 0.428 6. = 0.336

Figure 38. Micrometer-rending exercises.

Figure 39 shows a reaiing in which the horizontal line falls between two graduations on the thimble scale and is closer to the 15 graduation than it is to the 14. To read this to three decimal places. see Fig. 39 and calculation A. To read it to four decimal places estimate the number of tenths of the distance betwrer. thimbie-scale graduations the horizontal line has fallen. Each tenth of this distance equals one ten-thousandth (O.OOOl) of an inch. Add the ten-thousandths to the reading as shown in the cal- culations of B, Fig. 39.

Figure 39. Enterpulating a micrometer reading.

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Figure 41. Wendin:: a wrnirr micrometer diprr

Fig. 42, may be used. Note that the figures on both thr tl~irnble and thr barrel arc reversed, increasing in the opposite dircctiun from thosr on an outside micrometer caliper-. This is because tbis microme!:er reads inside measurements. Therefol-e, as you turn the thimble clockwise on this micrometer. the mea- suring surfaces mow farther apwt and the reading increases. (On an outside micrometer caliper, as you turn the thimble clockwise, tire measuring surfaces ~nove closer together and the reading decreases.)

For holes from two inches up to several feet in dinmeter_ select tile inside micrometer having extew sion rods whose range includes the required dimen- sion. The extension rod marked 6-7; for example,

whrr~ inserted into the head of the micrometer, will me;~s~w~ inside diameters from 6 to 7 inches. Tbc shorrldrl- on thr rod m,,st se3t pwperl~ to ens,ire ii conwt~ reading. For large menswemcnts, 1%. Fig. 42, show:i hew hoth Imrds arc IISC~ to srt the microm.. eter for cbecking n diameter. Hold one end in place witb one hand 21s you feel for the maximum possible setting I)!, moving the other end from left to right,

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and in and o”t of the hole with the other hand. Wherl no left-to-right movement is possible, and a slight drag is noticed on the in-and-out-swing, take the reading.

Xil:~wn”w Houli~ Sroca. \Vhwr mensurin~ thv diameter of a s~nall piece of roilnd stock, hoid thr stock to be measwed in one hand. Hold the micro- meter in the other hand so that the thimble rests be- tween the thumb and the forefinger (see Fig. 43). The third finger is the” in a position to hold the frame against the palm of the hand. The frame is supporte’d in tbis manner and makes it easy to guide the wxk over the anvil. The thumb and forefinger we i” position to turn the thimble either directly or thro+ the ratchet and bring the spindle over :l@nct the surface being nwasnred.

Figure 43. Measuring round stock with a micrometer caliper.

Turn the spindle down to contact by feel, or else tie the ratchet stop. Your feel should produce the same colttact pressure and therefore the same read- ing as that produced when the ratchet stop is used. Develop your feel by measuring a certain dimension both with and without the aid of the ratchet stop. When you have the correct feel, you will get the same readings bv hoth methods.

In measuring~round stock the feel must be ver> light becawz there is onlv a line contact between the spindle and the stock and the anvil and the stock. Therefore, the contact area is exceptionally small, callsing a proportionally high contact pressure per “nit of area. This tends to give a reading smaller than the trw readingI unless the light feel is wed. Moreover, in meaxring n hall from n hall bearing. the contact is at onlv two points, so the contact area is again verb- small, which results in a tremendow pre~wre pe; “nit of area. This condition rrq”ires only the lightest possible contact presswe to give a true reading.

Hold the micrometer lightly and for only as long as is necessary to make the measurement. Wrapping the hand around it or holding it for too long a time will cawc expansion of the “MaI and will introduce errors i” nwnswement. IXexl the setting on thr thin- ble scale (if the object is small) withorlt rc”“wi”g the micrometer caliper from :!w object.

hfe.wJ”rNG A FLAT SURFACE. When measuring a flat surface with a micrometer caliper, the entire area of both the anvil and the spindle is in contact with the surface being measured. This cnuses n propor- tionally low contact pressure per “nit of area. There- fore the feel should be slightly heavier than \&en measuring round stock.

On large fZat work, it is necessary to !~nve the work stationary and positioned to permit acces.s for the micrometer. The proper method of holding a micl-om- eter when checking :I part too large to he held i” one hand is shown in Fig. 44. The frame is held 1)) cme hand to position it and to locate it sqwue to the measured surface. The other hand operates the thim- ble either directly or through the ratchet. A large, flat surface should be measured in several places to determine the amount of variation. It is good prac- tice to lock the spindle in place with the locknut before removing the micrometer from the part being measured. After removal of the micrometer the measurement indicated on the thimble scale can then be read.

To retain a particular setting, in cases where sev- eral pieces are to be gaged, lock the spindle in place with the locknut. When n piece is gaged with a micrometer whose spindle is locked to a partic&u setting, the piece can quickly be identified as over- size, correct size, or undersize.

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Figure 46. Sliding ‘I’-bevel.

square witb a slotted beveled blade. Blades are no-- mall)- six or right inches long. The sliding T-bevel is nsed for laying out angles other than I-ight angles. and for testing constructed angles such as brvelc. These squares are made with either \vood or metal handles.

ADJUST~~E~TS. To adjust a sliding T-bevel to a dr- sired settins, loosen the blade screw. at tlw mund end of the handle, just enough to permit the bl:lde to slid? along its slot and to rotate with slight fric- tion.

To set the blade nt a 45degree angle, hold the handle against R framing sqrtare as shown in A, Fig. 47, with the blade intersecting equal graduations on th,- tongue and blade of the square; or hold the bevel against the edges of a 49degree drafting tri- angle, as shown in R; Fig. 47. When using drafting triangles for setting :a. s-?-.,,~ I- IA:-- T bevel, different size trianglr must be wed for each different setting. .1 45.degree angle can also be set by using the squaring head of a cornhination set as shown in C:. Fig. 47.

A sliding T-bevel can be set to anv desired angle by using a protractor. Loosen thr i-ilnde screw as b&xc, ;u~d hold the he\el with the bladr passing througii the grxduation selected and tlw r:entcr of the protr~tclor as shown in 1). Fig. 47.

coNS.rHIIcr13rl ANC1.K \~ER!FIcA.I.rOZ. ‘I‘:: test il cha”lfcr or bed for trrlrl!ess ) set the T-bC\d to tlw required angle, and bold the handle to Ihr working fwr of thr stock being testixi. Face ik sourw of light.

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c D ~i~nrr 47. hdjusting sliding: T-bevel to a desired setting

and \vitb the blade brought into contact with the swface to hr test-d. pass the blade along the length of the surface (Fig. 48). The appearance of iight betwem the blade and the surface of the stock in- dicates where the angle is not correct Figure 48 indicates the checking of a bevel. but testing the trueness of a chamier is accomplished in the same wa.y.

Figore 48. Testing tmerress of a bevel,

Combination Square

.4 combination square is equipped with moving heads called a syuare hcnd, protractor head, and a cen&r head. These combine the functions of several tools, and serve a wide variety of purposes. (See Figs. 49 and 50.) Normally only one head is used at a time.

The square lxxx1 may be adjusted to any position along the scale and clamped securely in place. The combination square can thus serve as a depth gage, height gage, or scribing gage. Two of the faces of the head are ground at right ~.ngIrs to each other,


and a third face at 4.5 degrees. .4 small spirit level is built into the head for checkir!g whether surfaces are plumb, and a small scriber is housed in a hole in the end of the head for marking I:l);out lines.

The center I~eatl can be slid onto the blade in place of the squxe head. This is a V-shaped member so designed that the center uf the 90.degree \’ will lie exactly along one edge of the blade. This attach- ment is useful when locating the exact center of round stock.

The protractor head, commonly called R bevel pro- tractor, can be attached to the scale, adjusted to any position on it, and turned and locked at any desired angle. Angular graduations usually read from 0 to 180 degrees both ways, permitting the supplement of the angle to be read. A spirit level may be included on some models, forming, in effect. nn adjustable lwel to show any required degree.

Core of Squares

Make certain that the blades, heads, dials, and all accessories are clean. Apply a light coat of oil on all metal surfaces to prevent rusting when not in use. Do noi xse sqwires for pcrposes other than those intended. When storing squares or bevels for long periods of time, apply a liberal amount of oil or rust- preventive compound to all surfaces, wrap in oiled paper or cloth, and place in containers or on racks away from other tools.





_---- --

I?igure 49. Combination square Set.

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Thrw are a number of miscellnneous gages. The dqdh gage, fcclrr gag’, tllre:ld gag’, telescq>illg ~“se, dividers. and plrmrb bob ;ue arnon~~ sonw of the ~q:cs discrnsrd in this chapter.

head has a clamping screw so that it may bc clamped in any position The sliding lrr:~d has a flat bnsc which is pq>endirrllar to the axis of the rule :lnd rmges in size from 2 to 2 518 inches in width

and from l/8 to l/4 idl in thickness. The tnicrov~c~ &qcl,th gage consists of a flat basr

attached to the b:wel (sleeve) of a micrometer head. These gages have R range from 0 to 9 inches, de- pending on the length of extension rod used. The hollow micrometer screw (the threads on which the thimble rotates) itself 1x1s a range of either l/2 or i inch. Some are provided with a ratchet stop. Tbc flat base ranges in size from 2 to fi inches. Several extension rods are normally supplied with this typr of gage.

To measure the depth of a hole or slot with ren- sonnble accurac), use a depth gage as shown in A, Fig. 52. Hold the body of the dcptb gage aguixt thr surface from whiclr the depth is to be mrasr~rrd and




Figure 51. Types of kpth pages

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Figure 52. Using depth gages.

cxtrnti the scnlr into the hole or slot. Tighten the setscxv to maintain the setting. \Vithdmw the tool fro!,~ the vdc md read tlrp depth on the scale.

To mwsiiw the depth of R hole or slot with more ;~~~cnra~~v thnn is possible with an ordinary depth I-‘:I~‘, plw :I \-emit-r depth gag’ over the slot, RS :l~xn~ in H, Fig. j2. Safe that the clamping screws ;w ;tt S and Y; and the horizontal adjusting screw lllit is at Z. Kit11 X and Y loose, slide the scale down htu the slot being measured until it is almost in con- tact. when tighten X to make Z operative. With Z, adjust the scale to the proper feel and secure the setting with Y. (By proper feel is meant the adjEst- nm:t at which you first notice contact between the end of the scale and the bottom of the slot.) Then read the setting as previously described under Read- ing a Vernier Scale.

To set the vernier depth gage to n particnIar set- ting, loosen both setscrews at S and at Y and slide the scale through the gqe to tbr approximate set- ting. Tighten the setscrew nt S, turn the knurled nut at Z until the desired setting is made; and tighten the setscrew at Y to hold the setting.

To measure the depth of a hole or slot, as shown in C, Fig. 52, with more accuracy than is possible with either an ordinary depth gage or a vernier deptfl gage; place n micrometer depth gage over the slot and adjust the thimble until the contact of the spindle causes the ratchet step to slip. Remove the micrometer from the work and read the micrometer. Remember, if extension rods are used, the total depth reading will he the sum of the length of the rods plus the rending on the micrometer.

Surface Gage

Z surface gage is a measuring tool genernlly 11s2d to transfer- measrrrcments to work 1~ swihing n line, zxl to indicate the accurac!- or p&allelism of sm. f aces.

GAGi PINS Figure 53. Surface gage.

The surface gage (Fig. 53) consists of a base with an adjustable spindle to which may be clamped a scriber or an indicator. Surface gages ax made in seve:al sizes and are classified by the length of the spindle, the smallest spindle being 4 inches long, the average 9 to 12 inches long and the largest 18 inches. The s&her is fastened to the spindle with a clamp. The bottom and the front end of the base of the surface gage have deep V-grooves cut in them, which allow the gage to be seated on n cylindrical surface.

The spindle of a surface gage may be adjusted to any position with respect to the base and tightened in place with the spindle nut. The rocket adjusting screw provides for the finer adjustment of the spin- dle by pivoting the spindle rocket bracket. The scriber can be positioned at any height and in any desired direction on the spindle by tightening the scriber nut. The scriber may also be mounted directly in the spindle nut mounting, in place of the spindle, and used where the working space is limited and the height of the work is within range of the scriber.

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To set a surface gage for height; first wipe off the top of a layout table or surface plate and tbe bottom of the surface gage. Use either a combination square or it rule with rule holder to get the measurement. A rule aiorre cannot be held securely without wobbling and consequentl!; no error in setting generally re- sults. Because a combination square is generally available, its use for setting a surface gage is ex- pEained in this section.

Piace the squaring head of a combination square on a flat surface, as shown in Fig. .54; and secure the scale so that the end is in contact with the surface. \inve the surface gage into position and set the smhel- onto the spindle. flake the final adjustment fc:r the watt height required (4 112 inches in this c:\w) with the n’djusting SCT~W on the base of the “:!;<C’.


Figure 54. Setting a surface gage tc height.

Surface Plate

A surface plate provides a true, smooth, p!ane sur- face. It is a flat-topped steel or cast iron plate that is heaviiv ribbed and reinforced on the underside (Fig. i5). It is of&r? used in conjunction with a sur- face gage as a level base on which the gage and part to be measured are placed to obtain accurate measurements. The surface plate can also be :Ised for testing parts that must have flat surfaces.

To test a surface for flatness, carefully clean it and wnove alI burrs. Then place the surface of the object on a Bat area such as the surface plate in Fig. 56. Any rocking motion that is apparent will indicate a variance from flatness of the piece being tested.

Figure 55. Surface plate,

Figure 56. Testing a surface for flatness

For very fine work, lightly coat the surface plate with prussian blue (bearing blue) and move the piece being tested across the blue surface (Fig. 57). The low spots on the surface being tested will not take the blue; the high spots will take the blue (Fig. CT\ “1 ,.

To determine how much variation there is from flatness-and where it is-you can insert leaves of a thickness gage to determine the amount of variation of flatness. Remember to add the thickness of all leaves together to get the total variation (Fig. 58).

A surface also may be tested for flatness with a straightedge. To do this, clean the surface thoroughly and hold the straightedge on the surface in several places as you look toward a source of light. The light showing between the surface being tested and the straigiltedge will reveal the low spots.

Figure 57. Using prussian blue to aid in iestiq a Hat surface.

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Figure- 58. Checkir.g conformit); of d flat surface.

CcrP@ of Surfcm3 Plates

the i~.irface plate sboold be covered when not in UP TV prrvent scratching. nicking: and denting. It must lie handled cnreiull,v to prevent warping (twist- iil!!~ i ,,>>.T\. C,~,,? we thr surface plate as an anvil or ;,,,!,~!l~i~~~~~!i--escept fnr precision layout work (mark- iii!!, di;<i wmring~.

Thickness (Feeler) Gage

Tk.ickne.ss (feeler) gages are used {or checking and mea5urir.g small openiqs such as contact point ciea:ances, narrow slots. and the like. These gages are made in many shapes and sizes (Fig. 59), and also with multiple b!ades (usually 2 to 26). Each blade js a speciEz number of thousandths of an in& thick. This enables the application of one tool to the measurement of a variety of thicknesses. Some thick- ness gage blades are straight. while others are bent at 4.5. and Wdegree angles at the end. Thickness gages can ah be grouped so that thrve are several short and several long blades together. Before using a feeler gage; remove any foreign matter from the blades. You cannot get a corrr:: measurement unless the blades are clean.

When using a feeler gage consisting of a number of blades, insert various blades or combinations of blades between two surfaces until a snug fit is ob- tained. Tire thickness of the individual blade or the total thickness of u/l the blades used is the measure- ment between the surfaces.

Care of Thickness Gclges

Handle the blades with care at all times. Keep from forcing the blades into openings that are too small for them. Some blades are very thin and can be bent or kinked easily. Blade edges and polished surfaces are also easy to damage. When not using a thickness gage, keep it closed.

Thread Gage

Thread gages (screw-pitch gages ) are wed to de- termine the pitch and number of threads per inch of threaded fasteners (Fig. 170). They consist of thin leaves whose edges are toothed to correspond to standard thread sections.

To measure the unknown pitch of a thread, com- pare it with the standards of the SCI~W pitch gage. Hold a gage leaf to the thread being measured (Fig. 61), substituting various sizes until you find an exact fit. Look at the fit toward a source of light for best results.

The number of threads per inch is indicated b!; the numerical value on the blade which is found to fit the unknown threads. Using this value as a basis, correct sizes of nuts, bolts, tap cutters, and die cutters are selected for use.

Fiqre i9. Thidmess gage. Figure 60. Screw pitch gage,

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Figure 62. using a WE gage to measure wire and sheet metal.

Wire Gage

The wire gage shown in Fig. 62 is used for mea- suring the diameters of wires or the thickness of sheet metal. This gage is circular in shape with cutouts in the outer perimeter. Each cutout gages a different size from No. 0 to No. 36. Examination of the gage will show that the larger the gage smaiier the diameter or thickness.

r.umber, the

Gages similar to the one shown in Fig. 62 are available for measuring a varietv of wires and sheet metals. The names of some common standard wire gages and their uses are given in the column head- ings of Table 4. The hody of this table contains gage numbers and their corresponding equivalents in dec- imal fractions of an inch.



Wire diameters may also be expressed in mils as well as by gage numbers. One mil equals one thousandth of an inch. Each decimal equivalent in the table can be converted to mils by multiplying by 1,000. For example, the circled decimal in the table is equivalent to .0640 x 1000 or 64 roils.

To use Table 4, select from the gages listed in the table the one that applies to the sheet of metal or wire you want to gage. For instance, column 2 states that the American or Brown & Sharp” Wire Gage shown in Fig. 62 is the one to use for nonferrous sheet or wire. Ncte that each of the gages has its own decimal equivalent for a particular gage num- ber.

To measure wire size, apply the gage to the wire as shown in Fig. 62. Do not force the wire into the slot. Find the slot that refuses to pass the wire with- out forcing. Then, try the next larger slot until one is found that passes the wire. This is the correct size.

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senwmber, your measurements are taken at the slot portion of the cutout rather than the inner portion of the gage. Now that you have the gage number turn vow gage over and read the decimal equivalent for ihat number.

To mrnsure the gage of a piece of metal, first re- move any brur from the place where you intend to apply the $age, Theu select the appropriate gage for the metal to be measured.

.&fter thr right gage has been selected, apply the gage to the wire, or to the edge of the sheet, as shown in Fig. 62. The number cpposite the slot tb,at fits t!ie c-ire or sheet is its gage number. The decimal eq:.~ivalcnt is stamped on the opposite face of the i’nqr.

need. Loosen the knurled nut at the end of the ban- die. and telescope the adjustable end of the gage to a size slightly smaller than the hole and retighten the nut. Insert the gage into the hole, as shown in Fig. 64. loosen the nut to permit the spring-loaded adjustable end to expand to the hole diameter, and tighten the nut. The spring-loaded contact of the adjustable end will assure proper contact. Make sure that the gage is he!d with the telescoping end at right angles to the axis of the hole to measure the true, maximum diameter. Remove the gage and measure the setting with an outside micrometer caliper.

Pel@scoping Gage

?‘,,/ix.tl;,ilrg gages arc used for measuring the in- s;&, size of slots or holes ap to six inches in width (ir &trnrtcx Thev are T-&aped ioois in which the shaft of the T is used as a handle, and the crossarm used ix measuring (Fig. 63). The crossarms tele- scope into each other and are held out by a light sping. To me the gage the arms are compressed, placed in the hole to he measured, and allowed to expand. .i twist of the locknut on top of the handle Iocks the arms. The too! may then be withdrawn and the distance across the arms measured.

These tools are commonly furnished in sets, the smallest gage for measuring the distances from 5/16 to l/2 inch, and the largest for distances from 3 l/2 to 6 inches.

To measure the diameter of a hole from l/2 :a 6 in. in diameter. se!ect from a set of telescoping gages the one whose range includes the size you

Figure 63. !mall h,:.; xd telescoping gages.

Small Hole Gage

F,,r measuring smaller slots or holes than the tele- scoping gages will measure, small hole gages can be used. These gages come in sets of four or more and will measure distances of approximately l/8 to l/2 inch.

The smuEi hole gage (Fig. 63) consists of a small, split, ball-shaped member mounted on the end of a handle. The ball is expanded by turning a knurled knob on the handle until the proper feel is obtained (the slight drag of the ball end on the sides of the hole). The gage is then withdrawn (Fig. 65) and the size of the ball-shaped member on the end of the gage can be measured with an outside micrometer caliper. On some types of small hole gages, the ball is flattened at the bottom near the centerline to per- mit use in shallow holes and recesses.

Figure 64. Using telexoping gage.

Figure 65. Measrxring &meter of a hole with a small hole gage.

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ding Gages

A marking gage is used to mark off guidelines par- allel to an edge, end, or surface of a piece of wood or metal. It has a sharp spur or pin that does the marking.

Marking gages (Fig. 66) are made of wood or steel. They consist of a graduated beam about eight inches long OR which a head slides. The head can be fastened at any point on the beam by means of a thumbscrew. The thumbscrew presses a brass shoe tightly against the beam and locks it firmly in po- sition. The steel pin or spur that does the marking projects from the beam about i/16 inch.

To draw a line parallel to an edge with a marking gage, first determine the distance the line must be from the edge of the stock. Adjust the marking gage by setting the head the desired distance from the spur. Ait‘hough the ba: of a marking gage is grad- ~lted in inches, the spur may work loose or bend. if this occurs, accurate measurement should be made with a rnle between the head and spur (A, Fig. 67). ‘So draw a line after setting the gage, grasp the head of the gage with the palm and fingers, as shown in B, Fig. 67; then extend the thumb along the beam toward the spur. Press the head firmly against the edge of the work to be marked, and with a wrist motion tip the gage forward until the spur touches the work. Push the gage along the edge to mark the work, keeping the head firmly against the edge of the work.


Dioiders are useful instruments for transferring measurements and are frequently used in scribing arcs and circles in layout work.

Figure 68. Marking gages.

To lay out a circle with n divider, set the ;livider at the desired radius, using a rule as shown in Fig. 68. -Note that the 3-inch radius being set here is being taken at a central portion rather than at the end of the rule. This reduces the chance of error, as each point of the dividers can be set on a grad- Cation.

Place one leg of the divider at the center of the proposed circle, lean the tool in the direction it will be rotated, and rotate it by rolling the knurled handle between your thumb and index finger (Fig. 69).

Vernier calipers, which have two center points similar to prick punchmarks, are partioularlv useful in setting a divider to exact dimensions. One center point will be found near the zero end of the scale on the rule. The other point is in line with the first and to the left of the zero on the vernier scale (Fig. 70).

Figure 68. Setting a divider to a desired radius.

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~;ig;~~? 70. Setting a di:id;:r xith a \-rmier caliper.

Set md secure the d?si:rd iettin~ on the vernier caliper and ad@ the divider mtil both points readilv enter Fhe center points on the vernier caliper, as sho\r-n in Fig. 70.

Plumb Bob

21 plmb Zloh is n pinred, tapered brass or bronze weighi \vbich is suspended from a cord for deter- mining the verfical or plumb line to or from a point on ihe ground. Com~uon weights for plumb bobs are 6. 8; 10; 12, 14, 16. 18, and 24 onnces.

A plumb bob is a precision inctrummt and must br cartd for as such. If the tip becomes bent, the cord from which the bob is swpendetl will not occupy the true plomb :ine over the point indicated by the ti;:. .: piiirnb bob usua!i2~ has a detachable tip 0 that if the tip should becom Damaged it can be

renewed without replacing rbe entire instrument. The cord from a plumb bob can be made mm

corrspicuous for observation p~xposes by attachrr?ent of a red-an&whiie iarget (Fig. 71).

Figure 71. Plumb bob, cord, and target.

The plumb bob is used in carpentry to determine true verticahty when erecting vertical uprights and corner posts of framework. Surveyors use it for trans- ferring and lining up points.

To locate a point which is exactly below a par- ticular point in space, secure the piumb bob string to the upper point, such as is shown in A, Fig. 72. When the plumb stops swinging, the point as in- dicated at B, Fig. 72 wili be exactly below A.

To plumb a strucFuraI member, or an electrical conduit, secure the plumb line A, Fig. 73 so that you can look at both the line and piece behind the line. Then, by si&ting, line up the member or conduit , - - with the plumb line.

Figure 72. LocatitM B point with a pilrmb bob.

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jiii:\,r(. 73. ~,umbin~ a struciurn, member with a plumb bob.

If this cannot be done, it may be necessary to se- ewe the plumb line at some point, such as showa at B, and then measure the oEset f;om the line to the piece at two places so that, for example, C and D in Fig. 73 are equal. If the distances between C and D are not equaI, adjust the structural member or conduit until they are.

Leo& are tools designed to prove whether a plane or surface is true horizontal or true vertical. Some precisioli levels are calibrated so that they will in- d:ate in degrees, minutes, and secorlds the angle in.&Fdion of a surfacl: in re!ation to B horizontal or vertical surface.

Se ied is a simple instrument consisting of B liquid, s~vch as &oh=1 OS J-I --r . rluO1vr~i?n, pariialiy filling & p&s vial “,

~9 -r tube so that a bubble remains. The

tube is nlounisd m a frame which nay be :Aminum, word. or iron. Levels ax equipped with one, two, or more tubes. One tube is built in the frame at right angles to another (Fig. 74). The tube shown in Fig. 74 is slightly curved, causing the bubble to seek always the highe>t point in the tube. On the cmkid~ of the tube are two sets of gradllotion lines separated by a spxe. Leveling is accompiished when the riir bobble is centered between the graduation lines.

To level a piece of er,uiprr?ent; owh as the work- bench shown in Fig. 75. with a carpenter-‘s level, set the level on the bench tn~ pwa?let to the Eront edge of the bench. No& that the ieve: has several pairs

Figure 74. Horizontai and vertical use of level

~igura 75. Leveling a bench.

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of glass vials. Regardless of the position of the level, nlwavs watch the bubble ifi the bottom vial of a horizontal pair. Shim or wedge up the end of the bench that will return that bubble to the center of its vial. Recheck the first position of the level before securing the shims or wedges.

To plumb a piece of equipment, such as the drill press {Fig. 76), place the ievel on the side and on the front of the main column of the press. Figure 76 shows the level on the side. Vse shims as necessary to bring the bubble in the lower via: of either pair of the hnrizontal via!s to the center in each case.

Lewis nest be checked for accuracy. This is read- !!*, ;~~mplirl~d bv placing the level 011 a true Iwriz~~t~t,~l slvfnce and noting the vial indication. Re- ~:c’IN~ tix l.~rl end for end. If the bubble appears on illll’ \idy III the gradilations with reference to the ~,p~.~tm m the first reading and on the other side for tlw M-WI~ reading, the level is out of true and must he dplSkd.

nr> i!oi drop or handle a level roughly. To prevent damrig?, store it in a rack or other suitable place when not in use.

Figure 76. Plumbing a piece of equipment xrith a level

59 I

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To& are the mechanic’s best friend. They are in- dis~ensnble servants, performing innumerable tasks lwwmd the power of vow own hands. Like friends, tw!s bcconx more v&able to you the better you :~r~’ .wrluaintrd witi) them. The term “bench work” ,‘Cil’l’lS Fl’.v: chipping, polishing, hand reaming, l~z!r~i t:l!@!g. :11l the many jobs done at the bench m i.r ix \-ise.

H~~gar&x of the type of job to be done, a worker should choose and use the correct tools in order to do the .tvork accu:ately, properly, and quickly. Metal- workin,g tools are carefully made and demand par- tic&r care if they are to work and last as the man- ufacturer intended.

Classes of Tools

The tools described in this book are classiEed as hand fools, measuring and layout tools, and hand power tools. Each type of tool has its special char- acteristics and purposes and should be used accord- ingly.

HAND TOOLS. Hand tools are usually small and are used with the hands to perform mechanical opera- ti0r.s.

MEASURING AND LAYOGT TOOLS. Measuring and layout tools are precision made tools used for mea- suri,ng and for laying out work accurately. (See Chap,

2.1 IIANJ POWER Too=. Hand power tools are operated

entirely or partly by power, such as elvtricity and compressed air, in order to make an operation easier or faster, or InOre accwate.

Hammers and Mallets

Types of hammers used in the sheet-metal shop are the machinist’s or ball-pea, the cross-pew, the timw’s riveting, the tinner’s peening, the setting,

the raising, the soft-face, and the brass-head (Figs. 1 and 2).

The essentiai parts of a machinist’s or ball-pee” hammer, thr all-purpose hammer used in working metal, are shown in Fig. 1. This hammer is used for bending and forming sheet metal and brass strip.

When it is desirable to leave no marks on the metal being formed, the soft-face or the brass-head hammer is used (Fig. 1) There are several varieties of soft- face hammers, some of which are made with a plastic head, while others are equipped with a renewable face of either rawhide or lead inserted in a steel head.

The cross-pee” or tinner’s riveting hammer is used to flatten tinner’s rivets on furnace pipes, ducts, and similar material (Fig. 1).

The square, flat face of the setting hammer (Fig. 2) is used for setting or Gattening meta! seams with- out marking or damaging the material. The single tapered peen on this hammer has a beveled end and is used for peening.

The raising hammer shown in Fig. 2 is used for raising doors and cornice ornaments and for other raising and bumping work.

Mallets made either of all wad or with rawhide faces are generally used on light gauge materials to prevent marring or damaging the metal (Fig. 2).

When a large number of sheets of heavy-gauge metal are to he bent or shaped at angles, machines tailed brakes are used. These machines are described in Chap. 4. Sheet metal up to 24 in. in width that is not too thick can be bent by hand.

How TO USE A METAL-WORKING HAMMER. In banding metal, only the face of the ball-peen ham- mer or mallet is used. To bend a piece of sheet metal, get two straight strips of hardwood, measur- ing approximately 1 in. thick by 3 in. wide and slightly longer than the width of the sheet metal, and a third strip of hardwood of the same length


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Figure 1. Figure 2.

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i-i\~ei;, i~ncl for driving the- rivet set and the lw:ldw. .+ ri\ vt wt icily hrndtl- is m<w,l!- a slro;-t pirce of tlw& vix~r! niid truqxwd twi stwt xrith a hole in we iwl xx1 :t conica! depression alongside the hole (Fig. 5). The lwle is used to force the metal pieces down on the riwt :;b:mk before tiw end of the rivet is Het- tencd The conical deprczsiou is then set over the ric-et errd with the header held in a vertical position, 2nd the header is struck with the hammer to shape the rivet after it has been flattened. For detailed in-




formation on rivets and riveting, see Chap. 7. Ma-

chinist’s hammers of various sizes or weights are used in riveting, depending on the type and size of the rivets.

RWLA~INT. BNOKEX EIAMMM HANDLES. Machine- made hickory handles in \wim~s sizes can be secured at most hardware stores. The portion of the broken handle that remains in the hammer head must be removed. The simplest and most effective method of doing this is to drill through it with a twist drill to remove as much wood as possible. It is then easy to split out several small pieces and thus remove the old wedged-in handle.

The end of a new handle is usually larger that re- quired and must be scraped or pared slightly before it will fit into the head o< the hammer. However, do not pare it too much, since it must fit very tightly. Aiter the small fitted end of the handle is inserted


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Comn~m Screc~driacr. The vnl-ions parts of R com- mm screwdriver are shown in Fig. 8.

Ratchei and Spiral Rntchct Scmcdriccrs. The two variations of the cominor~ sci-ewdriwr are the ratchet

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Figure 9.

;a;~1 ttlt, \p!~~al ratchet tb-p?s (Fig. 9). Similar in op- ~~.r~;~tic:rt to the common screwdriver. the ratchet type &ii 5”. scrIIu’- a in much faster and works semiauto- ini:tic~3tlv Riade5 of x-arious sizes can be secured for both tyiws of ratchet screwdl-ivrr, and both types tail be set for driving screws in or extracting them. Thr handtr of the ratchet scrrwdri,-er turns back and forth in the direction set.

Thrr spiral ratchet screwdl-iver operates even faster tbarl the ratchet. it can be srt for either in or out. To drive the screw, set the blade in the screw slot and push un the handle. steadying the blade with the qther hand. The blade makes several turns for each prt1.

Offset Smwdricer. Offset screwdrivers are de- signed for driving screws where there is insufficient space to use the conventional type of screwdriver (Fig. IO’!. The &set screwdriver is made from a piece of either round or ocvagonal steel with two blades at opposite ends at right angles to one an-


other and to thr shaft. When screws haw tn he driven in or extracted in inaccessible places. it is sometimes necessary to use both ends of the offset screwdriver, turning the screw a short distance with one end and then with the other.

Phillips Screwdritzr. The Phillips screwdriver is used only for driving the Phillips screw (Fig. 11). Philiips screws have a head with two V-slots which cross at the center. The tip of the Phillips screw driver blade is shaped like a point& or beveled cross to fit into these slots. To keep the blade in the cross slots of the screw, snore downward pressure is used.

Figure 11.

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</’ .I F-5 --

./ -- I~~~- _-



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To drill holes in sheet metal, either the hnnd or breast drill shown in Figs. 1G and 17 is used with 3 twist drill of the required type and sire. The chuck of the had drill (Fig. 16) has a drill size capacity of up to ‘i in. Whrre a larger size twist drill up to 1 in. mnsimum is rrquired, the breast dri!! must be used (Fig. 1-T)


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rE for clearawe. and when the cutting edger become duli. ordy thrw faces has-r to be ground.

The floti~ ;,I the twist drill is milled at an angle of abo;lt 20 tu 2i degrees with the axis to give the drill the n~ctxsarv rakt:. or clrar-anc~. txtween the cutting r,dgi, and ttr;, work (Fig. Iii 1. \‘lhvo this cutting edge is propcrl~~~ gmund. !t has n relief angle of about 10 to 12 deglres on the end: consequently the cutting angle of it twist driii noges usually from 55 to 60 degrees. The flute in a twist drill is designed so that the chips work out rasi!y while cutting. This is an ndded G;-antage when drilling a fairly deep bole. ?‘l,ev ?lji> ii’;\:? as leads for Itibricznts.

__I t IULK~- !S shows that, after the flute in the twist

:ilcl! tu$ i>rc,ri cut. the remaining portion of the sur- ‘~:tv:. ui the, 11ody of the dri!l is relieved, or cut away, .;x!d .t ILU smv Innd, or bxlv clearax~~. remains. This ii.iliii~i’S :iw ii-ictim I of the &ill in the holr. The tiri!:rtr,r~ scvtictn uf tlw bode of the drill. htturer~ the I,:: !~t:!:rii Ill illi. ililtrs, is c&d the xch.

iY,‘i!c~i ~JI.,I~CY Iv shurpenrd. the cuttir-i edges of a

,P* /

i NT


twist drii; produce a hole that is fairly round. stl-sight, and of the same diameter as the drill. How ever, a twist drill is considered essentially a rou@ing tool. Holes are made more accllrate by subscq~rrnt I-earning or grinding.

Syuure-shrank Twist Drill. Thr squni-e-shunk twist drill is designed to fit ixto tht chuck of a wood- working ratchet brwx (A, Fig. 19). It is made of meta! that has been tempered for use in soft metal. A wood-working brace is not ideal for dribGIg a twist drill al>d sholrld be used only if a hand or breast drill is not available, or when hidden nails or other unexpected metal may be encountered in the work. Sq-uare-shank drills are available in diameters rarlg- ing from 11,~ in. to z:i in. in gradations of I/~:! in.

Stmi&-shank Twist IX& Straight-shar& tT.:?st drills up to 1~1 in. ill diameter are used in rither hand or breast dnlls, smnll power drills, and the lightrl type of drill pwsses fitted with rither n two-jaw 01 a thl-re-jaw chuck.

There are two types of straight-shxnk twist drills: those with a neck or ring-shnprd groove in the shank, and those without a neck ( H and D, Fig. 19 j. The small sizes, up to ii in. in diameter, have no neck, and are inserted in the small hand and brvast drills by turning the sleeve outside the chuck to open the jaws wide enough, and then tighteniw in the opposite direction. Chucks used for drills la:-;;er than “4 in. in diameter are usually opened and closed by means of a wrench called a key.

Taper-shank Twid Drills. Taper-shank twist drills of more than I,/? in. diameter are used only in power drills. Hand dri!ls or breast drills do not have suf- ficient power to drive larger sizes &icier+ The small end of a taper-shank drill is machined &it to form a tang which fits into a slot in the end of the spindle socket in a power drill press (C, Fig. 19).

CLASSIFICATION OF TWIST DRILLS. All types of Morse twist drills are made of either carbon-i: ’ sterl or high-speed steel, Carbon-to&tee1 drills art Itsed in hand am breast drills and where lo->.r-speed driiling is requirr 7 vn power drill presses. T&y xc 1~s cr;~ens~,.~ ,~:, 1 ::.gh-speed-steel &ills.

High-speed-s, : drills are used ov high-spw:. power driven drill presses. They can be operated at much hiSher cutting sr.wd:. and will retain their cut- ting ed:;v longer than carbon-tool-stw! drills,

The E; of ?lorse twist drills are arranged ihi ‘O~LI group!:: mnnerical, alphabetical, fractional or ma- chinisi s, and metric. The mrmericnl sizes are “GRI- bered from ; to 80; ranging in diameter from 0.0135 in. to 0.228 in. ‘The number is stamped on the shank

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the chck i Fig. 22 j. The shali, is softa the,, the fluted part of thr drill_ md the j;iws of the chuck


Figure 22.

Hefore drilling a bole, check the drill :o find out grl,’ It more tic$tly. which iesscns the danger of

braking the drill. if it is gippcd tightly ial the chuck alid if it runs

1) 0 riot insert the entire length of the shank in the ciruck (I+‘$. 22 j, but leave a par-

straight arxl true (Fig. 22). Whelr a drill runs out of

tim of it cuatside to take up sconce of the strain. If true. a bent shank pwbably is respomible. .4 drill wobbles if there is a burr on the shmk. 411 wit-of-

tiw shmk is set in ail the way up to the fluted 1’0~. true drill will not bore B hole to the exact size re- timi the drill may snap. @red and is liable to break.

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Hacksaws and Blades

The essential parts of R hacksaw are the blade a,ld tbr adjnstable framr that holds the blade. An ef- ficient hacksaw is eqzuipped with a frame adjustable fnr 8 in._ 10 in.l nr 12 in blades; and has either a pis- tol-grip or a str-aisbt handle (Fig. 2;).

Hacksaws can be used tc cut practically all types of metals. with the exception of tempt-rrd steel.

To awe:-tai.-. whether n metal can he cut wit!1 n hacksa-.v. test it v,+th n file. If the metal cannot i,e filed. it cannot be cut with a backsaw.

IZSFRT~KG A H.I.CKS.~YJ Br.wr. To insert the blade iii the frame of the saw, first adjust the frame to fit



Figure 23

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L!vD HIADI:‘S 75

C!srw: A IIKKS.4\~. To prevent the blade frwn tw;dciy md tu :~ssur~~ n good clc;m cut, the material rnrrst he, stu~rc~lv f:wtelled in a vise (Figs. 26 and 07;1. .\IW~IVE st&t th;, cut at n slight ;qle, guiding thr blade ‘witb the tlrrunb of the left hand wtil the cut, or kerf. is of sufRcient de,>tb so that both hands c:IIl he usrd 011 the fr;une of the saw.

Wile12 starting the cut, it is not necessary to lift the hlnde off the work IX, the return stroke. After thr cut 1~1~1s bwn started, grasp the frame of the hacksau with both hands. one hand on the hxndle and the other hnud m the far end of the frame i Fis. 26 j. BiTalisi the hBCkSilM’ cr1ts only on the fOl.\Vi~l.d stroke. we a little pressure OWL the fwward stroke, but on tbr return stroke, lift the saw slightly 5; that the terth warccty touch thr mct;d work (Fig. 26). All strokes must bts long and ste;ldy SO th;tt ~wx-ly ai1 the i&h on the blade arc in USC (Fig. 27).

The amount of lxesrure used on the forward stroke is governed by the type of material ~1.1s the expe- rience uf the mechanic. Light pressure is u.vd on soft metals and on thin sections of ,nrtals, btlt more pres- sure js ~recessary on the harder metals and heaviel sections.

I& not saw too rapidly. A rate of apprcximately 60 strokes per minute should be the top speed. Slow. steady strokes with the proper pressure are far mo~-e effect;\~r than fast, uneven cutting. Always keep the blade of the saw moving in a straight line and use srlfficient pressure to keep the biade from becoming either jammed 01 pinched, since this tends to break the teeth or the blade.

BLADE BHEAKACE, CAUWY AND PREVENTION. If you examine a new hacksaw blade, you will see that the teeth are set, that is, alternately pushed out in oppo- site directions from the hlade. similar to the teeth of a wood-working saw. This makes the slot, or kerf, cut by the teeth slightly larger or wider than the blade. and thus provides the clearance necessary to prevent the blade from sticking in the material.

With constant use, the points of the teeth wear dwtr and btwme dull, and at the same time straighten or~t so that the kerf becomes narrows*. Thus, a dull bl:& has ii tendency to stick consider- :+ more than a IKW one, and forcing it through a cut will C:IIIS~~ t!w bMo to break.

If a b:xlr brrnks while a cllt is being made and :r I,C\V bl;ldc is ,~<xcss~~rv to continw tbc work, al- wik~~s start the new cut it, line with the first one, if p<wsit,lt,. If tbc piece of work is Roland or square. it

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I l.~cks~~~r blndt~ \vill also snap or break for the tc,llr,\\.illy w~sons: There mav not be enough tension 01, ii,? hi;1de (Fig. %,, or there mav be too much t:,lz<imr i Fig. 2%;; CT the teeth on ;he blade 17~~ ti:t\ t. hrrn too coarse for the material being cot. .I WK bladr may have been started incorrectiy in a kd cut h\~ a,, old blade. Too much presswe ma), iu\t’ been used m a blade. The frame of the saw may l.a~~e been twisted while sawing.

If a blade twists (Fig. :30) or bends slightly before it snaps. not enough twsion was put on the blade wheu it wa inserted i!r the frame. The tension mu::: bc i~~~wustd whrn a new blade is ixel-ted. If the blndr broke at the holes. too much tension was lxlt on it when it v-as iaserted. If a hrrakage is caused bv using a IKW blade in a kel-f started by an old hi&. the \r-ark must be ttmed around, and a new ci,t started to inert the old one. \\‘hen a break occurs because the material is too bard. a finer blade must he srktrd. If too much pressure on the blade causes a break. do not bear down se hard with a new blade. -\ hrrak caused h!T twisting the frame of the saw can be ~vnided bv pushing the saw steadily hack and fmtb in a straight line SC) that thrre is no wobbling 01 In-isting.

Rreakino or t\visting of the saw teeth may be cmsed b!; too much downward pressure when crrt- ting. Swnrtirnrs breaking or stripping of the teeth is cauwd bv starting the cut at the c~xm~~ of the ma- irriol. .&vays start a cut at a slight angle with the s&ice, not at the coiner, and keep off all sharp COT- *c-m





Fipwe 31

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Figure ,x.3.

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Ficwe 37.


__L Figure 38.


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CCP.!S /NAT / Ob! ‘WREbdCi-i




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Fio,,rr 47.


mavnblr, and a nut for adjusting the opening be- twren them ( Fig. 42). The pipe wwnch is the only tvpr USPd “1~1 ruurrd dejects. WC h zs pipes ;III~ shaft- ing, and it works in one diwction 011ly.

.A pipe wrench lnust ~wv(‘r be used on 3 nut or a bolthrad unless the corners have been rounded so that they cannot be turned with any other type of wrench. A pipe wrench will chew a nut or bolt so that it can never be used again. Because of the grip- ping action of a pipe or Stillson wrench, it is neces- sary to apply the force to the back of the IrandIe of the wreirch.

SOCKET WRENCHES. Socket wrenches comr in sets or kits (Fig, 43). These kits consists of several handles and a number of high-strength alloy steel sockets, which fit nuts of different sizes. There are two openings in every socket: one is a sq~ure hole to fit the handle, and the other a circular hole with twelve notches that slip over a hexagonal nut or the head of a bolt. Socket wrenches are used extensivrly in automobile repairs.

ALLEN WRENCHES. Allen wrenches are L-shaped bars of hexagonal tool steel (Fig, 44). They are spe- cially designed to fit the hexagonal sockets in Allen headless setscrews, which are used to fasten pulleys or collars in place on the moving parts of revolving machine shafts and other places where screws or bolts with protruding heads cannot be used. Two other L-shaped screw wrenches al-e made of round



Figure 44

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Figure 4.5.

twl steel with little flutes or splines to fit into othrt typ of h~dle~ setscl~ews. ht the Ails SCY~W ,,l,d \vrrnc!i are used more cxtensivelv.

Thr short rild of the wren& is inserted in the hcnd uf the .Allev srtscrrw when the screw is to be tighterwd or taken out. After loosening the screw

Coid Chisels

Cold chisels are forged from bars of silicxn-man- ganese aiioy steel, tough high-carbon steel, and sim- ilar alloys. They are made stubby and blnnt to give thrm greater strength. The cutting edge of a cold chisel is ground to nn included angle of about 60 degrees, then hardened and tempered.

In the sheet metal shop, cold chisels are used to cut or split the metal to required sizes aud shapes, to cut rods and bars to desired sizes, to cut rivet- heads. and to split obstinate nuts that cannot be nrowd with a wrench.

Cold chisels arr available in sizes ranging from :H in. to 1 in. The size indicates the width of the cutting edge.

Thc~ two types of cold chisels most commonly used in shert metal work are the Rat and cape chisels.

FLAT CHISELS. The Rat cold chisel is the type most commonly used. The Rat chisel has a slightl! rormded cutting edge, formed by R double bevel. It is used for cutting heavy gauge sheet metal or fol chipping a considerable amount of m&11 from huge surfacrs that cannot be filed or surface-machined (Fig. 43).

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CAPS CHISELS. The cutting edge of a cape chisel has a double bevel similar to that of a flat chisel, but is narrower for cutting narrow grooves and square cornws (Fig. 45). However, it is slightly wider than the shank, so that there will be no binding in narrow grooves. Cape chisels range from $6 in. to y2 in. in width.

Cutting with a Cold Chisel. A machinist’s hammer is always used to drive a cold chisel. The size of the chisel determines the size of the hammer. The co!d chisel is always held loosely between the thumb and the first finger of the left hand (Fig. 46). The re- maining fingers must hold the shank of the tool loosely. With the hammer in the right hand. strike sharp. quick blows with the flat face of the hammer and gradually increase the force of the blows as the work progresses.

Crltfing Sheet Metal Held in, a Vise. Before plac- ing sheet metal in a vise to be cut, mark the metal with a scriber to indicate the cutting line; then, using the scriber or a sharp-pointed tool, deepen the he. Clamp the sheet in the vise -bow the jaws so that the scribed line is just visible and parallel to the top edge of the vise.

Hold the chisel at an angle to the sheet metal 50 that the cutting edge shears it across the top of the vise jaw. Strike sharp, quick blows with the Rat face of the hammer, and drive the chisel forward along the line to be cut. Always start a cut at the right- hand edge of the metal, and drive the chisel to the left and toward the solid stationary jaw of the vise (Fig. 46).

Cutting Sheet Metal on a Metal Block or Anvil. To cut sheet mctr.! on a block or anvil, first mark and deepen the cutting line on the meta! with a scriber. To get a clean-cut edge, always lay the sheet on a block or anvil of soft iron or soft steel. Never use n wood h!ock. The m&d block must he placed di- rectlv under the point where the cut is to be made.

II&d the chisel vertically to the surface of the sheet (Fig. 47). On plate or heavy sheet metal, the cut deepens gradually, and if is necessary to go over the line several times before it is cut through. On thin sheet metal, the cut is made almost imme- diatrlv (Figs. 47 and 48).

To ‘cut along a curved line, a chisel of narrow width must he used so that the shape of the cut will wnform more closely to the curved line.

Cutting Hods or SmuIZ Bars. To cut a rod or a small bar, mark the metal to indicate the cutting point. Lay the rod or bar on a block of steel or iron (Fig. 47). Hold a flat cold chisel in vertical position

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Fipre .52. Remaaing frozen nut and Loosening rusted threads.

or studs may be collapsed with a puxb or round nose cold cbisei 7 Fig. 51:)

To remove a frozen or rusted nut or one with rounded cornersi apply some kerosene or thin oil and allow sufficient t& for it to wurk into the tbrelds. Then, with a sharp flat cold chisel, split the nxt acd remove it (Fly. 52).

.Slulrpvtling C&l 6hirls. The cutting edges of carbowsteel &~ld chisels are kept in good condition hv @~Iir;g them on a dry emery wheel or a iYet g~in’~stone. Cold chisels made of cbromiom vana- dium steel or a similar alloy. tbci:gb extremely tough, art: soft enough to be filed rather than ground. This

eliminates the danger of burning the edges of the tool.

Flat cold chisels should be ground so that thry have a slightly ccnwex edge (A, Fig. 53). Chisels to be used on hard or tough metal should be ground to LX” included angle of approximately 70 degrees. For use on softer metals, they can be ground to angles ranging from 40 to 60 degrees, depending 011 the metal ( B1 C, Fig. 53). Recommended angles are 60 degrees for cast iron; 50 degrees fJr wrought iron. bronze, doralumin, and manganese; and 40 degwes for aluminum, aiuminum alloys, copper, zinc, and brass. A small sheet-metal template, or pattern, cau easily be made for checking and maintaining the angle of the cutting edge that is being filed 01 ground (Fig. 53).

If a dry emery wheel is used, the chisel should he held against it with very little pressure. and the cot- ting edge should he dipped into cold water fre- quently to retain its temper. When a wet grindin!: wheel is used, dipping is not necessary.

The incessant hammer blows on the end of the handle of a cold chisel eventually upset or muslr- room it, and this will cause splinters to fly when the chisel is being hammered. It is very dangerous to use a cold chisel in this condition. To prevent pos- sible splinters, grind off all the spread-out m&al SO that the end is Rat and set siightiy tapering (A. B. C, Fig. 53).

Roofing and Gutter To.?gs. Seamers and Beaders

TZWS. Roofing and gutter tongs are wed for turn- ing up the edges of sheet metal preparatory to the foxzing of stxx!ir.g seirirrs “i :oiks. Th;- Vhr iuua types of roofing and gutter tongs in general use are shown ir, Fig. 54. T!E conventional roofing tongs shown at A, Fig. 54 can be used to turn only a speci- fied size seam or lock. They are available. in sizes ranging from ‘/z in. to 2 in., and in gradations of I$ in.

The clamp tongs shown at 6, Fig. 54 have a jaw depth of 3 in. This type has tile advantage of heing equipprd with a special clamp.

A type of guttei. tong in general use is shown at C, Fig. 54. This type has a jaw depth of 14 in.

“Reese’s” patent tongs, shown at D, Fig. 54, are adjustable and can he used to turn any required size of seam or lock ranging from :ji in. to 3 in. in depth.

“Stow’s” improved tongs, shown at E, Fig. 54, arc adjrlstable. They can only he adjusted to turn five

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Figure 55. “Burritt’s” patent double seamed.

widths or depths of locks or seams ranging from ?,$ in. to 1 I,, in. in ?i in. gradations.

The deep threat roofing tongs shown at F, Fig. 54 :~re w;;iipped with an adjustable gauge and can be llsed for turning edges from ?$ in. to IO?4 in. in 5j in. gradations.


Figure, 56.

SEAMERS. After turning the edges of the roofing with the roofing tongs, a tool called a double seamer is used. The “Burritt’s” patent double seamer is a type grnzrally used for this purpose (Fig. 55 j. This type of seamer, used to form a double seam in stand- ing seam roofing, is further classified as a common- and wide-gauge seamer. The common-gauge type is used to follow and complete the seam made by the standard 1 in. and 15’1 in. roofng tongs. The wide- gauge roofing double seamers are used for the same purpose as the common-gauge type, but they will finish a standing seam I in. in height. The hand roof- ing double seamer shown in Fig. 56 is used for the same purpose as the type shown in Fig. 55. When using the hand roofing double seamers the seams are finished by hand with blows of a mallet against both sides of their flat surfaces.

GVITER BEADING TOOLS. Gutter beading tools or gutter beading machines, as they are ca%d, are used for forming a bead on the edge If gutter sheet metal (A, Fig. S?). The two types generally used are the adjustable and plain header.

The adjustable beader shown at B, Fig. 57 forms beads in gutte:s up to 30 in. in length. The various- sized metal rods necessary for forming beads rang ing from z/8 in. to 76 in. can be inserted in this beader. The metal that is to be formed into a gutter bead is inserted into a slot that is milled in the form- ing rod. Using the hand crank, the shtwt metal is wound around the forming rod, thus completing the bead. The rod with the sheet of metal and the formed bead can easily be lifted out of the too: and the beadr-d work slipped from the forming rod. Tbis tool is adjustable and can be set so that it will form any number of brads of exactly the sanw size with- out additional ;Idjnstment.

The plain gutter beading machine shown at C, Fig.

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Tlw t\pr of uwt,d ti, br cut awl the g;u,ge of the rxt;d d~~trl-minr~ ihe comet uiz~ of \nipc to usr. \lild stwl requires a larger pair of snips than aluminum. and Ir;~rd brass rcquiws larger snips than soft brass. Tbrse snips and shexs. with the exception of the con-ilx~~~~~d Irvrr shrars, can be used to cut sheet md only up to 20 gauge. Compound lever shears of the tvpe sho\vr~ iri Fig. 80 can tx used to ixt q’ to 12 gauge. E~eav~-g;~~~ge metals must be cut with ei?her ii !iacksaw, a cold chisell or heavy power rqrripment.

Snips should never br used in place of pliers OT wire cutters. To avoid springing the bladrs. do not attempt to cut material of heavier gauge than that for which tlw snips are intcndcd. Snips ,that have been sprung are useless and cannot be repaired.

IIIXXJI.AR on S~LUCH~ SNIPS. Hrguiar or straight snips are used for cutting straight lines 01’ circlesvof large diameter (Fig. 60). Straight snips are avai%le for both right-handed and left-handed users.

Doun~~ CUTTING SNIPS. Double cutting snips have :L top blade with a double cutting edge into which the towm blade works (Fig. 60). They are used in the same manner 3s regular or straight snips, but principally for cutting light sheet-iron pipe, stacks. ard thin-gaugr cylindrl-s.

ciIir:rLm OR C:unvr:n S.vrE3. Circular snips have ~II:.LYY~ bl;~d,~s and are :Isrd fur cutting insidr scrolls or circles uf sn~all di;tmetcr (Fig. 60). To cllt a cir- CIIIRT opwlilly in a slfi<,r.t of rrrrtal, it is ~wcrssary fit-st to ~7~x11 ii II& on thv ileidr of the olltline of the (lr~+rt~i op(lnilig so tll;rt the blxles of ttrc snips ma) be staric.d.

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Figwe 61.

.~li?A,iKiN .sTm5. Aviation snips are designed and -g’il\iii~?i 1~~~~~ (& sprcifically for cutting heat-treated airiiniiiti in aihys an d stainless steel. The blades of these snips have smal! teeth on the cutting edges, and the handles are m+de t:, girr greater lever-age for heavy cutting. This tool usmlly cuts up to 0.050 in. stock (Fig. 61).

Correct Method of Using Snips and Shears. All types of snips and shears are med in approximately the same manner. If the material is light-gauge sheet metal; hand snips will be used. For 22 gauge or lighter mild stee!, use straight or combination snips. For 16 to 20 gauge mild steel, nse bulldog sr:ips. Al-

ways place the cutting edge of the upper blades ex- actly on a guideline mwkyd on the metal, and insert the sheet as fair back a5 possible hrtween the blades (Fig. 62). Hold the siiips .so that the flat sides of the blades are at all times prl-pendicular, or at right angles, to the surface of the work. The waste metal or the smaller piece should curl on the npper side of the lower blade.

All crltsl and especially curved cuts, must he con- tinuous. Complete every cut with the point of the snips to avoid cutting beyond the required point.

When it is necessary to cut a hole or an opening in sheet metal, !ap the metal on a bardwood block and punch a hole in it with a hollow punch or a small cold cbise!, so that the point of the snips can be inserted to start the cut.

The pivot point on snips must be oiled frequently, and the nut on the pivot must hc edjusted so that the handles are not too tight and can be moved with ease (Fig. 62).

An outside circle as well as a straight !ine can he cut with the combination snips. Cut off the corners of the metal to make it easier to handle. Then make a continuous cut, turning the metal as the cut is being made. If possible, remove the waste material in me piece. Use a hawk’s bill, aviation, or pivota snips to cut an inside circle. To start the cut, punch a hole in the center of the circle to be cut, work out to the line, and then follow the line around until the cut is completed. The pivotvr snip is one of the hand- iest hand cutting tmls; hecause it will cut irregular curves as well as straight lines.



~iqure 62. Cutting with snips ad shears,

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Rr.ow~~ns ST.WF / Fir:. 64 ), Both the short ta- pd horn at one end af this stake and the kmger hwn at the other end are wed for fwming, seaming, aml riveting fwmels. pitched covers, lids, and sim- jjar tsDerrd nhiwtc - -, _ _ .-

CZTDLFMOLD S-FAKI; Fig. 65). Th? two horns of differrnt tapers on ‘his stake are used for for&g, swminy. and lEx~.?irrs object, with t.it1x.r RariIlg lines or ends.

Figure Hi.

CREASING STAKE (Fig, 68). Two types of creasin% stakes are availahlc. The sever;11 pro&d slots in thr double rec!;lllgular-shaped horn of one of these types is used for brnding wire and creasing sheet metal. Thhe other type of creasing stake has a wctangulw- sh;ywi. hoi-n on one end and a round tapering one on the other end. This type is generally used fol fol-ming and riveting small I-ounded and tapered work.

Fipwr RR.

DOVBLF: SEAMING. STAKE (Fig. 69). The two ellip- tical-shaped horns with cnlargrd knobs at both ends

Figure 69.

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iif this stake are used for double ieaniing small cyliu- diiW1 wxk.

H.AKH~.-~ SI~AKE (Fig. 74). Tlw s1~1rp straight edge that is hcveled on one side of !his stake is used for hending edges, making sharp bends, a1~1 fork forrni~~g pans7 haws, and similar w.~~k.

C;O?.lhI;>NSQUAlW SrAKl; (E‘i!& 75). l‘h‘! fiat SqUkW head and long shank of this stake are used for gen- ad operations. *

&XI. EIXX ST.4KF (Fig. 7” 1. The d&t shank of this stake permits the work to cIeax the bench. ‘The fiat, squat+ head with bewird edges is used for

’ doubie srarnirlg qwatioos.

Fiqire 72.

TE.huiT?LE Sxhxs c, Fig. 7:). The four d&Tent- shaped intrrchangeable heads af this stake are used for many formirzg operations for which other stakes cannot be used.

Figw 74. Fil$m 75.

COPPERSMITH SAKE (Fig. 76). One side of the bead of this stake has a sharp rectangular edge and the other side a rounded edge. It i5 also a general purpose stale.

BOTTOM S.TAKL: (Fig. 77). The fan-shaped, slightly rounded. and beveled edge of this stake is used for tumirrg small flanges, for double seaming, and fat dressing burred edges on discs.

Fipmt 76 (uho~~)

Figure 77 (right).

HAND DOLLY STAKE (Fig. 78). The Rat face of this stake has two straight edges, one concave edge and one convex edge. It is available in various sizes and shapes. and is used for bucking rivets and double seaming.

Figure 78.

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Figure 83.

lar. circular, arid triangular (Fig. 8:). From these three classes hire deriwd all tht odd and irregular forms classified further as miscellaueous, which are subdisidcd into taper and blunt; again according to genera! co:~tcnr or ootlirx

Taper designates a file whose cross section grad- uall~z narrc~ws in width and thickness for one-hi;lf to tw&hirds of its length; blunt designates a file that keeps the same cross-section size throughout its length (Fig. 8.5).

Files are classified aIso according to the cut of teeth; as single-cut_ double-cut. rasp-cut, and curved;


Figure 84.

and according to the coarseness of the teeth, as rough. coarse, bastard, second-cut, smooth, and dead-smooth (Fig. 86).

Single-cut j&s are used generally with light pres- sure to produce a smooth surface finish or a keen edge on knives, shears, saw teeth, or other cutting tools (Fig. 86).

Double-cut files are used generally under heavy pressure for fast metal removal and where a rough finish is permissible (Fig. 86).

Kus[~:ri~ files have a series of individual teeth cut by a sharp and narrow punchlike cutting chisel. The rasp-cut file produces an extremely rough cut and is used principally on wood and leather, and on alumi- mm, lead, and similar soft metals, for fast removal of waste material (Fig. 86).

A speciul curoed-tooth single-cut file is used on the Rat surface of aluminum and steel sheets.

Rough, coarse, and bastard cuts of files are used on heavy work, and second-cut, smooth, and dead- smooth files are used for finishing or on more exact- ing work.

The teeth of a file are cut into its face at an angle. and sometimes they are cut into one or both edzes of a fat or rectangular file. When a file has no teeth on one edge, it is called a safe-edge.

FILIYG ALUMINUM. .bilrnninum is difficult to file with ordinary files because it is a soft, ductile, and malleable metal. The file teeth soon becomr clogged, even under moderate, even pressure. Filing of alumi- num consists of filing roughness from aiuminum cast- ings, filing sheet and bar aluminum, and filing aluminum alloys. For fast, rough metal removal, a special aluminum rasp is often used, but the alumi- num file (A, Fig. 87), a recent manufacturing de- velopment, cuts aluminum rapidly, yet leaws a good finish. Its special tooth construction is very effective in eliminating clogging (B, Fig. 87). Compare this with the regular flat file shown at A. The upcut of the teeth is deep with an open throat, and the overcot is fine, producing small scallops on the up- cut; which break up the filings, allow the file to clea- itself, and prevent taking too large a bite from the metal. Py using this file with a shearing stroke to-


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FII.IXC linass. Brxss has a structure al1 its own and is ii difficult metal lo file Th:mgh softrr than steel, imzj is both totI&!: and ductile. These charactrristics hwd 2 filr with terth that are sturdy. wry sharp, ;:lrd cut to air angle that pre\-t.ibts $rooring ad rxn- l~il~g the file off thr work. Still ~nwc importanti the 5112 nest not clog. in addition to a short upcut angle, the teeth of a brass fib like those of the alumit~rxn file. have a firie iuil~-;%ng:le ~~~~~~~~~ that e~dde~ the file to dear itsrlf of chips. This brass file is so de- signed that thr sharp hi$cut teeth bite deep into the metal with little pwssure, and their short upeut ;1iig1e prodllces a smoothing cfirct (C. Fig. 87).

~;ILIXC Sraraws S.TEEL. Thr tremendous increase ill the use of stainless steel and similar alloy steels has created a new and distinct filing prohI&. The hard chromium ad nickel c:mtrr:t IS these types of GW: makes them extremrlv tough, dense, and tliffi- rrllt to file. Ttwir abrasive &ion greatly shortens the life of a ~twr<*t-prlrpo\e fiie.

The s+cial stainless-stcrl file shown in Fig. 88 has overcome this prubi~m. It is a file of ex&ptiorral we;wing qualities. When properly .rwd, with a light pressure comhinxl with ii rhv steady stroke, this inew file removes metal rapidly, requiring but little dfort, and leaves a good finish. It is available in the same shapes and sizes 3s general-purpose files.


nL”M I NUbl TYPE -,A


Figure x7.


Figure 88.

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FiLES ASD FILING PROCEDI’RES 97 F,rr\-c LF:-III. Estra-soft metals. siicb 2s lead. hah-

hltt. ai;d pure copper, p i-erent filing conditions clilite distinct ii-uw the &en previoiisl~~ mrntioned. \letal rcrno;A. in ~~~rm~l fiiiy jobs oil extra-soft metals, is done on virtually 3 st*ai\,ii,g pl-illvipic. Fui- lr;ld, tbl, lend hat file shouw in Fig. 89 is used. Its coarse. shc;rt-angle, single-cut teeth zre really a series of stubby blades which shear axa!- the metal rapidly under ordinarv pressare. Li&t prcssurr with the


Fi&i:<. ss.

same fill, ]~~!!dilcrs a smootbirig cffrct. This file i> ,is<.d r\-tcllsi\,elv on I<7d pipe fittings, solder joiiit5. 211d similar work. It is used also on soft benrings. s!liil;s. illld ino]drd Invt;d ]Wts.

Sxlonrl~-l. Ixw*!x(: Son MI~:I~LS. FI,I- snu~oth-fill- istring soft ~rlrtnls: alloys, such as aluminum, brass, ax1 copper; and other materials, such as plastics; bard rubber; and wood. a special shear-tooth file has been designed (Fig. SC). This file combines fast re- moral of material with cxcellrnt smoothing qwlities. The coarse, long-angle, single-cut teeth help thr shear-tooth file to clrar itself of chips. thus minimiz- ing clogging. Its coi~~st~~~ess prorides fast cutting. while the long angle gives the sheaing cut which leaves n smooth finish.

Under certain conditions, as ou narrow surfaces. thr shear-tooth filr has a trndrncy ti, r,,n to thr left because of its long englc. To ovwco~~~~ this tcndww it should he used with a sc:ncwhat diagonal stroke to the right.

INELRTING A FILE IN A RANDIX It is extremely dangerous to ,,se a file wit!;out a handle. Woodrn hand!ts uf various sizes are avnilabie and al-e exile installed. Reforr inswting the tang of the file in the handle, make certain that the hole is !xge enough. <:rasp the handle and insert the tang into the hole so that the file is pointing rpard (Fig. 91). Holding it in this position, hit tbr bottix end of the handle ;igaiast the workbench or other sclid srlrface. This drives the file tang doww into the handle. Aithou~h the fcrrrrlr or mr:lal sleeve on the h:md!c should kw]> ttrf. vi~ood fl-om splitting, do not try to dri\,v ttw tarIS in too far. To rrmovc a file from the h;undle, bold


R)y” 91.

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.Ifter the surfaces of the parts to he joined Lwe bwn cleaned, thrv should be fitted and srcured in place. then coated ‘with a suitable flux (szc Table 16). After this, the application of the hot soldering copper and ihe proper amount of melted solder to the adjoining parts will cause them to adhere.

FLUXES. There are two classes of fuses: Corrosive and noncorrosive. The corrosive Hexes eat away thtz soldered metals unless they are thoroughly washed off after soldering. The flux: ordinarily used for soft

T.~LE ‘16

solderi~rg are solutions or pastes that contain zinc chloride. Zinc chloride and sal ammoniac are corro- sive fluxes.

Practically all clean metals when exposed to the atmosphere acquire a film of rust or tarnish, The thickness I;f this film increases a.? time goes on. Mois- ture and heat help speed it up. This film or oxide is preserlt even though it is invisible. it is difficult to get solder to adhere to such metal, because the solder must “wet” and penetrate into the pores of the metal to be soldered. A chemical material is used to pre- pare the metal for the wetting or alloying with molten solder. This chemical ti; called a soldering flux.

A soldering flux is used for the following purposes: first, it removes tarnish or met:dlic oxide; second. it prevents further oxide from faming while the metal is being heated to soldering teanperature; and third, it lowers the surface tension cf thr molten solder, enablir:g it to spread about the area and pen&rate where it should.

Although there are maoy COIY, mercially prepwxl fluxes available, sheet metal workers genen!!y prefel to prepare their own flux by “cutting” zinc in muri- atic acid (also known as MCI or hydrochloric acid). thus producing zinc chloride. This flux is also catted “cut” or “killed” acid. It is used as a flux when sol-

dc,l-ing &a~~ galvanizrd iron. zinc. L-d, copper, hi-ass. ;mti tin plate that has hew exposed to the weather.

1-c lwkc, zinc chloride flrw. proceed as follows: Drop piwes of zinc into a glass or earthenware jar containing mrlriatic acid until the acid stops boiling ;ud ln~bblw haw stopped rising to the surface. \Vheil all hoilills has stopped, the solution is strained. Note that zinc chloride must be prepared outdoors or IWW an nprn window and away from heat or RawLes of any kind. becarrse the fumes arr injul-iorls and inRan~nx&~ie. Zinc chloride, when not io actlla! IISC. mmlst be kept iu closed containers.

\Irlriatic acid is often wed in its raw or original state as a Hu.x for soldering g;d\anized iron and zinc.

Path raw and “cut” or “kitlc& acid fluxes are cor- rosi\~r and most he w.shed off when the soldering job is completed.

\YIMY! soldc~ring tin plate, hrizht copper, or pewter. rosin is used as :L flux. Rosin is the most commonh usrd non-corrosive Hux of this tylx, and it does not have to he washed off. It is awilable in either pnstr. podrr, m liquid form. Kosin does not clean thr rrrrfxe of the work, hut it does prevent oriclation duri:lg soldering hy covering the surface with a pro- tective film. Liql~id HIIX~S arr usually applied by a brush. The flus is spread lightly along the seam 01 joint that is to he soldn-rd as shown in Fig. 2. When either powdered or paste rosin flux is used, it is either spwxl. sprinkled, or melted on the work with a hot soldering copper.

I h



Figure 2.

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SOLDEE. Solders used by sheet metal workers are made of varying percentages of tin and lead. Solder should always he secured from a reliable source, be- cause a good soldering job is largely dependent on the quality of the solder being used.

Tin is a metal endowed with a few unique phys- ical and chemical properties, In the molten state, tin dissolves and alloys readily with many metals. A soldering flux, as previously explained, helps to do this.

It is this property of tin, coupled with its low melt- ir~g point (450 deg. F.), that creates the fusible alloy we call soft solder, or just solder.

If pure tin, which melts at 450 deg. F., and lead, \vhich liqxfies at 620 deg. F., are mixed in the pro- @ion of B3 parts of tin by weight to 37 parts of lead by weight, the surprising result will he a fusible alloy that will melt at a temperature even lower than the melting points of the two metals-361 deg. F. This is the lowest melting composition of tin-lead mixtures.

Tin mixes with lead in all proportions. The most common compositions are 40/60, SO/SO, and 60/40. Tin, contrary to popular belief, is an expensive metal. There are no tin mines in the ‘Jnited States; conse- quently, it must he imported from countries in Asia, Africa, and South America.

Lead, “11 the other hand, is a cheap metal, ordi- narily selling for about one-sixth the price of tin. Of course, the more tin in the solder, the more costly it will be.

A good solder is 40/60. It is an all-round solder and contains 40 per cent tin and 60 per cent lead (the first number mentioned is always tin). This solder starts to soften at 361 deg. F., goes through a mushy or plastic stage, and becomes camp!&+ liquid and mubile at 460 deg. F.

Some prefer 56/‘50 solder, also called “half and half.” It has a narrower plastic range, becoming com- pletely molten at 414 deg. F.

An excellent solder, the 60,/40 composition, is more expensive, very fluid, and is used where a low melt- ing solder is required; for example, on pewter ware. 60/40 is liquid at 370 deg. F.; its plastic range is very narrow, from 361 to 370 deg. F.

Solders of these varying percentages of tin and lead are available in bars weighing from $ to 1% lb. each, or in wire form ranging from ,009 in. to ,250 in. gauge or thickness.

SOLDERING C”PPERS (Fig. 1). Successful soldering requires enough heat to raise the area of the metals to be joined to a solder-melting temperature.

There are many ways of transmitting heat to a metal surface or joint. The most popular and pre- ferred method of transferring heat is by means of n soldering copper.

Not only does a soldering copper deliver heat to the metals to be soldered and melt the solder, hut it also enables the user to sweat seams, smooth ol;t the wrinkles in pasty solder, and make a neater appear- ing job.

Soldering irons are avaiiahle ip many weights or sizes. Gas or forge-heated soldering irons “r coppers, as they are often called, are sold singly, or by the pair, because sometimes it is desirable to have one of these irons heatiag up while the other is in use, to avoid interruption of the work.

A copper weighing s lb. is suitnhle for light work, a 1 lb. iron for medium weight soldering, and a ll,$ lb. iron for heavier soldering. Coppers may he pnr chased that weigh 4 and 5 lb. to the pair for even heavier work, See Chap. 3 for a description of the various types of soldering coppers used in the sheet metal shop.

It is not enough to have a high temperature cap;<- ble of melting solder, hut there must he also a great enough volume of heat transmitted by the iron to the work to raise quickly the temperature of the metals to he joined to solder-melting temperature.

Not only must a soldering iron he hot enough, but its faces must he smooth and well “tinned” (solder- coated), It is the tinning that provides for the quick transfer of heat into the metals to be joined and also enables the iron to glide along smoothly.

If the faces of the soldering iron tips are oxidized (black spots) or pitted so as to prevent the rapid Row of heat, they must he filed fla* and smooth, down to the bare bright copper, before tinning.

Filing and Tinning Coppers. To file the copper before tinning, proceed as follows:

Heat the copper to a cherry red and clamp it iri a %vise, Using a single cut bastard file, file all four sides of the c”pprr until they are bright end smooth (Fig. 5). With the copper held in the position shown in Fig, 4, round off all of the sharp CO~WS.

To tin the soldering copper, proceed as foliows: Reheat the copper just hot enough to melt the sol- der. After applying a little solder, rub the tip of the copper hack and forth on a cake of sal ammoniac until the tip is tinned or coated with a coat of the solder (Fig. 5).

After tinning, the copper is ready for use. Forging the SoMering Copper. It is sometimes

necessary to forge a soldering copper. Coppers are

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Fipr’: ?.

(.,lsil\ trrlC!~,d to tile required shape. on eithcl- an an- Cl or il rnrtal block, I,\- the following procedure: I ?i,i~t the copp to a dark ctwry red, clmmp it in ii vise in the position shown in Fig. 3. and fik off pit- mwks and 2oy dross, scale or othw imperfections that may be found on the copper (Fig. 6). Remove the coppev from the vise. I-&cat it; and place it as shown in Fig. 7. Witb a heavy machinist’s ham- mer. hammer the missh;~pwl $rt back into the bod\~ (Fig. 7). R~mow thr~ wppw from thr vise and reheat it. Hold the copper on an anvil il~on plate and forge to the required shape by striking solid


FiLy’” 4.


blows with the flat face of a heavy hammer as shown in Fig. 8, turning the copper frequently to forge a square surface. When forging a copper, reheat it as often as is found necessary.

Using a Dipping Solution. A dipping solution is used to keep the tinned part of the soldering copper bright and clean. This solution is made by dissolving 15 ounce of powdered sal ammoniac in a quart of clean water. The soldering copper is dipped into this



Fi~llP 6.

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Figure 7.

solr~tior~ irnrnediately after removing it from the Hame CT heat. When a dipping solution is not avail- zbie, the copper shwld be wiped lightly and quickly with a cntt!u rag, Never we a woolen rag for wip- ing, nrn auy solution other than snl ammoniac for dipping.

Soldering Procedures

SOLO~:~IX LAP SEAMS. To solder lap seams, pro- cecd as follows: Place the work on a suitable sup- port as slrowt~ in Fig. 9. .4 sheet of black sheet iron or a piece of glass or marble !/; ta 1 in. in thickness


is excellent for this purpose. Heat the tinned copper. Apply the flux as shown in Fig. 2. Dip the heated copper into the dipping solution and touch a bar of solder to the heated tip of the copper (Fig. IO). With the drops of solder that adhere to the copper, tack the seam at a number of points to hold the sheets in position while soldering. The method of holding the sheets in position is called tack welding and is shown at A, Fig. 11. A properly tacked seam is shown at B, Fig. 11.

After tacking, apply a hot, well-tinned soldering copper, with the point extending over the seam on the single thickness of the metal and the heel or back of the copper over the seam proper, at about a 45 degree angle. Touch a bar of solder to the hot cop- per while it is in this position. As the solder melts, draw the copper slowly along the work, keping it at an angle and allowing it to draw or sweat the solder the full width of the seam (Fig. 9). Make as long a stroke as possiblr before the soldering copper beco~nes too cold. r’/hen it will no longer melt the solder freely. change it for a hot one. Beginning at thr point where the soldrSng was stopped, hold the wwnd hot copper on thr seam long enough to remelt the solder at that point. then move it along just fast wwgh to make a smooth seam.

If an acid flux has been used, be sure to wash off all tracrs of the flux after soldering has been com- pled



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Fil:urr 10.

s~~.~~~w.Jc CROOVFU OR RIVETED SEAMS. Tacking is ,,ot ~~~rssary when soldering either grooved or riv- rtrd sc*ms. Wheu soldering these types of seam% apply the p~op~-r AIM and solder the seam in the same manmr as for the lap seams previously de- scribed. However. whell a water-tight job is required 011 a riveted seam, the x-iv&s must be soldered in ad- ditiw to the seam. as shown in Fig. 12.

SOL~E::KING VERTICAL SEAMS. To solder vertical or opright scans. such as are frequently encountered in roofing work and similar jobs, no matter what metal is to be soldered, the soldering copper must be forged to a wedge shape as shown at A, Fig. 13 and ;:b<xt ?! in. wide and ‘/ in. thick ai the point.

al!- thr end and top side of the copper ars tinned. The tinning area is indicated at B. Fig. 13. (Forging and tinning instructions are given previously in this chapter.) If all four sides of the copper are tinned. eonsidcrable solder will run to the underside end ;SW:S,Y fume the seam itself, resulting net only i:~ a waste of time and effort but also of material. Aftel tacking, solder the seam in the same manner as that described for other senms, with the exception that the handle must be held higha than the copper (Fig. 9 j to allow thr solder to flow until the news- wry anmmt of solder is on the seam and sweated into the joint. This is nccomplished by heating the co[~per thoroughly and movilrg it alter-nately to tht,


Figure 11.

right and left on the seam itself, thus drawing the solder into the seam as shown in the detail C, Fig. 13.

SOLDE~INC Borrohns OF CYLINDRICAL, SQUARE, AN!> REC~ANCULAR JOBS. To solder bottoms of cylindrical, square, and rectangular jobs, proceed as follows: Tin and heat a bottom copper. Make a number of solder beads by holding the solder against the heated copper and letting the melted solder drop onto a piece of sheet iron or marble as shown in Fig. 14. With a brush apply the required flux to the scam of

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Figure 12.

the job, as shown in Fig. 15, then place one of the cold solder beads in the bottom of the work as shown in Fig, 16. rlfter heating the soldering copper, dip it into the dipping solution and hold it in con- tact with the cold bead until the solder begins to Row smoothly into the seam. The seam is finished by drawing the soldering copper slowly along the seam, adding additional beads as required and re- heating the copper when necessary (Fig. 17).

COOLING AND CLEANING SOLDERED SEAMS. Once the job has been completed, the work should be allowed to cool undisturbed until the solder has had an op- portunity to solidify. Movemerzt of the parts during

this cooling or pasty stage may result in a weak joint. Tiny- fractures sometimes set themselves up inside the joint and weaken it. Do not apply water to speed up the chilling of a soldwed joint until aft& the solder has had ample opportunity to reach the solid stage. Never ue water on soldered seams or joints that have been fluxed with a rosin type flux. There is no danger of corrosion if the residues of rosin are left behind.

Clean water, warm, if available, should be used


Figure 13.

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to rcn~ov~’ the residues o f all typs of acid fluxes. These residues, if allowed to sotten for abor:t 15 minutes aftel- soldc~ring, c:m be more readily re- mowtl with a final rinse in clean water. Then dry with it cle;m rag: as extra insurance against flux streaks and water stains.


Whwe it is impractical or impossible to make inter- locking bends in sheets or rods that are to be joined, tbew are several methods of reinforcing a butt joint. I~‘ipr(: J,R shnvs butt seams or joints that do not havc cnollgh strength and have to be reinforced.

:i sir~~pls method of reinforcing a butt joint on

sheet metal is shown in the left drawing, Fig. i3,

This type of seam or joint, called a bead seam, is fimned by first soldering the under portion of the metal in the same mxmer as that used for an inter- locked bend, then forming a reinforced strip of sol- der in the fol-m of a head seam on the upper portion of the two pieces of metal.

To make a bead seam, paste a piece of masking tape or “cellotqx” on exh of the sheets parallel to

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the two edges and approximately half of the width of the bead from each edge (Fig. 18). Apply flux to the space between tbe pasted-down strips. With a hot soldering iron, apply enough solder to form a bead. Place the edge, not the flat side, of the solder- ing iron in the center of the seam, and move it along as fast as the solder melts. The adhesive strips serve to keep the molten solder from spreading. Making a bead requires a little practice. At first the solder will be quite rough. Run the iron over the seam several ti,mes, until il smooth bead is formed.

Inothri- method of reinforcing seam joints is with a lap seam shown in the right drawing, Fig. 18. The two pierts of metal to be joined are overlapped and -;~~ltlrred in the position shown. The solder flows be- iwctw the two pieces and along each of the edges. 1’hi.s tq~ of joint is considered stronger than either the butt or the bead seam. When making a lap seam, use the flat side of the iron.

Auothrr method of reinforcing a butt joint is to solder 311 additional strip of metal between the two sheets of metal lengthwise with the joint.


Rods and bars, whether circular, square, or rectan- gular, must be reinforced with a collar of metal when butt-jointed. A short section of brass or copper tub- ing just large enough to slip over the rod can be used as a collar for a circular rod. For a square or rec- tangular rod, bend a piece of sheet metal to the proper shape to form the reinforcing collar. When fitting the collar, allow enough space to permit the soldn- to flow freely between the coUar and the rod.


Figure 17




Figure l?.

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Hold the Nat surface of the iron on the fluxed arex As the iron attains the proper tcmpcr;~tllre. the Hus will melt, bubble, and then smoke. When it smokes, do not wn~we the iwn from the wol-k. bolt apply thl. special aluminum solder to the copper aud melt it over the fhlxed swface of the ~hxninum. If addition;rl solder is needed to winforce or strengthen the joint, :?i:p!y it ::‘itb tbZ :iii i>f thr 11u11 iu illt? ti>Uili Illilllllt2T.

When soIdol-ilig other metals to alulninwn. it ir neccssal-y to USC ahuninum flux for the alrunin~~m and whichever Bux is required fur the other metal. \Vher-rver possib!r. xpply the heat to the underside of t!v2 ahlminum.

SOLI~EHING (;As~- km. Soldering cast ,xun is not cspr:ci:tll,y recommended. ‘but sometimes it is nwes- say to make temporary repairs in cracked cast-iron par-ts. \Viden the top of the crack with a cold chisel or a file, or by grinding it into a V-shaped gwove. The groovy shmdd be made wide and dwp rnougli

to pwnit a sufficirnt imwullt of soldc~r to entrr wd claw the crack (Fig. 20). Ckxn all g~waw dirt. rust, or pairlt fwm the cast iroa Xlost of thv aluminl!m Ilr~xrs can also be used for cast iron, but bcttrr TCL suits we obtained by using a special cast-iron Hus. Plnce the flux in the groove and on the surfacr SW- row&n;: the g~‘oo~~. Apply hwt until the flux smokes. The pra&~~- struchwe of iron castings make-: it necessary xxnetirnes to rqxwt the fluxing opera- tion several times before app!,ying the solder. Al& the solder and run it into the g~-nove with a hot cop- psr until the mtiw surface has been sol~lcrcd.

Sor.nsnr~r. BRASS AW HRONZE. Brass is an allov of copper with zinc or another metal. A HIIY of zinc

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chloride “I rosin is used for brass, and is applied in the usual manner to the cleaned surface. Be careful not to use too much heat. Then solder the parts in the manner described previously for the type of work. If zinc chloride has been used as a flux, the joined parts must be washed clean of all traces of it with water containing soap and washing soda.

Bronze is the general term used for various alloys of copper and tin. Some types of bronzes also con- tain zinc, silicon, lead, and nickel. Bronze is fluxed and sol&wd by the method just described for brass.

~o~or-nrsc IRON AN” STEEEL. Zinc chloride flux and till-lrad solder are satisfactory for soldering iron and steel; but the special commercial aluminum solders and Ruses give better results. The soldering proce- duw is the, same as that for other metals, according to the tqx of work.

SOLD~RZNC STAINLESS STEEL. stainless steel can be soldered satisfactorily if certain important factors are considered. Because stainless steel is a poor heat conductor. a relatively heavy copper must be used, and it must be held in one place on the stainless steel wniderably longer than is necessary when soldering other metals.

Special commercial stainless-steel fluxes are avail- able, but muriatic acid used undiluted is considered the best flux for the purpose. After cleaning the metal, brush the acid on the surfaces to be soldered and allow it to remain there for several minutes be- fore heginning to solder. The ordinary half-and-half type of solder can he used on stainless steel.

After the acid has been allowed to bite into the material, apply the solder with the heated iron, mov- ing the iron along the joint or seam very slowly. In fact, the il-on should be held on each spot before moviug it along. After the soldering has been com- pleted and the metal has cooled, wash off the excess

flux with a s”!utisn of washing soda and soapy water.

SOLDEHING LEAD, TN, PEWTER, AND Zrx. Lead has a wry low melting point--621 deg. F.-so the solder- ing copper must not be too hot. The flux and solder also must have a low melting point.

In lead soldering, the joints must be scraped bright and fluxed before the solder is applied. An ideal flux for lead is ordinary tal!ow. Scrape a few shavings of tallow on the joint and melt it into the joint. A special commercial tin-lead-bismuth solder, which has an extremely low melting point, must be used. Keep the soldering copper moving to avoid melting the surrounding metal.

Tin has a low melting point, and the p~owdiire given for lead soldering should be followed in solder- ing this metal.

Pewter is an alloy of tin, lead, and other metals. It also has a iow melting point, very near that of lead, and the procedure for soldering pewter is the same as for lead.

Zinc also has a low melting point, approximately 775 degrees. Use zinc chloride as a fiux, and the saxne solder and procedure as the lead. After so!der- ing zinc, wash off the excess flux with 7, solution of soapy water and washing soda.

SOLDERING WHIT* METALS. White metals are usu- ally combinations of lead, tin, antimony, and other metals that have a very low melting point. They vary to such an extent that specific directions for solder- ing them cannot he given without knowing which metals have been combined. As a rule, no flux is used on white metals. Clean the metal by sanding “1 scraping. Apply commercial tin-lead-bismuth solder with a wire brush before using the soldering copper. The general procedure for soldering white metals is approximately the same as for lead.

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Xvet:: are made of brass. .T ~i?er. wrought iron, tinned iron, mild steel, alun~~~~um~ and Alleghen! m&d. It is customary tc use rivets of the same metal as the parts that are being joined. Rivets have either wiid. !:oilow, or split shanks, and they have a variety ot hiwis. Types generally used for sheet metal work air shown in Fig. 1.

Round-head and flat-head solid rivets are more comnwnly used. Round-head and countersunk-head soft-jteel, rivets are avai!$+= 4,. z-*n*:- ., _ . . . ..,L,,dial sizes, rang- ing from 1.6 ili~ ?r- ‘Ii r 1 in in diameter, and in various iengths. Flat-head copper rivets are obtainable in SCVCE sizes, ranging in Iength from s/4 in. to 1:~; in.

Tinner’s rivets are available in twenty-four sizes, from ,050 in. to ,293 in. in diameter, and from 5/s in. to IT& in. in length.

Copper-pi&d steel and solid copper rivets are sold by weight in half-pound b,xrs, each containing an assortment of lengths and a burr; or washer, fol each rivet. The burr is necessar)- when copprr rivets are used. but it is optional with other types. It is slipped over the tail or end of the rivet-that part ol the rivet shank which projects through the work be- fore the end is flattened or mushroomed.

Rivet Setting Procedures

The usual tools required foi setting rivets are a ball-pen or a tinner’s hammer, a rivet set, and a rivet header. (See Figs. 3, 4, and 5.)

Use the Bat face of a tinner’s riveting hammer to flatten small tinner’s rivets. The flattened ends of either tinner’s or small rivets are never shaped with the tinner’s riveting hammer, but only with the rivet set and cup tooi, or header. A rivet set is s sma!l piece of hardened 2nd tempered steel wiih a hole in one end for the rivet head and either a conical or hemisphaical depression alongside the hole, for shaping tbr rivet end after i: has been flattened with the hammer.

Small rivets made of aluminum, copper, brass, or similar soft metals must be hammered lightly, and, naturally, will require a smallrr hammer. Larger rivets made of the harder types of m&ds will re- quire a heavier hammer. No set rule can be given for the correct size of hammer. A little experience or practice will quickly determine whether a hammer is too small or too large for the job.

Holes must be either punched or drilled in the



Finre 1.

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Figure 2.

met;%1 bcfr,re rivrting. Drills and p1uIches used and nwth&s <II using them are dt-scl~ibrd in Chaps. 3 nnd 4.

\\:hrl: ~INIW than CJIK rivet is used. all of the holes mt,st Ix lmpdy spawd and lined up. The spa&g of ri\-rts is determined h!; the nature of the work and the type of material used. III general. a good ru!e is that the mii,imum distance between rivrts should he thee diameters of the rivet stem, and the maximum. eight diameters. The minimum distance from the beige of the WL’I.~ sbonld be two diameters of the riwt stem. Rivets that are placed too close to the ~xlge wili cause the metal to stretch and tear. Too great a distawe from the edge causes buckling ::nd irxxening of the joint.

The length of riwt necessary to form a head suf- ficient fw the work deprllds on the ciearance be- tween the rivet and the iiwt hole, the type of rivet osrd. :md the tyx of mttal bring riveted. In general, till: riwt should extend frwn one to two diameters of its shank lxvond the material. The diameter of the ri\.ct should not he less than the combined Ackness of the sbrets that are being riveted.


Figure 3.

Rivets cr\n he set in either a single row or a double row, staggered as shown in Fig. 2. Narrow seams or joints are usually riveted with a single row in B straight line, while heavier material is usually riveted with a double row of staggered rivets, especially when the joint of the seam is to be reinforced with solder. Unless tlx rivets are staggered, there is a tendency for the hot solder to expand the metal be- tween them, causing the gaps and buckles iI\ the work. To prevent errors. drill all of the holes in one of the pieces, end w~lv olw h<llr in the second piwe. Secure the two piwr.< together with &her a rivet 01 a temporary bolt (A, Fig. 3). l?rill the rest of the

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h&s in the second piece, using those already drilkyl in the first as buidrs.

C!mp the two pieces tyt.thcr tightlv. Set thr rivet in the l%:,t holr with thr lirw~ i-rsting ;,g;,,,,t .I solid wrface. Strike the tail of the riwt se~yl-;~i clirrct blows with thr b:dl-prrn of your hamncr to expand the t.C! slightly beyond the edge of the ho!e (RI Fig. ~3). Pmceed to form the rivet to the wquirrd shape. b)~ working around its edge with the ba!l-pee11 at the proper angle (C. Fig. 4). Procrwl in the sanw

mamrr to form the bwd of the rivet ( D. Fig. 1). Continue to stl-ike imgui;u 1’. .,,thrr th;llg vrrtic;d bk~ws: vvl-tic;11 hlwrs Gil fom ;I fiat, p~~~~;.k-sh~~prd he:~l tii.ii is \vr;lhrr- thm :I ruunci or a cmic;d head. Thrn. I?\. IIGII~ the flat face of the !ia~nn~er. its in E. Fi!g. 3.





-- -I

Fijiwe 5 Figarc 4

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corrosion. ,9uminum alloy rivets make possibie the maximum savinq in weight and offer the greatest re- sistance to corrosion.

The riveting of alumi:aum and its alloys differs in maw ways from ttw orrii~iary riveting of steel or iron. The former optwtion must always be donr in a way to prodace tile greatest strength possible, and any distortion of the met&al must be avoided.

TI-PES OF RIVETS. The factors go wning the s&c- tion of rivets depend largely on the job to be done and the locztinn of the seam. Figwe 6 shows the common types of s&d shank rivets and Table 17 gives their general specificatmns.

In many cases where the rivets are to Ix subjected to shear stresses only, the appexawe of the heads mav wrll be the aetwmining factor. Huwever, whew it ii possible that SOIIK wnsile ::tress may he induced in the rii c t, cthcr noints must lx considered. In such c~*scs, a tvpe :,f rivet slio~lld be usrd in which the height w thickness of the iwad is not less than one- half the diameter of the rivet slunk.

~nund-hmd (r\, Fig. 6 j. This tape ui r-&t is used in reiatively thick sheets whew &engttr is required.

The size of the head is such that it covers sufficient arra tu strengthen the sheet around the hoie and at the same time offers considerable resistance to ten- sioa.

~ra:ier-l~~d ( B, Fig. 6). The bmzier-head covers st#jcirnt arce to <trengthen the sheet axxmrl the

.,.., - --




4 c D

” GpJ,?!Eh;-+!ELj

c C’f’SI,“rPEA~


Fii’m Fi.

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Shcuring rtrrngth

Type Material Identification (lb. per Remarks sq. in.)

--.-,-,.-~~~~ ~,~---,-

.4 .4lm~,imim alloy No. 2. Plain. 10,000 Du not heat treat before using. !

AD ~Alumimun allip N:r. h-liS. il dimpk in head. 25.OOfl Do not heat treat before using.

D j.41 uminom ailoy No. 1X. 11 raised tit on head. no.“t!o Hrst treat befon using.

1 ;.41unlinrnn “ll”?~ No. 24s. 1% raised dashes o,, head. :35,000 Heat treat before using.

/Iron ( cadmium Plated). /Plain. 35,000

c*nt~ierstrnk-hcud~~~f~~r~~~~k-heud (C. Fig. 6). This type 1s used ior riveting thick sheets over ivbicb other plates most fit. Countersunk-head rivets may also be used, in some cases, for riveting thin sheets.

Flat-bud (D. Fig. 6). The flat-bead type of rivet is sometimes used for internal riveting where in- creased clearance is required.

Special Ricet.9. Two special rivets are used to a certain extent in aircraft construction (Figs. 7 and 8).

Stcd T&k Ricet. Rivetr~ shown in Fig. 7 are not in the true SWISC tubular. The portion of the rivet shank tbrc;ugh tire materia: Is soiid and is only drilled to a depth sufEcient for hrading or up-setting. For this rewm, the Ierrgths must be very carefully matched in r&&ion to tine thickness of the materials


Figure 7.

through which they go. Rionuts. Rivnuts, shown in Fig. 8, are threaded

rivets manufactured from alloy number 53. They are

Type of screw

How,d brad I%1 hvad

-.-.-.,., *.- ___.~~.~~ ._._,. -- ..__~.~___

AN 51-i-(i-5 AN 505-R-S AN T,I.S.fi-H AN 505-N-B

AN SIWI-7 AN SOS-8-7 AN 515-O-7 AN 505-6-i

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Figure 6.




Figure 3.

used in places that are impossible to reach with a huckirq iron. The rivet is hollow sod the end “ppo- site the head 1 s ~5’ internal thread for approxi- mately one-halt Its length. The remaining length is countthmd to a somewhat larger diameter than the thread. The rivet is headed by meaos of a speciul tool with a threaded mandrel which is screwed into the threaded portion of the rivet. The tool bears against the head of the rivet and withdraws the man- drel which upsets the counterbored portion as shown in Fig. 8. Table 18 gives the general specifications for its use.

Rivnuts manufactured from 2, A-17, and 53 alloys have been heat treated by the manufacturer and no further treatment is necessary.

TYPES OF Jo;xurs (Fig. 9). The two standard joints used for riveting aluminum are the lap joint and the butt pint. Either type may be made with onr or more rows of rivets. In joints using more than one row. the rivets are usually staggered to distribute the stresses.

GENERAL ALUMINUM RIVETI~VG PROCEDURES. A large percentage of the riveting of aluminum is done on thin gauge aluminum alloy, and the work must be so accomplished that the material is r,“t distorted by hammer blows or injured with the riveting tools. This is done bv up-setting, or heading the rivets against a bucking tool of the tvpe shown in 10, instead of striking the shank with a hammer.


To prevent deforming of its head, a rivet set most he selected to fit each type. The depth oi this set must be surh that it does not touch the material bring riveted.

wht!!l so!id ri\&$ F’” Cmp!“tC!V throiis.i -1- hollow tubes, their diameter shonld be a; least one-eighth of the outside diameter of the tube. Rivets through hollow tubes which are loaded only in shear should be hammered just enough to form a small head. No attempt should be made to form the standard round hezd_ because the amount of hammering required often causes the rivet to buckle inside the tube, with resultant injury to the member. Correct and incorrect examples of this type of installation are shown in Fig. 11.

~lre sdection of the proper rivet for the various opl:r;ltiorls is very irnportaot arid roost be @en WE-

fld consideration. Table 19 gives the application of sluntl;wd rivets.

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Thr rivet should not be too loose in the prrviousl~ drilled hole, because this will cause it to bend ove,~ while being headed, and the sh;l& wili :\ot be suf- ficiently expndrd to fill the hoG completely (Fig. 9). A drill from .002 to .0&i in. largctr than the rivrt sboul:! be 11sct1 for sheet and plate riveting.

Pieces should be held firmly together by clamps, screws, or bolts while they are being drilled and I-iveted.





a?: .*-

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-,of ,-the:. j~mt-:sJio+$lje not less than two i&l&~&&i&: of the rivet from

In tubular tne!r,bers, where the rivets go txml-

$rteIp throi!gk the tubes; 3 mm.. hum dia:wier i;

est&&bed by taking one-eighth of the outside di- ameter of the tube. Where one tube sleeves over an- other, the xztside dixneter of the outer tube is taken. A good practice, in tnnny cases, is to use the next larger size of rivet than that obtained in the calcu- lation for th& minimum size.

Tnere are mmerons piaces in the original fabrica- tion of siructures where macbinc riveters caonot be used, and where the rivets Iraw to be hoaddup by hand, as described previously in this chapter. A iarge percentage of all repair work must also be arcom- plished by hand metkods, although mecbar?icaI I+ eters should be used wherever puss*bie. In order to be able to do good work, using any of the riveting methods, considerable skill is required together with a general knowledge of riveting practices. Figure 22 shows both properly and improperly applied rivets and brings out many commo~~ faults that must be avoided.

&ND OPEAATED SQUEEZE RIVETERS. Nunm-ous types of hand operated squeeze riveters are manw factwed and are used successfoXy for beading rivets not over ?h in. in diameter. Riveters of this type are ofteo med in the applicatioo of the cover on aircraft using the stressed skin type of construction. Specific directions for their use are furnished by the monu- factmer.

For bucking rivets inside of round or ova&shaped tubular members and straight channel sections, an expanding tool is used. Two such bucking tools are shown in Fig. 10.

SQUEEZE RIVETING. Many machine riveters in gen- erai use are of the squeeze type operated by air pressure. They are manufactured both as portable and stationary units, although the portabie riveter is the most satisfactory for general work. The air pies- sure required to operate these riveters is between 80 and 100 lb. per sq. in. Squeeze riveting is the most efficient method insofar as the strength of riveted joints in aluminum is concerned. The rivet is up-set

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I &

be 1~1~1 ir! clcse contact svhile being xiv&d. WIPI!

ti\w pieces of metal are dri!ied togethurz as is the

GISP i!l m;,st rivctin~ wwk, the drill has 8 tendency

: ‘+a ~~ise:the’first~piece”~~~y,frpm, the, f,oyer, or s~~~ot$ ” .,., ,, ~,’ p@cei’if, $+y,:+ tibt: ,@l&tog+h& tightly.:,,~i3:‘:al-:i’

‘::,:If ? _’ 106 burrs 6~ &ipi,td ~&&$A between the two piecc$

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,,,,, ,,, ,,, ,,


Pop Rivets

Pop rivets (Fig. 15) have two advantages com- pared to standard rivets in that they can be set by one man ami also be used for blind fastening. This means that they can be ased where there is limited or no access to the reverse side of the work.

Operation is simple. Drill boles in the parts to be riveted together and align the holes. Insert the pop rivet ia hollow rivet assembled on a solid mandrel) and set it with a pop riveter (Fig. 16) using the pro- cedure showu in Fig. 17.

There are two basic designs for pop rivets: closed- end and open-end (Fig. 15). The &se&tad type rivet fills the need for blind rivets which sea! as they are set. They are gas- and ~q~~dtigbt~ when used properly. since ;I high degree of radial expansion pro- vides escellent hole-,filling characteristics and the tnundrel lrexl is within the axe d the rivet body.

The o~ren-end type is not ~~qw~~tigbt because the mandrel bd which remains in the rivet body is not enclosed within that body as is the closed-end type.



This obviously leaves room for possible seepage of liquid or gas.

Rivet Selection

The following rules govern the selection and use of rivets in making a repair:

1. Replacements must not be made with rivets of lower strength material unless they are larger than those removed.

2. When rivet holes become enlarged, deformed, or otherwise damaged, use the next larger size as re- placement.

3. Countersink head rivets are to be replaced by rivets of the same type and degree of countersink.

4. Rivets selected for specific applications must always be of the type recommended in the repair manual for that particular piece of equipment. Rivets are available in a variety of metals and alloys having specific shear strength and hardness characteristics. Selection of the wrong alloy-type rivet could produce hazardous results.

Figure 16. Pop rivet tds.

Figure 17. Setting pop rivets.

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Chapter 8

Sheet Metal Fasteners

Many mechanisms and devices are held together x&h metal fasteners. Only the more commonly used fasteners wiil be discussed here so you will know when. where, and how they should be used. Use the fastening device that is best suited for the job.

Shed Metal screws

iIarder.ed sheet metal screws are used for fasten- ing or joining sheet metal parts that cannot be riveted. These screws are known in the trade as “self- tapping” screws (Fig. 1). The following tables give

the sizes of screws and drills to be used for metal of different thicknesses.

As shown in Fig. 1, both blunt and sharp pointed screws are available. In general, the blunt end screws will be found most satisfactory, but the pointed type is used if alignment of the holes is dif- ficult. In all “self-tapping” screws, the letter Z de- notes the blunt or square end while A indicates the gimlet or sharp point.

Type A screws are usually used for joining ma- terials lighter than ,050 in.

Type Z screws are usually used for sheets from .015 to .203 in. thick.






011. DIA.


Figure 1.


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fastening. When a part in which B clearance hole is provided is to be fastened to light gauge sheet met;d, it is dwimble to pierce or extrude the hole in the latter (C, Fig. 3). Hecommended hole sizes we given in Table 20.

PnocEoonl~s FOH USING TYPti 2 S&W-TAPL’ING Suwws. The type 2. hardened, self-tappiping screw, shown in Fig. 4, was designed to extend the many advantages of the original sheet metal screw (the type A) to a broader range of applications. With the type Z, secure fastenings are made simply sod inex- pensively to light and heavy gauge sheet metal, non- ferrous cestiogs, and sheet metal parts to rosin




I;ipw 2

are ;dso :twilablr in appt.wimately the some size r;nr~~* as the “self-tapping” SCWWE. These screws IP- q&ire a spwi;tl screw driver for wch size of head.

Y~~octm~n\~ VOH USING Trw A SIIW~ METAL Scnt:ws. Whrn twcr parts mxdc of light g;wgc sheet

twtd mx to be joind. the holes in both way be drillwl or cI~~~II-~~IIIIcIIc’~I with a stop pnncb (Fig. 2) Ihe siuw sizr. using tbv bolr size rwomn~endctl for tbn total nwtal thickmass (A, Fig. 3). or the holes in both tbicknosses may be pierced at the s~wn~ time in a nested form (B. Fig. 3): wbirh results in a stronger


No. 4

No. 6

No. 7

No. n

No. IO

No. 12


Nu. 14






s “M

ia.@ N”. - 44 44 42 42 4U

39 39 39

.X)8 ”





.UY3” ,993” .998”




.lQl” ,108”

.lat” ,104” .llO” ,113” .llW .12w

..~...-_“. .113” .I 13’ .115- .120- .128”


.128” ,128” ,136” .14R”

,147” ,149” ,152’ .157”

.IHO” .IHn” .191” SUB”

,015” SJl3” ,024” .(AW .03W’

,015” .01X” ,024 ” .MO- .036”

,111” .lil” .111” -I-


.Oltl” ,024” .O%J” .0:3H” .04X”

3i 37

ii 32 31

,” 32 31 30

i -.

I ,,... --

,120” ,120” .12U” .12w

.I36” ,138’ .13fl” .136”


.024 ”




,018” ,024” .aw .OGB” .MH”

,,.__I ,024” .O30* .(L’UY .MH” .---., ,024” .onv .xX3” .Q4R” .-_,.-, ~


,157” ,157” ,157” ,157”

,185” ,185” ,185”

,208” .2w .2w __-,..-__



Fiptm 3.

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-a NAILS 221

impregnated plyw , bard rubber, or slate. ThetpZiSh ned, so that it forms a mating

thread as it is driven into a &i or punched hole of suitable size. Fastenings made with-type Z resist vibration, tension, and shear stresses. To drill the w?cessary hole, my conventionai saew driver can moved and repia y wrthout impairing security.

Because they eliminate isq,@g and threading and because of the obvious sa?tig tiar time, trouble, and costs, these type Z scmws have replaced m.&b~e screws, belts, rivets, aed other d&e for n;any metal assemblies the sheet metal indus- try. They are av bgb the ti:nventional siotted head and tb ssed head (Fig. 5).

When two parts made of sheet metal are to be joined with type Z s ; tbe boles in bo% may be drilled or clean-pun the same size, !Ising the hole Sk re~~~end~ in 1 for the total metal t&kness (A, Fig. 4 irrboth thicknesses

~, may be pierced at same time in-a nested &III

(B, Fig. 4), which resu!ts in a stror,ger fastening. When a part in which a clearance hole is provided is to be fastened to light gauge sheet metal, it is de- sirable to pierce or extrude the hole in the latter (C, Fig. 4). Pierced or extruded holes are not necessary when the screws are used in relatively heavy gauges of sheet metal as iodicated in the hole size (see Table 21.)


xlany types of conventional nails made of zinc coated and tinned copper are still used for fastening sheet metal work to wood and masonry. However,


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the type of tinner’s nails shown in Fig. 6 are grad- dy being discarded.

and securely to wood is solved by the hardened

The pmblem of fastening sheet metal economically screwnail (Fig. 7), which combines the easy driving qualities of a nail with the strong holding property


.015" ,018" .024” .(Mo” .036” ~048” .060”

.015” .018” .024” .a3w .03w a48 .w .075” .105”

.015” .018” .924” .030- ,036” .048” .ow ,075” .105” .126”





.036” .Mll” .ot?w .075” .lOY .128”


.018” ,024” .W3W .036” .X146” .ofw .clw

STIlN rmONm..

&Y”% “Ok

ml‘. Pnldrnl






All” ,111” .lll” ,111” ,111”


.120” ,120" .lZo” .lW

,136” .136" .1.3fY ,136" ,138"






.111” ,111” ,111” .lll”

,120” _--.





.136" ,136" ,138" ,138"



.12R” ,136” ,140”

1. -



.12Y ,135" ,162"

t” ,315' - ,018” ,024" .l30” .036- .046" .060" ,075" .105” ,125" ,135" .164" .2000"


,024" ,030" ,036" ,046" .ofw ,075" ,105" ,125” ,135" ,164” ,200”


,030" .ORR" .04R” ,060" .075" ,105” .125” ,135” ,164” .fR7” .194” .?rlo”

STAIN dOXEL -2 -- PiPrnd nr

%%" -c

""I,. Ra,uiml

.1.57" ,157" .157" ,157" ,157"





~- ,209" .209" ,209"

- -7 *wed c ‘;w”,“I:”


1lOk L~qlll,PI


157” 157” 157” 157”





:iEC am” ,070” ,073” ,073” .076”

- .086” .%3w .089” .093” .093” .096” .099” ,101”




.106” ,110” .111” ,116” .12W .128”



.llW ,118” .120~ .lW .13w .140”

.118” ,120” ,120” .128” .136” .140”

sz 52 51 50 49 4Y 48

z 44 43 42 42 41 39 38

;5i 37 :36 36 35 34 32 31 .36

Gj .33 30 ii 31 30 29 23


ii 31 31 30 29 28

,149” .149” .152”


,144” ,144” .147” .152* ,152” ,157” ,161” .169” .169” ,173”


27 27 26 24 24

:FJ 16 18 17

19 19 19 16 16 14 13 9 9 7

-- m,r LI~I,IIIIPtl

,147” .147” ,149”


,144” .144” ,144” ,147” ,147” ,154” .154” ,159”


.161” ,166” ,173” .lRO” ,182” .182” .189”


,199” ,201” ,204” .209” .209” ,213” ,213” ,221”


E Pill

zs 26 25

24 -

27 27 27 26 26

ii 21


: 6 4 4 3 3 2


ii 52 52 51 50

No. 2

No. 4

44 44 44 43 43 42

NO. 10


i; 36 35 34

,166” .lGB” .166” .lfW ,177” .lH2” .1X5” ,198” ,198” ,201”

.1X5” ,185” ,191” ,199” ,204” ,209” .22R” ,228” ,234” ,234” ,234”

NO. 12

NO. 14

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Figure 6.

of it r~rtw. Unlike ordinary nails, these screwnails ” do IKN break or bend, nor do tbey work loose, back ,:,:out, or pull out. Tbe hardened spiral threads cut into I!i the burr formed in the sheet metal by the pilot ;;;: (smooth portion above the point) (Fig. 7) and ;;,‘:, worm their way into the wood, holding the sheet :‘,:,~metal and wood together as though they were ,, ‘i clamped in a vise.

Due to the greater strength of tbe fastenings they ‘,i, make. fewer screwmails are needed to do a job, thus “~ speeding up the work and lowering the cost. Screw-

nails are used extensively by tiosmitbs and roofers, and by manufacturers of automobiles, buses, railway cars_ refrigerators, signs, billboards, and other prod- ucts involving sheet metal-to-wood fastenings.


Figure 7.

They are also available with cement coating, for increased holding power in wood. In such applica- tions, the cement acts as a bonding agent between the wood fibers and the threads of the screwnail.

P~ocrzmnm FOR USING Scmw~arrs. Drive the screwnails through sheet metal into wood the same as ordinary nails are hammered into wood. If the sheet metal is too heavy for the screwnail to pierce it easiiy, a hole should first be punched with a screwnail punch (Fig. 8). An ordinary prick punch can be used if a screwnail punch is not available, but care must be exercised to avoid making the hole too large.

Note how the hardened spiral threads of the screw-4 cut mto the metal and worm into the wood like a screw (A, Fig. 9). No punch was used to make the hole-the hardened needle point pierced the metal with ease. Now observe the fit of the cwdinuy nail in metal and wood ( B, Fig. 9). Tbe hole in this metal was punched, because the nail would not pierce it without bending. The holding power of the ordinary nail is by friction alone; there is no engage-


Figure R.

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Fig,,re 9.

ment in the metal. Eventually, vibration or expansion ;u~rl wntraction will cause the nail to loosen and will \\.~wkvt, the structure.

Screwnails are available in the standard bead styles showu in Fig. 10, sod sizes sod weights shawl in Table 22.


.pproximate ?y$$


105,000 eo,oiJo .SO,OOO :37,000 22,000 20,CHKJ 15,000 12,000 10,000

105,000 92,oao 70.000 55,000 45,ooo


85,olm 65,000 45.000

Another type of special nail used extensively by she& metal workers is the hardened masonry nail (Fig. 11).




Figure IO.

These unique nails provide a simple. in&pensive. yet thoroughly satisfactory means of fastening sheet metal to brick, concrete, and other masonry. Made of special grade steel and heat-treated. they will not easily bend or break. Furthermore, the ribs become embedded in the masonry, thus strvugthming thr fastenings.

Masonry nails are available in the stamlard sizes shown in Table 23.



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1,/s” “&” “&”

‘lk ” l/i ” VI ”



% ” 1"

1%" l'/r', 2"


l/z lb. $5 “

1% “ 2% " 3% ‘l. 4


e lAppr~ximate I ’

Approximate Npq;hrxa Quantity in a

100 lb. keg


207 20,700 120 12,000 72 7,200 40 4,000 32 3,200 26 2,600

Hardened mas”c;y nails are simple to “se. They can be hammered into mort;lr, cinder blocks, and other comparatively soft masonry the same way ordi- nay nails are hammered into wood. When used in coocrrtc, brick, or other hard substances, it is neces- sary first to drill a hole of the proper size about two thirds of the length of the nail. For making the holes, masonry drills are recommended.

The drill-bit-holder of the masonry nail drill shown in Fig, 12 is made of tool steel, heat treated to resist “mushrooming” of the hammer end. The drill-bits (Fig. 12), forged of vanadium tool steel, stand up unusually well. The spiral flutes prevent binding and, when the drill is rotated slightly between blows, they serve to extract the puiverized material from the base of the hole, When dulled, the drill-bits are easily regroond like twist drills. They are furnished in the following sizes:

1h” For “se with ;/x” x 3~” Masonry nails

5/3s” For use with 5/3y” x 1” Masonry nails 3i6” For use with y16” x lj/,” Masonry nails

$c x 1l/z” Masonry nails Sk” For use with j/4n x 2” Masonry nails

f/4” x 21/,” Masonry nails

Light, rapid blows increase the cutting speed of a drill, prevent binding, and extend the life of the drill.

Fasteners for Copper Sheet Metal

Because the right types of fastenings are essential to the proper installation of all sheet-copper work, these definite rules should be followed:

1. All fastenings should be of copper or a copper alloy.

2. Never secure sheets in any way that will pre- vent some free m”vement.

3. All pieces of copper forming parts of roofs, tanks, or other large units, should be cleated.

4. Fasten copper flashings more than 12 in. wide with cleats.

Rule 1 merely is an application of the principle that dissimilar metals must never be in contact. This applies not only to nails, but to hangers, brackets, braces, and screws and rivets. This basic rule is espe- cially important when working with copper.

Rules 2, 3, and 4 are corollary to the fundamental rule that provision must be made for expansion and contraction when working with copper. Cleats per- mit such movement, and also restrict it to each sheet, so the movement is not multiplied throughout the entire copper work.

Figure 12.

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Strips less than 12 in. wide, such as flashings and edge strips, may be secured by nails. In such in- stances, the nailing should be restricted to one edge. Nails should be near the edge and evenly spaced, not more than 4 in. apart.

A common source of fIashing trouble derives from failure to observe rules 2 and 4 in valley flashings. These, by their very nature, are csually from I6 to 24 in. wide, and must be secured on both sides. Fig- ure 13 shows a valley flashing. If such a flashing is nailed, two things may result from movelrznt through extreme temperature ranges: the flashing may tear at the nails and become loose, or the sheet may buckle along the edge of the roofing material. With the first, water works under the loose flashing;

with the second, splitting or cracking occurs from fatigue of the metal.

Cleats for Copper Work

Cleats should be made of M-ounce cold-rolled copper, not less than 2 in. wide, and should be fast- ened with two copper or copper-alloy nails as shown in Fig. 14. A width of 2 in. is preferable, because it give; a stronger cleat and minimizes the possibility of the nails tearing out. The nails are placed parallel to the edge to prevent turning. The end of the cleat is bent back over the nails to prevent the nail heads from cutting the sheet. The length is determined by the kind of seam with which it is used.


Figure 14

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kfaximum spacing should not exceed I2 in.; a spacing of 6 or 8 in. is recommended. This does not apply to concealed valley flashings, where the sheet or strip is held by the roof covering. Under these conditions the spacing may be increased consider- ably; a maximum of 24 in. is recommended.

The cleat holds the sheet as shown in Fig. 13. If it also secures a second sheet, it is folded in with the sheets as the seam is formed. In such cases, the cleat must be nailed down before the sheets are brought together.

COPPER AND COPPER-ALLOY NAILS AND SCREWS. Many flashings, such as gravel steps, those around window and door openings, and some cave strips, must be nailed. In these cases, the four rules for fastening previously given in this chapter are still obsrr\;ed, for the copper strip is fastened along one t~lgc only. and is free to move in a direction normal to the line of nailing. The longitudinal movement i,s taken care of by placing the nails a short distance (4 ,in. is the recommended maximum spacing) apart. hs the total movement, through a temperahue of I70 deg. F., between nails spaced even as much as 12 in. will be less than l/50 in., there is little danger of tearing or splitting because of strain.

” The cost of nailing with nails spaced 4 in. is not enough to justify risking failure of flashings at such vulnerable places as wall openings and roof edges.

Tbe folly of using iron or steel nails with sheet copper cannot be over-emphasized. No economy re. suits born saving a few dollars in nails that quickly corrode and thereby bring about failure.

The proper nails to use with sheet copper are large flat-head wire nails, not less than I2 gauge, with barbed shanks and diamond heads (A, Fig. 6). These are known as “copper wire slating nails,” and differ from ordinary wire nails in the design of the head and the shank immediately under the head. The barbs at these points act like diminutive fish hooks in the wood fibers. As can be seen in B, Fig. 6, the ordinary wire nail has a ridge or shoulder under a smaller head. This makes it impossible to drive the nail home without tearing the sheet around the clean hole formed by the shaft. Moreover, the smaller head does not have enough gripping surface to hold well.

Cut nails regularly used for shingles and tile roof- ing are shown at C and D, Fig. 6. These nails have a greater holding power (2 or 3 times) than wire nails of the same length, but their disadvantages for use in sheet copper work are obvious. The shank tears the sheet. and the head, if driven home,

punches through. For ordinary use in wood sheath- ing, the holding power of the large flathead wire slating nail is satisfactory.

In exposed locations, or wherever a special hold- ing power is required, heavy (10 gauge) wire nails with barbs the full length of the shank are recom- mended. Cement-coated nails and etched nails also develop tremendous gripping power when the metal is nailed to wood.

The list of copper wire slating nails given in Table 24 has been set forth by the U.S. Department of COIII- merce, with the approval of the industry, through the National Bureau of Standards, under Simplified Practice Reconrmendation R150-34.

Length ( Inch )


1 1% 1% 1% 1% 1% 1% 1% 2



i I Stubs’ Gauge

kcimal Equivalenl (Inch)

Apror. Number to the


12 12 11 10 1P 11 :0 10 10

0.109 0.109 0.120 0.134 0.109 0.120 0.134 0.134 0.134

292 240 208 164 204 164 132 I.18 108

Cut slating or roofing nails of brass and Naval brass are standard for slate and tile roofs, where large nai!z (2 in. or longer) of considerable holding power are required. The length of the nail neces- sary to give sufficient penetration into the nailing base, which is often gypsum or nailing concrete, de- mands an alloy harder than copper.

Cut slating and roofing nails of brass and other copper alloys are also used to attach slate and com- position shingles to roof. They are like ordinary cut copper nails, except that, to get more holding power, they are made from heavier-gauge material and with larger heads.

Special Fasteners for Metal Gutters, leaders, and Roof Drainage Systems

The drainage systems of all roofs are designed to carry water away quickly and to avoid pockets in which snow and ice can collect. The basic designs of roofs, flashings, and valleys are unaffected by the

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type of material used. They should shed water di- INSTALLAT~N OF CIJITERS AND LEADERS. When iu- rectly and speed& to gutters. the outlets of which transfer their h&mtal Ilow into vertical leadrl

stalling gutters, leaders awl other parts of the roof drainage system, the use of copper is recommended.

low with maximum efficiency. Sheet metal units While the initial cost of coppc: is slightly more thiu comprising a complete drainage system we available that of other metals, it is nowcorrosive and will be io various styles and sizes and require only assembly found more txowmical over a period of years. and cawct fastening (Figs. 15 and 16). Copper gutters, leaders, hangers, hooks, and other










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necessary accessories are available in different sizes and forms at local dealers, ready for installation (Fig. 16).

The different types of gutters that are fabricated of 16-ounce cold-rolled copper in various sizes are showo in Fig. 17. The moulded copper gutters illus- trated conform with the SimpZi@d Prmtice Recm- n~o&tions R 2942 (United States Department of Commerce) made e&ctive February 1, 1942, and generally followed by the trade. The gutters shown in the two upper left illustrations of Fig. 17 are made to rest upon the roof near tbe eaves, and the p+cb OE fall of the gutter is farther away from the eves at the high point than at the low point. Attach

light copper bars at the front, nail to the roof at the top, and cap with copper to prevent leakage.

There are many kinds of copper hangers on the market, and most of them are satisfactory for the special conditions for which they are made. The sev- eral varieties shown in Fig. 18, by no means a com- plete selection of those available, wili serve for all ordinary purposes.

Figure 18 illustrates some of the bronze and cop- per shank-and-circle-type hangers, which may be made of either cast or wrought metal. They can be adjusted to give the gutter the necessary pitch by attaching the circular part to the shank at different heights. If the exterior is to be painted or stuccoed,





Figure 16.

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the shank is normally attached before this work is done and the gutters hung afterward, thus avoiding the chance of damage to the gutters by the necessary sc.&olding and ladders.

Figure 18 also illustmtcs three common types of leader books. These, if desired, can be obtained in two pieces-the clasp part separate from the shank. Shanks are available in different lengths, designed either for wood or brick drive. These leader hooks are driven into the wall before the leader is placed. Leader hooks generally should not be spaced farther than 6 ft. apart; in auy case there should be at least one to each 10 ft. length.

A special type of ornamental cast brass leader strap with removable front is available. This can be put in position before the wall is repainted or stuccoed and tlw leaders set in place later.

I..r:&rs or conductors are made and stocked in few differmt shapes. Plain round leaders do not resist freezing as well as do the corrugated ones. hloreover, the latter are more pleasing in appearance than are the plain ones. Sixteen-ounce leaders are regularly furnished in 10 ft. lengths.



Figure 17.

All outlets should be provided with strainers. Strainers are essential when the leaders are small, or whet they have elbows where leaves are likely to stick and clog. Wire basket strainers of stock design are gcnrrally carried by jobbers and sheet metal contractors. Strainers of heavier design, however, can readily be made up to desired specifications. Heavier- cast brass strainers should be used for drainage out- lets on promenade tile or composition roofs.

One illustration in Fig. 16 shows the adjustable copper gutter shank nailed to the facia board, and the other shows it nailed on the roof. Proper placing of flashing strips is also shown in the same illustra- tion.

A copper rod :!/H in. in diameter may be driven into a $5 in. bead of a stock gutter for reinforcement. These rods are recessed 21,; in. at one end of a



Figure 18.

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section of gutter and extended 1% in. at the other end to form an interlock between sections with 1 in. lap.

The strap hanger shown iv Fig. 19 is clamped at the back of the gutter and is spaced not over 30 in. on centers. The sustaining strap regulates the pitch of this gutter. An expansion joint for long sections is also shown.

Moulded gutters (Fig. 16) are set in a position to receive the drainage, but low enough to prevent snow slides from injuring the outer edge. They are usually set level because of architectural considera- tions. Where the brass spikes are used, they should be nailed into rafter ends. Pressed sheet copper straps are available to fasten gutters back to the roof. Ex- pansion joints, shoxvn in Fig. 16, should be used in long lengths of this type of gutter. It is important to keep leaders f/4 in. from the wall to avoid staining in case freezing causes breaks in the seams.

Cold-rolled copper is frequently used for the !ining of wooden gutters. Two typical designs are shown in Fig. 20. Note that the outer edge of the copper gut- ter lining is loose-locked over an edge strip, which also forms a drip. The inner edge is loose-locked into a flashing strip along the sheathing. Flashing strips are attached with narrow cleats to prevent nailing through the copper.

INSTALLING CIIKXJLAR G~~~EBs. Half-round gutters are installed on circular towers, or on bay windows with large radii, by using short sections of straight gutter formed without the bead. Section a brass rod covered with a strip of copper into long lengths, and solder it to the circular gutter. Arrange the adjust-

able copper gutter hangers to conceal the cross joints in the gutter.

If, however, the radius is not large enough to per- mit the use of small sections of straight gutter, make a circular gutter by joining front and back sections throughout with a bottom strip cut to a radios slightly larger than that of the wall line (Fig. 21). Obtain the radii of the two conical pieces by extend- ing the dotted lines a-b and c-d to a vertica! line in the center of the tower. Stretch the blank piece of the rear section over a mandrel. Raise the other on a block that has been cut to profile.

Draw the bottom member of the rectangular gut- ter to the radius of the wall line, adding y2 in. for thickness of the gutter hangers, and draw the second curve in front of this to the exact projection of the gutter. The vertical member in the back of the gutter has an edge hemmed at the top, and a small edge turned at 90 degrees at the bottom as a lap for sol- dering. The bottom front member has a quarter- round bend at the top, which is stretched to the proper curvature before it is soidered at the bottom. The next strip has two edges turned in as soldering laps, and the Bat strip at the top is cut radially. This gutter is supported by copper bar hangers, Which are nailed to the woodwork in the back.

In the left illustration of Fig. 22, an opening is cut into the stone cornice to permit the leader to run in a straight line. A little clearance between the leader and the stone may prevent discoloration of the stone cornice.

The center illustration in Fig. 22 shows the proper



Figure 19.

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Figure 20.












Figure 21.

The center illustration shows provision for nailing the ewe strip where the concre+e is covered with insolation. method of elbowing to conform to the profile of n

stone belt course. TABLE 25 The right illustration in Fig. 22 shows the leada

on the front of a building connected to a drain lo- APPROXMATE AREA OF LE~lmll 11% sQV.UE hCHE§

cated on the side of the building. Nominal Figure 29 illustrates a method of fastening gutter Leader Size Plain Cormgatcd Corrugated

hangers to concrete-and-wood sheathing where roofs in Inches Round Round Rectangulw

are covered with composition roofing. The hangers 7 6 8 should be let into the slab so that the tops are flush : 11 12 with the deck. and should be secured to the concrete 5 ki 18 19

slab by brass nails or bolts in expansion sleeves. I3 28 28 -

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Figure 22.


M <

Figure 23.

The left illrlstration shows the gutter attached to wood sheathing.

Leaders are usually located near the co~wrs of the building to avoid retarding the flow of draioage, and to eliminate sharp turns in the gutters. The ap- proximate required leader area is given in Table 25

Otre sqwre inch of leader area will serve aplm~x- imately 200 xl. ft. of actual computed roof area for an awwge 6 in. intensity of rainfall.


MACHINE Bovrs. Machine bolts (Fig. 24) are made with National Fine (N.F.) or National Coarse (NC.) threads extending in length from twice the diameter of the bolt plus l/4 inch (for bolts less than 6 inches in length), to twice the diameter of the bolt plus l/2 inch (for bolts over 6 inches in length). They are precision-made and are generally applied

metal-to-metal where close tolerance is desirable. The head may be square, hexagon, younded, or flat countersunk. The nut usually corresponds in shape to the head of the bolt with which it is used. Ma- chine bolts are externally driven only. Selection of the proper machine bolt is made on the basis of head style, length, diameter, number of threads per inch, and coarseness of thread. The hole through which the bolt is to pass is bored to the same diam- eter as the bolt. Machine bolts are made in diameters from l/4 inch to 3 inches and may be obtained in any length desired.

STOVE BOLTS. Stove bolts (Fig. 24) are less pre- cisely made than machine bolts. They are made with either flat or round slotted heads and may have threads extending over the full length of the body, over part of the body, or over most of the body. They are generally used with square nuts and ap-

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meen, NEcI(


Figure 24. Types of bolts.

plied metal-to-metal. wood-to-wood, or wood-to- metal. If flatheaded, they are countersunk; if round- headed, they are drawn flush to the surface.

EXPANSION BOLT. An expansion bolt is a bolt used in conjundion with an expansion shield (Fig. 24) to provide anchorage in substances in which a threaded fastener alone is useless. The shield, or expansion anchor, inserted in a predrilled hole expands when the bolt is driven into it and becomes wedged firmly in the hole, providing a secure base for the grip of the fastener.

Copscrews perform the same functions as machine screws, but come in larger sizes for heavier work. Sizes range up to 1 inch in diameter and 6 inches in length.

Capscrews are usually used without fists. They are screwed into tapped holes, and are sometimes referred to as tap bolts. Threads may be either NJ. or N.C.

Capscrews may have square? hex, flat, but:on, or fillister heads. Fillister heads are best for use on moving parts when such heads are sunk into counter-

bored holes. Hex heads are usually used where the metal parts do not move.

The strongest capscrews are made of alloy steel and can withstand great stresses, strains, and shear- ing forces. Capscrews made of Monel metal are often specified on machinery that is exposed to salt water.

Some capscrews have small holes through their heads. A wire, called a safety wire, is run through the holes of several capscrews to keep them from coming loose.


Setscreus are used to secure small pulleys, gears, and cams to shafts, and to provide positive adjust- ment of machine parts. They are classified by diam- eter, thread, head shape, and point shape. The point shape is important because it determines the holding qualities of the setscrew.

Setscrews hold best if they have either a cone point or a dog point, shown in Fig. 25. These points fit into matching recesses in the shaft against which they bear.

HEALGQS SETSCREWS. Slotted, Allen, or Bristol types of headless setscrews are used with moving parts because they do not stick up above the surface. They are threaded all the way from point to head.

COMMON SETSCREWS. Common setscrews, used on fixed parts, have square heads. They have threads all the way from the point to the shoulder of the head.

Trm~s SCREWS. Thumb screws are used for set- screws, adjusting screws, and clamping screws. Be- cause of their design they can be loosened or tightened without the use of tools.


SQUARE AND HEXAGONAL NUTS. Square and hex- agonal nuts are standard, but they are supplemented by special nuts (see Fig. 26). One of these is the iam nut used above a standard hex nut to lock it in position. It is about half as thick as the standard hex not, and has a washer face.

CAS~LIATED NUTS. Castellated nuts are slotted so that a safety wire or cotter key may be pushed through the slots and into a matching hole in the bolt. This provides a positive method of preventing the nut from working loose. For example, you will see these nuts used with the bolts that hold the two halves of an engine connecting rod together.

WING Nvn. Wing nuts are used where the desired

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:,, : ;,, :,,, ;, 3:;~; ;:>,, ,,:,: _i,,,









Fignre 25. Setscrews and thumbscrews.

degree of tightness can be obtained by the fingers. Cnp nuts are used where appearance is an important consideration. They are usually made of chromium plated brass. Thumb nuds are burled, so they can be turned by hand for easy assembly and disassem- bly.

ELAS~C STOP NUTS. Elastic stop nuts are used where it is imperative that the nut does not come loose. These nuts have a fiber or composition washer built into them which is compressed automatically against the screw threads to provide holding tension. They are used extensively on radios, sound equip- ment, fire control equipment, and on aircraft


Figure 27 shows the types of washers commonly used.

FUT WASHERS. Flat washers are used to hack up bolt heads and nuts and to provide larger bearing surfaces. They prevent damage to the surfaces of the metal parts.

f3 sau/\RE - JAM CpsrmpiTED


SPL~ LOCK WASHEHS. Split lack washers are used under nuts to prevent loosening by vibration. The ends of these spring-hardened washers dig into both the nut and the work to prevent slippage.

SWAI(EPROOF LOCK WASHERS. Shakeproof lock washers have teeth or lugs that grip both the work and the nut. Several patented designs, shapes, and sizes are obtainable.

Keys and Pins

COTTER KEYS. Cotter keys (Fig. 28) are used to secure screws, nuts, bolts, and pins. They are also used as stops and holders on shafts and rods.

SQUARE KEYS AND WOODRUFF KEYS. Square keys and Woo&# keys (Fig. 28) are used to prevent hand wheels, gears, cams, and pulleys from turning on a shaft. These keys are strong enough to carry heavy loads if they are fitted and seated properly.

TAPER PINS. Taper pins (Fig. 28) are used to lo- cate and position matching parts. They are also used to secure small pulleys and gears to shafts. They usually have a taper of l/4 in. per foot. Holes for


Figiue 26. Types of nuts. Figure 27. Washers.

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Figure 28. Keys and pins

taper pins must be reamed with tapered reamers, or the taper pin will not fit properly.

DOWEL PINS. Dowel pins (Fig. 28) are used to position and align the units or parts of an assembly. One end of a dowel pin is chamfered, and it is usu- ally ,001 to ,002 inch greater in diameter than the size of the hole into which the pin will be driven.

Turnlock Fasteners

TurnIock fasteners are used to secure doors, in- spection plates, and other removable panels on items of support equipment and aircraft. These fasteners are also referred to by such terms as quick-opening, quick-acting, and stress panel fasteners. The most desirable feature of these fasteners is that they per- mit quick and easy removal of access panels and doors for inspection and servicing.

Turnlock fasteners are manufactured and supplied by a number of manufacturers under various trade names. Some of the more common trade names are the Camloc and Dzus (pronounced zoo’s) types,

CAMLOCK FASTENERS. Camlock fasteners are made in a variety of styles and designs. Regardless of the particular style or shape, the Camloc fastener con- sists of a stud assembly, receptacle, and a grommet (Fig. 29).

The stud assembly consists of a stud, a cross pin, spring, and spring cup. The assembly is so designed that it can be quickly inserted into the grommet by compressing the spring. Once installed in the grom- met the stud assembly cannot be removed unless the spring is again compressed.

The grommet is a flanged sheet metal ring made to fit into a hole in the access door or panel. ft is ribbed and can be pressed or dimpled into place.

The receptacle consists of a metal forging mounted


Figure 29. Camlock fastener.

in a stamped sheet metal. It is riveted to the access opening frame attached to the structure or equip- ment.

A quarter turn clockwise of the stud screw locks the cross pin into the grooved receptacle. Con- versely, a counterclockwise rotation releases the con- nection between the stud assembly and the reeep tacle.

Dzus FASTENERS. The Dzus fastener (Fig. 30) eon- sists of a rotatable stud, which may have a slot for a screwdriver or a winged fitting on it for hand oper- ation. It also has a permanently mounted spring and a grommet. The stud and grommet are mounted in the door or other removable part, and the spring is riveted to the frame of the access on which the door fits.

Cams on the stud engage with the spring to lock the fastener in the engaged position. The purpose of the grommet is to retain the stud in the access door. In some installations, the grommet is not used as a

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Figure 30. Dm fastener.

retainer; the stud is secured to the access door by a snapring, cup washer, or bv dimpling of the metal around the stud.

The quick action of the Dzns fastener is achieved when a quarter tmn rotation of the stud causes its engagement or disengagement with the spring.

Safetying Methods

Safetying is a process of securing fasteners and other equipment so they do not work loose due to vibration. Loose bolts, screws, and nuts or other parts can ruin delicate equipment or endanger life when they fall off equipment.

Various methods for safetying parts exist. The most widely used are safec! wire and cotter pins. Be sure to learn the proper techniques and use them.

Safety Wiring

Safety wiring is the most positive and satisfactory method of safetying capscrews, studs, nuts, and bolt heads which cannot be safetied by any other prac- tical means. It is a method of wiring together two or more units in such a manner that any tendency of one to loosen is countered by the tightening of the

wire and the other unit. Components are safety wired by the single wire plain method or the twist method (Fig. 31).

The single wire plain method may be used on small components in a closely spaced, closed geo- metrical pattern, and in places that are difhcult to reach. When safety wiring closely spaced com- ponents, take advantage and safety wire the whole series. The number of parts in the series safely wired together by this method depends upon the application; but the maximum number in the series is limited by a maximum 24 inch wire length.

The twist method is the most common method of safety wiring. The technique is shown in Fig. 32. A group of three should be the maximum in the series when safety wiring widely spaced components by this method.

The following general rules should be followed when using the safety wire method to secure com- ponents.

I. The safety wire must be new upon each appli- cation.

2. All safety wires must be tight after instalIation, but not under such tension that normal handling or vibration will break the wire.

3. The wire must be applied so that all pull exerted by the wire tends to tighten the nut.

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Figure 33. Types of cotter pins


Figure 31. Safety wiring methods.

4. Twists should be tight and even and the wire between the nuts as taut as possible without over- twisting. Wire twister pliers should be used if avail- able; otherwise, wire between nuts should be twisted with the hands. The use of regular pliers for twisting will damage the wire. Regular pliers may be used only for the final twist, prior to cutting off the excess wire.

5. When castellated nuts are to be secured, tighten the nut to the low side of the selected torque range, unless otherwise specified and, if necessary, continue tightening until a slot aligns with a hole.

COTITZI PINS. Some cotter pins are made of low- carbon steel, while others consist of stainless steel


Figure 34. Cotter pin instdation.

and thus are more resistant to corrosion. Regardless of shape or material, all cotter pins are used for the same general purpose-safetying.

Dimension perimeters of a cotter pin are shown in Fig. 33. Whenever uneven prong cotter pins are used, the length measurement is to the end of the shortest prong.

A cotter pin imtallation is shown in Fig. 34. The cotter pin should fit neatly into the hole with very little sideplay.

In the preferred installation method, the bent prong above the bolt end should not extend beyond the bolt diameter. Additionally, the bent prong should not rest against the surface of the washer. Cut the prongs down to size if necessary.

If the optional wraparound method is used, the prongs should not extend outward, but should be bent over a reasonable radius to the sides of the nut. Sharp-angled bends invite breakage. Usually the initial bending of the prongs of a cotter pin is ac- complished with needle nose or diagonal pliers and the best tool for final bending of the prongs is a soft faced mallet.

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Figure 32. Standard twist safety wire installation procedure.

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Chapter 9

Metal Spinning

Spinning is one of the oldest of the metal-working arts and has been used in making circular metal ware for many years. Although in recent years it has been largely replaced by draw press forming for large scale production, it is still widely 1 :ed for forming limited quantities when tool costs must be kept low, as well as in the manufacture of products which cannot be formed on a draw press because of size or complicated design. Spinning is also commonly used in combination with drawing for economy in finish- ing and trimming operations.

In the spinning process, a lathe similar to the type shown in Fig. 1 is used to rotate a circular metal blank or shell at high speed while it is pressed against a rotating chuck whose shape the metal blank being formed is to take. The blank is forced against the chuck by means of suitable forming tools, which are manipulated either by hand or mechanically (Fig. 2). With an experienced operator, spun articles can be held to reasonably close dimensional accuracy and will be uniform in size and identical in appear- an-.x?.

Since the metal is formed over a chuck rotating in a lathe, the process is limited to symmetrical articles that are circular in cross section, normal to the axis of rotation. Typical spun articles are cooking utensils, lighting reflectors, processing kettles, and ornaments of many d&rent types made of silver, aluminum, copper, pewter, and similar metals.

The Lathe for Metal spinning

The first requirement of the lathe for spinning is a substantial headstock spindle. Suitable bearings must be provided to take up the heavy end and lat- eral thrusts. There must be absolutely no end play. The speed range should be between 999 and 1499 ‘pm for average work. Speeds somewhat lower than this are useful but not necessary. A speed range

above 1499 rpm is useful for polishing and finishing operations, but is seldom necessary for actual spin- ning. The power unit should preferably be a ih hp motor, a!tbough a wide range of light spinning can be done with an even less-powerful motor.

TOOIS. There are many shapes of spinning tools, and the more or less standardized types used are shown in Fig. 3.

The beading tool is a specialized type used to turn the rim of the disk into a lip or a true bead. It is also useful to start bending the metal where the edge is to be folded to a double thickness. The pulley, which rotates freely within the holder, is interchangeable with other sizes to suit a wide variety of work.

The fit tool is the most important tool in the metal-spinner’s kit. It is double-surfaced; round on one side and flat on the other. The round side is used to ‘break down” the metal blank almost to the chuck surface, and the flat side completes the operation of smoothing the metal snugly to the chuck.

The point tool is both a forming and finishing tool that is particularly useful on small work. Its pointed end surface is useful in shaping fillet corners or forming sharp internal bends in the metal surface.

The cutting-@ tool, parting tool, or gmver, is simply what its name implies-a tool for cutting. It is used to trim away surplus metal at the neck of the spinning; also, it makes an excelhmt tool for scraping down high spots on the metal.

The ball tool is used to break down the surface of hard metals. It is not a finishing tool and should not be used to bring the metal snug to the chuck sur- face,

The back stick is an auxiliary aid to the various spinning tools. Its purpose is to back up the metal on one side as the pressure of the spinning tool is brought to bear on the opposite side. The stick should be made from hard wood, either rectangular


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or round in section, and should have a blunt point similar to a chisel.

All spinning tools should be properly tempered and then polished to reduce friction. The overall length of each tool should be about 2 ft., in order to give the required leverage necessary for spinning.

THE TOOL Rmr (Fig. 3). The tool rest or support for the spinning tools is a peg or fulcrum type of tee rest. It should have a shank to fit the tool-support base. The tool rest is drilled with a number of holes, as shown, to permit various settings of the fulcrum pin to suit the work.

TAILSTOCK CENTER (Fig. 3). The tailstock center for metal spinning must revolve with the work. Three different types are shown in the illustration.




Figure 2.

Each features a txpered shank which fits the tail- stock Spindle. This portion of the center is fixed. The rotating center is housed within the fixed body, and is given a free movement by some form ot ball- bearing. A good spinning crntcr is essential.

Aasoas ANU FACEPLAWS (Fig. 3). .\letal spinning is faceplate work, the wood or metal form or chuck over which the metal is spun being fastened to a suitable plate or arbor. A 9 in. f:rceplate with screw- fastenings into the chuck can be used, but the threaded nose type faceplate offers a quicker and more substantial form of mounting for this partic- ular work. The threaded nose can be either straight or tapered. Str,!ight and tapered screw arbors are also used extensively, especially for small work.

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Spinning Procedures 1net;11 blank while adding to thr st&lity of tllc, fill-

SICITINC-III’ ( Fig. 4). Any spinniq dtvn;mds ( 1 ) ;I ishd spi~u~i~~~. Figure 4, 1C shows thr &t;tl bl:wk

cb~~ck, (2) a follow block, (3) the metal bl:tuk. for this lxwticwl;u- spinning. III :dl mct;J spina~~irqr,

Fig”w 4, I.4 shows a typical simplr projx--;I ~!UIIIIW the radius of thr blank should be quat to thv r;wJi~~s

tray. A wwtl chwk mlist bc IIKI& IS,> to the exact of tiw project plus the depth of the project. The

sl:;qw of the p~opw.l objrct, wing :uny good-~~~dr blank should form n perfect circle with a smooth

ii;~l-c!:~~~d. It is gwd pwctu ‘0 ’ to tiii-il tllr ChlICk ill, edge all aroLllld,

incii 01’ so longer tiiai: the p~~qx~sc’d spilrnitl~. so Figure 5 shows othrr represrntative forms of sh:d-

that thwc will bc some space bc:twwc tbc firlislrrd law chucks IX fwns. Figwe 5, 9 shr~s a dq form,

spinning and thla fncepletr. The follow block or fol- SIIch as wtnlltl be required for :I metal cup. It is evi-

II~WI. is ww turnrd to shqw, eithtv on a sqxwatr dwlt that the deqwr form is more difficult to spin

fwqhtc. 01‘ by simply grippin:; it btWw~ll tb<, v11wk thw the shallow form since the: metui must be drawn

iiwl thi, s*Gin1: wnter. It should be at Icwt I in. to a grwter cxtwt. A series of chwks is somctinws

tllick, av~l of :I di;mwtrr from l;i to 1; in. 1~s tlwl cnq~lwed in spinning deep forms, as showy ill Fig.

tht, 1);~ di;uwtrr of tbr ptwjcct. as shower in Fig. 4. 5. 4. tilt3 metnl brink successively ?:pun OVCI‘ tbrrt. 0r

I 13. ‘1’11~ drawing sh~rws the h;w of tbc cbwk slightI\ hi- diffrwnt shapes qaduidly to result it> the fiil- COIIC’~I~C! imd the Ed of the* followt~~- sli~btly wnw5. ishctl form. T!w pwposc is to afiord a positive sup- This f0~1 of shapitq d~0dti be f~llowctl ~I~WWI port for the metal througho~~t thr V;U+OUS st;tges of







Figure 3.

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AII WOCI chocks should be glazed with soap or beeswnz (Fig. 5, 5). This is done after sanding, the soap or wax being forced into the pores of the \wxld with the Ant tool whiie the chuck is revolving;.

CEXTEHIXG The final operation before spinning is tt) center the metal blank. Where a hole in the center of the spinning is permissible. t!w blank can be h-

tened directly to the chuck (Fig. 3, 6). lo anothel n,d,c,d, ;m kImtat;on is made in the center of the blank. the indentation fitting over a round-head nail drirtv in the center of the chrxk (Fig. 5, 7 ). This readilv Iocotrs the center of the blank, after which the f&w block is brought np firmly to clamp the disk in place. In the ordinary method of centering, the disk is inserted between the chuck and follower, ccntcl-ing as closely as possible by eye. The tailstock is n1t1 forward to clamp the blank firmly but not too tightlv ilr place. The lathe is then started on low speed. sod the back stick is placed on the rest, to the left of the fulcrum pin (Fig. 1). The tailstock is then backed off slightly, and the stick advanced to touch the edge of the revolving disk. If the edge of the blank is smooth, the disk will center itself per- fectly, after which the follower is again set firmly against the metal. After the disk is centered, lubri- cate the metal on each side with laundry soap. The disk is now ready to spin.

SPDGNING THE METAL. Spinning the metal over the wooden form is not at all difficult, providing a few hard and fast rules are observed. The work canoot be hurried. Practically all craftsmen realize that it takes time to finish a wood or metal turning, yet some think that a similar operation in spun metal can be done in a few minutes. The beginner should keep this important point in mind.

The first operation in actual spinning calls for the flat tool. This is placed on the rest, to the left of the fulcrum pin, the pin being placed in the hole, which will set it slightly to the right of the metal blank. Now, with one or two sweeping strokes of the flat tool (the rounded edge contacts the metal), the disk is “seated” against the base of the chock. The back stick is now brought into play, holding up the metal on one side while the flat tool presses against the opposite side. The general position of the operator at this point can be see= in Fig. 2. The tool contacts the work well below center, as can be seen in Fig. 2. Notice, also, in this illustration, that there is a fairly wide gap between the metal disk and the tool rest. Figure 2 shows the same tool position as viewed

rz 3/4”7







Figure 4i.

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,, ,,








Figure 5.

from the front. Note how the fulcrum pin is located so that the tool can bear against the disk without tl;ti point digging into the metal. The back stick follows the point of the tool, leading it slightly.

The forming action of the tool becomes readily apparent when attempting actual work. The object is to force the metal around the chuck, and to do this the tool is simply brought to bear, with consid- erable pressure, against the revolving metal surface. The tool must not remain in any one spot because of the liability of burning right through the metal. lnstcad a sweeping action of the tool takes place, the tool moving constantly from the center to the rim of the disk. T!:is movement is effected by a “hunching” movement of the shoulders, the body of the operator moving to the right. Since the action is quite natural, there is little difficulty encountered on this score.

Various points essential to good spinning are shown in Fig. 6. At A is shown the initial operation,





Figure 6.

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the flat tool pressing against the disk while the back stick supports the opposite side. The closer the tool is to the chuck, as in C, the less need there is for the support of the back stick; the farther the tool from the chuck, as at B, the more necessary it be- comet to properly “back up” the metal. The first stage of the spinning brings the metal to the shape shown at B. The metal should be kept straight, like a shallow funnel, and should not be allowed to bell out, as shown at D. After the position shown at B has been attained, the flat tool alone can be used to force a small portion af the metal closer to the chuck surface, as shown at C. This action should not be too prulonged or over too much territory, either of which will result in the rim of the disk turning out, as shown at D. As soon as the rim begins to bell, the bock stick should be used and the metal again spun to a true funnel shape, as shown at E. Note that the funnel-shape is much sharper than shown at B. These




Figure 7.

two essential operations-crowding a small portion of the metal to the chuck surface and keeping the rest of the disk funnel-shaped-are carried out in successive operations, until the whole shape has been made.

F, Figure 6 illustrates a point which can only be learned completely from experience. It can be seen that the constant stroking of the tool towards the left has a tendency to thin the spun portion of the metal. If carried to extremes, the metal will burn com- pletely through. To avoid this, the stroking action of the tool must be reversed, stroking in the direction


Figure 8.


Figure 9.


Figure 10.

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show] by the RI’I’OWS ill G, Fig. 6 to How the metal the rim to bell out, and later attempts to spin it back back to ~~ormnl thickness. This opelatiou is especially to a true fuonel-shape r~sually result in a buckled itnportmrt where the metal is to be spun ;rn~md any edge instead of a smooth metal edge. sharp bend. Buckling, a commot~ difficulty iu spin- ning, is shown at H. Buckling is caused lnrgely by CUTTING-OFF. Figures 7 through 10 show oper+ forcing the work. That is, in attempting lo get an tions in trimming of% the surplus metal ns perfor~nrd immediate finished shape, the operator will press th* with the hand cut-off tool and with the slide rest. III work hard at the position shown nt D. This clauses either case, the point of the tool should be 011 center.



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BE-. The trimmed edge of the metal is fre- immediate use of a follow block. Instead, a starting quently turned over to form a bead. This operation chuck must be made up (A, Fig. 12). This has a re- is performed with the beading tool. As shown in Fig. cessed rim to take the metal blank snugly, while the 11, the point of the flat tool is first used to lift a center portion is turned out to the same spherical small m&ion of the metal from the chuck surface. shape as the intended finishei spinning. The metal The b&ding tool is then used to Work the metal into is s&n into this recessed center p&ion (B, Fig. 12), a true bead. the recessed rim holding the blank quite firmly. The

lhing special spinning c.hcks partly-formed disk can then be placed over the reg- alar chuck (C, Fig. 12) for finishing. Note that the

SPINNING A SPHERE. The spinning of a sphere dif- follow block is concave, so that it will fit snugly fers somewhat from work previously described, the against the metal. If the spinning is to be a perfect essential difference resting in the fact that the curved ball, two hemispheres must be made up and then surface of the spherical chuck does not permit the soldered together. (Soldering procedures are given




Figure 12.

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in Chap. 6.) The joint can be butted and buffed smooth after soldering (D, Fig. 12), or a very slight

SECTIONAL CHUCKS. Any form having a neck or

rim can be cut on one portion of the ball (E, Fig. opening smaller in diameter than some other portion

12), as an aid in m.aking the joint. of the work (Fig. 13) must be spun on a sectional

In a similar manner, any other spinning with either chock. The sectional chuck, as its name implies, is

a round or pointed end surface must be started by a built-up form, so arranged that the various pieces

first using a concave starting chuck. Where the end can be removed one by one from the inside of the

Cunrature is very slight, the follower can sometimes finished work. The typical example shown covers, in a general manner, the basic roles that must be ob-

be forced against the metal to give su5cient traction for spinning the metal (F, Fig. 12).

served in the making of any simple sectional chock. A starting chuck is always used in connection with





7 : = = : z - 6 : = =L

-_--_ : -T

0 e-.__- L -

: - 1 Z - Y








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the sectional chuck, the metal being spun over this and then switched to the built-up form. As far as it goes, which is to the widest part (A, Fig. 13) of the proposed project, the shape of the starting chuck must be identical with the shape of the sectional chuck. The sectional chuck itself consists of a main body, which carries the shape from the mouth of the project to its narrowest part (B, Fig. 13). At this point, the main body is reduced to a cylindrical core having a diameter from !& to 31 in. less than the smallest diameter of the project. Around this core are grouped the various segments, all of which are wedge-shaped, with the exception of the key piece, which is straight sided. The annular groove in the main body of the chuck takes a corresponding rim tamed on the segment portion.

In making a sectional chock, the main body is turned first (C, Fig. 13). The segment portion, in a solid block, is then rough turned to approximate di- mensions. .4 s; in. hole is drilled through the center. The turning is then removed from the lathe for the cutting of the various segments. These range in num- ber from 6 to 12 pieces, depending upon the size of the opening through which they must be withdrawn. The saw cuts are then sanded smooth and the seg- ments glued back in their original position, using glazed paper at the joints. The turning is then fin-

ished to exact size, carrying out the shape of the project externally and fitting the main body of the chuck internally. After sanding and glazing, the var- ious segments are again separated.

Spinning over a sectional chuck is carried out in much the same manner as spinning over a one-piece chuck. B, Figure 13 shows the initial shaping over the starting chuck. After this is finished, the sec- tional chuck main body is mounted in place, with the segments held in place by hand (C, Fig. 13). It is apparent that the partly-formed spinning will hold the segments securely in place, so that the rest of the shape can be formed (Fig. 13). After the spin- ning is completed, it can be slipped bodily from the main body of the sectional chuck, after which the key piece and then the other segments can be with- drawn (D, Fig. 13).

For average work, the gluing of the sectional chuck can be dispensed with by turning the segment portion to finished size and then sawing it apart with a very fine scroll saw or band saw blade. By allowing a little for the various saw kerfs, a sufficiently accu- rate form can be made in this manner. If the chrmk is to be made in metal, the same general procedure as first described is followed, sweating the segments together with solder.

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,, ,,‘,~ ,, ,~,

Chapter 1

ortable Metalworking Power Tools

With the machines and power tools available to- day, hand operations are practically eliminated in ordinary jobs. Such work is generally performed only to correct errors or where proper power tools are not available. This chapter will be devoted to the more common types of portable electric and air- driven power tools and equipment.

Portable Electric Power Tools

Portable power tools are tools that can be moved from place to place. Some of the most common port- able power tools used are drills, disc sander, grinders, saber saw, and impact wrench.


The portable electric drill (Fig. 1) is probably the most frequently used power tool. Although it is es- pecially designed for drilling holes, by adding vari- ous accessories it can be adapted for different jobs. Sanding, sawing, huffing, polishing, screw-driving, wire brushing, and paint mixing are examples of possible uses.

Portable electric drills commonly used have ca- pacities for drilling holes in steel from l/18 inch up


Figure 1. % inch portable electric drill.

to 1 inch in diameter. The sizes of portable electric drills are classified by the maximum size straight shank drill they will hold. That is, a l/4 inch electric drill -will hold a straight shank drill up to and in- cluding l/4 inch.

The revolutions per minute (rpm) and power the drill will deliver are most important when choosing a drill for a job. You will find that the speed of the drill motor decreases with an increase in size, pri- marily because the larger units are designed to turn larger cutting tools or to drill in heavy materials, and both these factors require slower speed.

If you are going to do heavy work, such as drilling in masonry or steel, then you would probably need to use a drill with a 3/8 or l/2 inch capacity. If most of your drilling will he forming boles in wood or small holes in sheet metal, then a l/4-inch drill will probably be adequate.

The chuck is the clamping device into which the drill is inserted. Nearly all electric drills are equipped with a three-jaw chuck. Some of the drill motors have a hand-type chuck that you tighten or loosen by band, but most of the drills have gear-type, three-jaw chucks which are tightened and loosened by means of.a chuck key (Fig. 2). Do not apply further pres- sure with pliers or wrenches after you hand-tighten the chuck with the chuck key.

Always remove the key immediately after you use it. Otherwise the key will fly ioose when the drill motor is started and may cause serious injury to you. The chuck key is generally taped on the cord of the drill; if it is not make.sure you put it in a safe place where it will not get lost.

Portable electric drills have controls similar to the ones shown on the l/4-inch drill in Fig. 1. This drill has a momentary contact trigger switch located in the handle. The switch is squeezed to start the electric drill and released to stop it.

The trigger latch is a button in the bottom of the


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Figure 2. Three-jaw chuck and chuck key.

drill handle. It is pushed in, while the switch trigger is held down, to lock the trigger switch in the ON position. The trigger latch is released by squeezing and then releasing the switch trigger.

: Sanders

Portable sanders are tools designed to hold and operate abrasives for sanding metals, plastics, and wood

‘Disc Sander

Electric disc mm&m (Fig. 3) are especially useful on work where a large amount of material is to be removed quickly, such as scaling surfaces in prep- aration for painting. This machine must not be used where a mirror-smooth finish is required.

The disc should be moved smoothly and lightly over the surface. Never allow the disc to stay in one place too long because it will cut into the metal and leave a large depression.



Figure 4. Portable grinder.

Portable Grinders

Portable grinders are power tools for rough grind- ing and finishing of metallic surfaces. They are made in several sizes (Fig. 4).

The abrasive wheels are easily replaceable so that different grain size and grades of abrasives can be used for varying types of surfaces to be ground and the different degrees of finish desired.

A flexible shaft attachment is available for most portable grinders. This shaft is attached by removing the grinding wheel, then attaching the shaft to the grinding wheel drive spindle. The grinding wheel can then be attached to the end of the flexible shaft. This attachment is invaluable for grinding surfaces in hard to reach places.

The wheel guard on the grinder should be po- sitioned so that abrasive dust and metal particles will be deflected away from your face.

Before you turn the grinder on, make sure the abrasive grinding wheel is properly secured to the grinder spindle and not cracked or damaged.

Figure 3. Disc sander.

Saber Sow

The saber saw (Fig. 5) is a power-driven jigsaw that will let you cut smooth and decorative curves in light metal and wood. Most saber saws are light duty machines and are not designed for extremely fast cutting.

There-are several different blades designed to oper- ate in the saber saw, and they are easily inter- changeable. A blade with fine teeth is designed for cutting metal. For fast cutting of wood, a blade with coarse teeth may be used.

The best way to learn how to handle this type of tool is to use it. Before trying to do a finished job

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Figure 5. Saber or bayonet saw operations.

width the saber saw, clamp down a piece of scrap plywood and draw some curved as well as straight lines to follow. You will develop your own way of gripping the tool, and this will be affected somewhat by the particular tool you are using. On some tools, for exam& you will find guiding easier if you apply some downward pressure on the tool as you move it forward. If you are not firm with your grip, the tool will tend to vibrate excessively and this will roughen the cut. Do not force the cutting faster than the de- sign of the blade allows or you will break the blade.

Electric Impact Wrench

The electric impact wrench (Fig. 6) is a portable hand-type reversible wrench. The wrench shown has a l/2-inch square impact driving anvil over which l/2-inch square drive sockets can be fitted. Wrenches also can be obtained that have impact driving anvils ranging from 3/8 to 1 inch. The driving anvils are not interchangeable from one wrench to another.

The electric wrench with its accompanying equip ment is primarily intended for applying and remov- ing nuts, bolts, and screws. It may also be used to drill and tap metal, plastic, wood, and the like, and drive and remove socket-head Phillips-head, or slotted-head wooed, machine, or self-tapping screws.

Before you use an electric impact wrench, depress the on-and-off trigger switch and allow the electric wrench to operate a few seconds, noting carefully the direction of rotation, Helease the trigger switch

to stop the wrench. Turn the reversing ring located nt the rear of the tool; it should move easily in one direction (which is determined by the current di- rection of rotation). Depress the oll-and-off trigger again to start the electric wrench. The direction of rotation should now be reversed. Continue to operate for a few seconds in each direction to be sure that the wrench and its reversible features are functioning correctly. When you are sure the wrench operates properly, place the suitable equipment on the im- pact driving anvil and go ahead with the job at hand.

Safety Precautioaa Safe practices in the use of power tools cannot be

overemphasized. There are several general safety measures to observe in operating or maintaining power equipment.

1. Never operate power equipment unless you are thoroughly familiar with its controls and operat- ing instructions or ask someone who knows.

2. All portable tools should be inspected before use to see that they are clean and in a proper state of repair.

3. Have ample illumination. If extension lights are required, ensure that a light guard is provided.

4. Before a power tool is connected to a source of power (electricity, air, and so on), be sure that the switch on the tool is in the OFF position.

5. When operating a power tool, give it your full and undivided attention.

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Figure 6. Reversible electic impact wench.

6. Keep all safety guards in position and use safety shields or goggles when necessary.

7. Fasten all loose sleeves and aprons. 8. Never try to clear jammed machinery unless

you remove the sotnce of power first. 9. After using a power tool, torn off the power,

remove the power source, wait for all rotation of the tool to stop, and then clean the tool. Remove all waste and scraps from the work area and stow the tool in its proper place.

10. Never plug the powei cord of a portable elec- tric tool into an electrical power source before en- su;iEg that the soxce has the voltage and rjipe of current (alternating or direct) called for on the nameplate of the tool.

11. If an extension cord is required, always con- nect the cord of a portable electric power tool into the extension cord before the extension cord is in- serted into a convenience outlet. Always unplug the extension cord from the receptacle before the cord of the portable power tool is unplugged from the ex- tension cord. (The extension cord and the power cord can each be no longer than 25 feet in letigth. Extra extension cords should be limited, wherever possible, to maintain allowable resistance to ground.)

Portable Pneumatic Power Tools

Portable pneumatic power tools are tools that look much the same as electric power tools but use the energy of compressed air instead of electricity. They are used most around a shop where compressed air outlets are readily accessible.

Pneumatic Chipping Hammer

The pneumatic chipping hammer (Fig. 7) con- sists basically of a steel piston wh,ich is reciprocated (moved backward and forward alternately) in a steel barrel by compressed air. On its forward stroke the piston strikes the end of the chisel, which is a sliding fit in a nozzle pressed into the barrel. The rearward stroke is cushioned by compressed air to prevent any metal-to-metal contact. Reciprocation of the piston is automatically controlled by a valve located on the rear end of the barrel. Located on the rear end of the barrel is a grip handle containing a throttle valve.

The throttle valve is actuated by a throttle lever which protrudes from the upper ear of the grip handle for thumb operation. Projecting from the butt of the handle is an air inlet. The handle is threaded

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Figure 7. Pneumatic chipping hammer.

onto the barrel and is prevented from unscrewing b) a locking ring. Surrounding and retaining the locking ring is an exhaust deflector. This deflector may be located in any of four positions around the barrel in order to throw the stream of exhaust air to the de- sired direction.

The pneumatic hammer may be used for beveling, calking, or beading operations, and for drilling in brick, concrete, and other masonry.

Chipping hammers should not be operated with- out safety goggles and all persons in the immediate vicinity of the work should wear goggles.

While working, never point the chipping hammer in such a direction that other people might be struck by an accidentally ejezted tool. When chipping alloy steel or doing other heavy work, it is helpful to dip

the tool in engine lubricating oil about every six inches of the cut and make sore the cutting edge of the tool is sharp and clean. This will allow faster and easier cutting and will reduce the possibilit! of the tool breaking.

When nearing the end of a cot, ease off on the throttle lever to reduce the intensity of the blows. This will avoid any possibility of the chip or tool flying.

If for any reason you have to lay the chipping hammer down, always remove the attachment tool from the nozzle. Should the chipping hammer be ac- cidentally started when the tool is free, the blow of the piston will drive the tool out of the nozzle with great force and may damage equipment or cause injury.

Fi@re 8. Needle impact scaler.

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Figure 9. Rotary impact SC&Z.

Needle and Rotary Impact Scalers

Needle and rotary scalers (Figs. 8 and 9 ) are used to remove rust, scale, and old paint from metallic and masonry surfaces. You must be especially careful when using these tools, since they will chew up any- thing in their path. Avoid getting the power line or any part of your body in their way.

Needle scalers accomplish their task with an as- sembly of individual needles impacting on a surface hundreds of times a minute. The advantage of using individual needles is that irregular surfaces can be cleaned readily.

The rotary sca!ing and chipping tool, sometimes called a jitterbug, has a bundle of cutters or chippers for scaling or chipping (Fig. 9). In use, the tool is pushed along the surface to be scaled and the ro- tating chippers do the work. Replacement bundles of cutters are available when the old ones are worn.

Portable Pneumatic Impact Wrench

The portable pneumtic impact wrench (Fig. 10) is designed for installing or removing nuts and bolts. The wrench comes in different sizes and is classified by the size of the square anvil on the drive end. The anvil is equipped with a socket lock which provides positive locking of the socket wrenches or attach- ments. The wrench has a built-in oil reservoir and an adjustable air valve regulator which adjusts the torque output of the wrench. The torque regulator reduces the possibility of shearing or damaging threads when installing nuts and bolts to their re- quired tension.

Nearly all pneumatic wrenches operate most effi- ciently on an air pressure range of from 80 to 90 pounds per square inch (p.s.i.). A variation in excess of plus or minus five pounds is serious, because lower pressure causes a decrease in the driving speeds, while higher pressure causes the wrench to overspeed, with subsequent abnormal wear of the motor impact mechanisms.

The throttle lever located at the rear of the pneu- matic wrench provides the means for starting and stopping the wrench. Depressing the throttle lever starts the wrench in operation. Upon release, the lever raises to its original position stopping the wrench.

The valve stem is seated beneath the pivot ends of the throttle lever. Most wrenches have a window cut in the throttle lever so that the markings on the upper surface of the valve stem will be visible. Two letters, F and R, have been engraved on the head of the valve stem to indicate the forward (clockwise) and reverse (counterclockwise) rotation of the anvil. To change from forward to reverse rotation, or vice versa, turn the vaive stem 180 degrees until the de- sired marking is visible through the window in the throttle lever. When the valve stem is in proper position, the valve stem pin engages a recess on the underside of the valve stem, preventing accidental turning oy the stem.

The air valve regulator is located at the bottom and toward the rear of the wrench. Using a screw- driver and altering the setting of the air regulator up to 90 degrees, either to the right or left, reduces the torque from full power to zero power.

Before operating the pneumatic impact wrench make sure the socket or other attachment you are

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Figure 10. Portable pneumetic impact wrench.

using is properly secured to the anvil. It is always a good idea to operate the wrench free of load in both forward and reverse directions. To see that it operates properly, check the installation of the air hose to make sure it is in accordance with the man- ufacturer’s recommendation.

Bench Grinder

The electric bench grinder (Fig. 11) is designed for hand grinding operations, such as sharpening &is& or screwdrivers, grinding drills, removing ex- cess metal from work, and smoothing metal surfaces. It is usually fitted with both a medium grain and fine grain abrasive wheel. The medium wheel is satisfactory for rough grinding where a considerable quantity of metal has to be removed, or where a smooth finish is not important. For sharpening tools or grinding to close limits of size, the fine wheel should be used, as it removes metal more slowly, gives the work a smooth finish, and does not gen- erate enough heat to anneal the cutting edges.

When a deep cut is to be taken on work or a con- siderable quantity of metal removed, it is often

practical to grind with the medium wheel first and finish up with the fine wheel. Most bench grinders are so made that wire brushes, polishing wheels, or buffing wheels can be substituted for the removable grinding wheels.

7’0 protect the operator during the grinding oper- ation an eyeshield and wheel guard are provided for each grinding wheel. A tool rest is provided in front of each wheel to rest and guide the work dur-


Figure 11. Bench grinder and wheel.

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ing the grinding procedure. The rests are removable, if necessary, for grinding odd-shaped or large work.

When starting a grinder, turn it on and stand to one side until the machine comes up to full speed. There is always a possibility that a wheel may fly to pieces when coming up to full speed. Never force work against a cold wheel; apply work gradually to give the wheel an opportunity to warm, thereby min- imizing the possibility of breakage.

Handle grinding wheels carefully. Before replacing a wheel always check it for cracks. Make sure that a fiber or rubber gasket is in place between each side of the wheel and its retaining washer. Tighten the spindle nut just enough to hold the wheel firmly. If the nut is tightened too much the clamping strain may damage the wheel. When selecting a replace- ment wheel, ascertain that the grinder will not ex- teed the manufacturer’s recommended speed for the wheel.

When grinding, always keep the work moving across the face of the wheel. Grinding against the same spot on the wheel will cause grooves to be ,worn into the face of the wheel. Keep all wheel guards tight and in place. Always keep the tool rest

‘, adjusted so that it just clears the wheel and is at or just below the center line of the wheel, to prevent

accidental jamming of work between tool rest and wheel.

Wear goggles, even if eyeshields are attached to the grinder. Keep your thumbs and fingers out of the wheel.

Safety Precautiona

In operating or maintaining air-driven tools, take the following precautionary measures to protect yourself and others from the damaging effects of compressed air.

1. Inspect the air hose for cracks or other defects. Replace the hose if found defective.

2. Before connecting an air hose to the com- pressed air outlet, open the control valve momen- tarily. Then, make sure the hose is clear of water and other foreign material by connecting it to the outlet and again opening the valve momentarily.

Caution: Before opening the control valve, see that nearby persons are not in the path of the air flow. Neoer point the hose at another person.

3. Stop the flow of air to a pneumatic tool by closing the control valve at the compressed air outlet before connecting, disconnecting, adjusting, or re- pairing a pneumatic tool.


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Chapter 11

Layout and Benchwork

Laying out is the method of placing lines on the stock to correspond to the lines and dimensions of the blueprint. These layouts are full size and must be measured and marked accurately on the stock. Limits and allowances must be observed.

Mechanical Drawings curd Blueprints

A mechanical &owing, made with special instm- ments and tools, gives a true representation of ac object to be made, including its shape, size, descrip- tion, specifications as to material to be used, and method of manufacture. A bheprht is an exact dup- licate of a mechanical drawing.

The following paragraphs cover briefly some im- portant points in connection with working from sketches and blueprints. Of the many types of blue- prints, the simplest one is the phn uiew. This is a blueprint which shows the position, location, and use of the various parts of the object.

In addition to plan views, you may use other blueprints, called assembly prints, unit or subassem- bly prints, and detail prints. These prints show var- ious kinds of machinery and mechanical equipment.

Assembly prints show the various parts of the mechanism and how the parts fit together. Individ- ual mechanisms, such as motors, pumps, and others, will be shown on subassembly prints. These show lo- cation, shape, size, and relationships of the parts of the subassembly unit. Assembly and subassembly prints are used to learn operation and maintenance of machines and equipment.

Detail prints give yw the information required to make a new part. They show size, shape, kind of ma- terial, and method of ilnishmg. You will find them indispensable in your work.

Working from Drawings

Detail prints usually show only the individual part

or piece you must produce. They show two or more orthographic views of the object, and, in special cases, they may show an isometric projection, with- out dimension lines, near the upper right corner. An isometric projection shows how the part will look when made.

Each drawing or blueprint carries a number, lo- cated in the upper left-hand corner and in the title box in the lower right-hand corner of the print. The title box also shows the part name, the scale used, the pattern number, the material required, the as- sembly or subassembly print number to which the part belongs, the job order number, the quantity and date of the order, and the names or initials of the persons who drew, checked, and approved the draw- ings.

Accurate and satisfactory fabrication of a part de- scribed on a drawing depends upon the following:

1. Correctly reading the drawing and closely ob- serving all data thereon;

2. Selecting the correct material; 3. Selecting the correct tools and instruments for

laying out the job; 4. Using the baseline or reference line method of

locating the dimensional points during layout, there- by avoiding cumulative errors (described later in this chapter);

5. Strict observance of tolerances and allowances; 8. Accurate gaging and measuring of work

throughout the fabricating process; 7. Giving due consideration, when measuring, for

expansion of the workpiece by heat generated by the cutting operations. This is especially important when checking dimensions during finishing operations, if work is being machined to close tolerance.

Accurate Measurement

It is to your advantage to always strive for the


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greatest amount of accuracy. You can work many hours on a project and if it is not accurate, you will often have to start over. With this thought m mind you would do well to study carefully the following information about both the English and metric sys-

terns of meesurement. EXCLSH SYSTEM. With the English system the

standard unit of measurement is the inch. The inch can be broken down into smaller par6 for finer measurements. One breakdown is the common frae- tion such as l/2 inch, l/4 inch, l/S inch, 1132 inch, or l/64 inch. The inch may also be divided into dec- imaI fractions, such as l/10, l/100, or l/1000. Dec- imal fractions can be expressed with a numerator and denominator. but in most machine shop work and on blueprints or drawings they are frequently expressed in decimal form such as 0.1 in., 0.01 in., and NO1 in. Decimal fractions are expressed in the following manner.

Qne-tenth inch = 0.1

One-hundredth inch = 0.01 One-thousandth inch = 0.001 Oniz ten-thousandth inch = o.ooo1

A breakdown from l/64 in. to 1 in. is shown in Table 26.

METRIC SYSTEM. The metric system is used by many countries other than the United States, and you should have an understanding of this system of measurement. The standard unit of measurement for the metric system is the meter.

In the metric system, the meter is subdivided into the following parts:

1 meter = 10 decimeters (dm) 1 decimeter = 10 centimeters (cm) 1 centimeter = 10 millimeters (mm)

From this we can say that one decimeter is one-tenth meter, one centimeter is one-hundredth meter, and one millimeter is one-thousandth meter. Other sub- divisions of the meter are also included in the metric system. One meter is equal to 2.54 centimeters.










































MiSi- Inem

keimsls of

m inch













1 64











Milli- metom

ccimab of

,n inch --


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greatest amount of accuracy. You can work many hours on a project and if it is not accurate, you will often have to start over. With this thought m mind you would do well to study carefully the following information about both the English and metric sys- terns of meesurement.

EXCLSH SYSTEM. With the English system the standard unit of measurement is the inch. The inch can be broken down into smaller parts for finer measurements. One breakdown is the common frae- tion such as l/2 inch, l/4 inch, l/S inch, 1132 inch, or l/64 inch. The inch may also be divided into dec- imaI fractions, such as l/10, l/100, or l/1000. Dec- imal fractions can be expressed with a numerator and denominator. but in most machine shop work and on blueprints or drawings they are frequently expressed in decimal form such as 0.1 in., 0.01 in., and 0.001 in. Decimal fractions are expressed in the following manner.

Qne-tenth inch = 0.1

One-hundredth inch = 0.01 One-thousandth inch = 0.001 One ten-thousandth inch = o.ooo1

A breakdown from l/64 in. to 1 in. is shown in Table 26.

Mrrrnrc SYSTEM. The metric system is used by many countries other than the United States, and you should have an understanding of this system of measurement. The standard unit of measurement for the metric system is the meter.

In the metric system, the meter is subdivided into the following parts:

1 meter = 10 decimeters (dm) 1 decimeter = 10 centimeters (cm) 1 centimeter = 10 millimeters (mm)

From this we can say that one decimeter is one-tenth meter, one centimeter is one-hundredth meter, and one millimeter is one-thousandth meter. Other sub- divisions of the meter are also included in the metric system. One meter is equal to 2.54 centimeters.










































MiSi- Inem

keimsls of

m inch













1 64











Milli- metom

ccimab of

,n inch --


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Lfrofk of Accuracy

You must work within the limits of accuracy spe c&d on the drawing. A clear understanding of t~l- emraze and alloc;~rrce will help you to avoid making small, hut potentially dangerous errors. These terms may seem closely related but each has a very precise meaning and application. The following paragraphs point out the meauiugs of these terms and the im- portance of observing the distincticms between them.

Tor.xa.u~cx. Working to the absolute or exact basic dimension is impracticable and uunecessary in most instances. The designer calcuIates, in addition to the basic dimensions, an allowable variation. The amount of variation or limit of error permissible is indicated on the drawing as a given amour& such as = 0.035; = I/W. The diffkrence between the allowable min- imum and the allowance n aximum dfmeusion is tol- erence. For example. in Fig. 1:


Basicdimension = 4 Long limit = 4 l/64 Short limit = 3 03/64 Tolerauce = l/32

When tolerances are not actually specilied on a +wing, fairly concrete assumptions can be made concerning the accuracy expected by llsing the fol- ln+ng principles. For diiensioas which end in a Lz ;&ion of an inch, such as US, l/16, l/32, 1164, I ,;sider the expected accuracy to be to the nearest l/34 inch. When the dimension is given in decimal form, the following applies.

If a dhnension is given as 3MlO in. the accuracy expected k 2 0.0005 in. or, ff the dimension is given as 3.00 in., the accuracy expected is & 0.005 in. The 2 0.0335 is plus or minus five ten-thousandths of an inch. The 2 0.003 is plus or minus five thousandths of an inch.

ALWW.~N~E. Aflowance is au intentional difference in dimensions of mating parts to provide the desired fit. A c&arance a&u~ncf? permits movement between mating parts when assembled. For example, when a hole with a 0.250 in. diameter ls fitted with a shaft that has a 0.245 in. diameter, the clearance allowance

is 0.005 in. An interference aUowance is the opposite of a clearance allowance. The difference in dimen- sions in this case provides a tight fit. Force is required when assembling parts which have an interference allowance. If a shaft with a 0.251 in. diameter is fitted in the hole identified in the preceding example, the difference between the dimensions will give an interference allowance of 0.001. As the shaft is larger than the hole, force is necessary to assemble the Parts.

What is the relationship between tolerance and allowance? In the manufacture of mating parts, the tolerance of each part must be controlled so that the parts will have the proper allowance when assem- bled. For example, if a hole 0.250 inch in diameter with a tolerance of 0.005 in. ( * 0.0025) is pre- scribed for a job, and a shaft to be fitted in the hole is to have a clearance allowance of 0.001 in., the hole must first be finished within the limits, and the re- quired size of the shaft determined exactly, before the shaft can be made. If the hole is finished to the upper limit of the basic dimension (0.!2525 in.), the shaft would be machined to 0.3515 in. or 0.001 in. smaller than the hole. If the dimension of the shaft was given with the same tolerance as the hole, it is obvious that there would be no control over the allowance between the parts. As much as 0.035 in. allowance (either clearance or interference) could result.

To provide a method of retaining the required allowance while permitting some tolerance in the di- mensions of the mating parts, the tolerance is limited to one direction on each part. This single direction (unilateral) tolerance stems from the basic hole sys- tem. If a clearance allowance is required between mating parts, the hole may be larger but not smaller than the basic dimension. The part that Pts into the opening may be smaller, but not larger than the basic dimension. Therefore, shafts and other parts that fit into a mating opening have a minus tolerance only. while the openings have a plus tolerance only. If an interference allowance between the mating parts is required the situation is reversed. The opeu- ing can be smaller but not larger than the basic dimension, while the shaft can be larger, but not smaller than the basic dimension. Therefore, you can expect to see a tolerance such as + .005, -0, or + 0, -.oaS, but with the required value not necessarily 335. One way to get a better understanding of a clearance allowance, or an interference allowance, is to make a rough sketch of the piece and add dimen- sions to the sketch where they apply.

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Be sure you have the correct print for the part to be made or repaired. You want the print which has not only the correct title, but also the correct assem- id! nomber.

Never take a measurement with a rule directly from the print because the tracing from which the print was made may not have been copied from the original drawing perfectly, and may contain scaling errors. .4bo, paper stretches and shrinks with changes in atmospheric conditious. Dimensions must be taken only from the figores shown ou the dimension lines.

Pe very careful in handhug alI blueprints and ~orkiug drawiuga. Wbeo they are not in use, place them on a shelf, in a c&met, or in a drawer. Return them to the blueprint He as soon as the job is done. blueprints and working drawings are always val- uable and often irreplaceable. Make it a point never to mutilate. destroy, or lose a blueprint.

Layout is the term used to describe the marking of metal surfaces that provides an outline for ma- chining. A layout is comparable to a single view (end, top, or side) or a part which is sketched di- rectly on the workpiece. The digiculty experienced ,‘h making layouts depeuds ou the intricacies of the, ,part to be laid out and the number of operations re- quired to make the part A Uange layout, for example, ts relatively simple, as the entire layout can be made on one surface of tbe blank tlange. However, an in- tricate casting may require layout lines on more than one surface. This requires careful study and concen- ,tration to ensure that the layout has the same rela- tiousbips as those shown on the drawing (or sample) that you are using.

When a part must be laid out on two or more surfaces, it may be necessary to lay out one or two surfaces and machine them to size before further layout lines can be used. This prevents removal of kiyout lines ou one surface while machining another. In other words, it would be useless to lay out the top surface of a part aud machine the layout lines off while cutting the part to the layout lines of an end surface.

Through the process of computing and transferring dimensions, you will become familiar with the rela- tionship of the surfaces. Understanding this relation- ship will be of be&t when planning the sequence of machtuiog operations.

Accuracy in making layouts depends on your ability. You should be capable of holding the dimen- sions of a layout to within a tolerance of l/64 in. Sometimes you must work to a tolerance of even less than that.

A layout of a part is made when the directional movement or location of the part is controlled by hand or aligned visually without the use of precision instruments (such as when the work is done on bandsaws or drill presses). When cutting irregular shapes on shapers, planers, lathes, or milling ma- chines, layout lines are made, and the tool or work is guided by hand. When making a part with hand cutting tools, layout is essential.

Mechanical drawing and layout are closely related subjects. Knowledge of one will help you understand the other.

MATE~AIS AND EQUIPMENT. A scribed line on the surface of metal is usually hard to see; therefore a layout liquid is used to provide a contrasting back- ground. Commercially prepared layout dyes or inks are available. Chalk can be used occasionally, al- though it does not stick to a finished surface as well as does layout dye. The layout dyes, commonly used, color the metal surface with a blue or copper tint. A line scribed on this colored surface reveals the color of the metal through the background.

The tools generally used for making layout lines are the combination square set, machinist’s square, surface gage, scriber, straightedge, rule, divider, and caliper. Tools land equipment used in setting up the part to be laid out are surface plates, parallel blocks, angle plates, V-blocks, and sine bar. Surface plates have very accurately scraped flat surfaces. They are used to provide a mounting table for. the work to be laid out so that all lines in the layout can be made to one reference surface. Angle plates are commonly used when the lines in the layout are at an angle to the reference surface. These plates may be fixed or adjustable. Fixed angle plates are considered to be more accurate because one surface is machined to a specific angle in relation to the base. Adjustable angle piates are convenient to use because the an- gular mounting surface may be adjusted to meet the requirements of the job. V-blocks are used for mount- ing round stock on the surface plate. Parallel blocks are placed under the work to locate the work at a convenient height.

The sine bar is a precision tool used for deter- mining angles which require accuracy within five minutes of arc. The sine bar may be used to check angles or establish angles for layout and inspection

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work. The sine bar must be used in conjunction with a surface plate and gage blocks if accuracy is to be maintained. Using the sine bar will be covered later in this chapter. (See also Chap. 2, Measuring Tools and How to Use Them.)

Layout Methods

To ensure complete accuracy when making lay outs, establish a reference point or line on the work. This line, called the baseline, is located so that it can be used as a base from which you can measure dimensions, angles, and lines of the layout. .4 machined edge or centerline may be nsed as a ref- erence line. Circular layouts, such as flanges, are usually laid out from a center point and a diameter line.

Inaccuracy in layouts can be held to a minimum when the reference method is used, because errors can be made only between the reference line and one specific line or point. Making a layout with each line or point referenced to the preceding one causes compounding of any existing error and thus results in an inaccurate layout.

Making a layout on stock that has one or more machine finished surfaces is usually easy. Laying out a casting presents special problems because the sur- fazes are too rough and not true enough to permit the use of squares, surface plates, or other mounting methods with any degree of accuracy. A casting usu- ally must be machined on all surfaces. Sufficient ma- terial must be left outside the layout line to permit truing ur ‘!e surface by machining. For example, a casting might have only l/8 inch machining allow- ance on each surface (or a total of l/4 inch over- size). It is obvious in this example that taking more than l/8 inch off any surface can mean the loss of the casting. The layout procedure is especially im- portant when there are irregular surfaces or cored holes in the casting. The layout lines then must be within the machining allowance on all surfaces. Do not attempt to make the layout so that a maximum amouflt of material is removed from one surface and a minimum amount from another surface.

MAKING LAYOUT LLNES. The following information is applicable to practically all layouts. Layout lines are formed by using a reference edge or point on the stock or by using the surface plate as a base.

LINES SQUARE OR PARAL~L TO EDGES. When scrib- ing layout lines on sheet metal, hold the scratch awl, or scriber, as shown in Fig. 2, leaning it toward the direction in which it will be moved and away from

Figure 2. Using a scribe.

the straightedge. This will help scribe a smooth line which will follow the edge of the straightedge, tem- plate, or pattern at its point of contact with the sur- face of the metal.

To square a line on stock with a combination square, place the squaring head on the edge of the stock (Fig. 3). Draw the line along either edge of the blade. The line will be square with the edge of the stock against which the squaring bead is held, that is, the angle between the line and the edge will be 90 degrees.

Figure 3. Using a combination square.

To draw lines parallel to an edge using a com- bination square, extend the bla.de from the squaring head the required distance, such as the Z-inch setting showu in Fig. 4. Secure the blade at this position. Scribe a line parallel to the edge of the stock by holding the scratch awl or scriber at the end of the blade as you move the square along the edge. All lines so scribed with diEerent blade settings will be parallel to the edge of the stock and parallel to each other.

To scribe a line parallel to an edge with a her- maphrodite caliper, hold the caliper as shown in Fig. 5, so that the curved leg maintains contact with the edge while the other leg scribes the line. Hold the

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Figure 6. Laying out a 4%degree angle.

Figure 4. Laying out parallel lines with a combination square.

Figure 7. Laying out angillar lines.

Figure 5. Laying out a parallel line with a hermaphrodite.

caliper in such a way that the line Will be scribed at the desired distance from the edge of the stock.

FORMING ANGULAR LINES. To lay out a 45 degree angle on stock, using a combination square, place the squaring head on the edge of the stock as shown in Fig. 6, and draw the line along either edge of the blade. The line will form a 45 degree angle with the edge of the stock against which the squaring head is held.

on the surface. Scribe the lines along the .edge of the blade on the work. The angle set on the scale deter- mines the angle laid out on the work. All lines drawn with the same setting, and from the same true edge of the work, will be parallel lines.


To draw angular lines with the protractor herd of a combiilation square, loosen the adjusting screw and rotate the blade to where the desired angle lines up with the index mark on the body of the protractor head. The setting shown in Fig. 7 is 60 degrees. Tighten the screw to hold the setting.

Hold the body of the protractor head in contact with a true edge of the work with the blade resting

or segments of circles are laid out from a center point. To ensure accuracy, the center point is prick punched to keep the point of the dividers from slip- ping ant of position. Use the center head and rule, aS shown in Fig. 8, to locate the center of round stock. To find the center of square and rectangular shapes, scribe straight lines from opposite corners of the workpiece: The intersection of the lines lo-

cates the center. To lay out a circle with a divider, take the setting

of the desired radius from the rule, as shown in Fig. 9. Note that the 3 inch setting is being taken away from the end of the rule. This reduces the chance of

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Figure 8. Using a center head and mle.

Figure 9. Setting a ditider to a dimension.

error as each point of the dividers can be set on a graduation. Place one leg of the divider at the center of the proposed circle, lean the tool in the direction it will be rotated, and rotate it by rolling the knurled handle between your thumb and index finger (A, Fig. 10).

When setting trammel points (B, Fig. lo), follow the same direction as for a divider; a steel tape may be required to set the trammel points.

To lay out a circle with trammel points, hold one point at the center, lean the tool in the direction you propose to move the other point, and swing the arc or circle (B, Fig. 10).

To transfer a distance measurement with trammel points, hold one point as you would for laying out a circle and swing a small arc with the other point opened to the desired distance.

Scribing an irregular line to a surface is a skill used in fitting a piece of stock (Fig. 11) to a curved surface. A, Fig. 11 shaws the complete fit. in ii, Fig. 11, the divider has scribed a line from left to right. When scribing horizontal lines, the legs of the divider must he kept plumb (one above the other). When scribing vertical lines, the legs must be kept level. To scribe a line to an irregular surface, set the di-

Figure 10. Laying Out circles.

A 6

Figure 11. Laying out an irregular line from a surface.

vider so that one leg will follow the irregular surface and the other leg will scribe a iine on the materiai that is being fitted to the irregular surface (B, Fig. 11).

USING THE SURFACE PLAY. The surface plate is used with such tools as parallel squares, V-blocks, s-urface gages, angle plates, and sine bar in making layout lines. Angle plates similar to the one shown in Fig. 12 are used to mount work at an angle on the surface plate. The angle of the angle plate is set by using a protractor and rule of the combination square set, or by using a vernier protractor.

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plate. Move the surface gage into position. Set the scriber to the approximate height required, using the adjusting clamp that holds the scriber onto the spin- dle. Make the final adjustment for the exact height required (4 l/2 inches in this example) with the ad- justing screw nr the base of the surface gage.

UsrNo THE NF BAR. The sine bar is used in con- junction with the surface plate. The sine bar is not used as often as other layout tools, but it would be advantageous to know how to use the sine bar. Sine bars, such as the one shown in Fig. 14, are available in various sizes with lengths of 5 in., 10 in., and 20 in. The length is taken from the center line of the rolls. To be able to use the sine bar, you must be familiar with natural trigonometric functions. In Fig. 14 we have a desired angle A, and to achieve this angle we must find dimension X. This is done in fhe following manner. Dimension X = length of sine bar times the sine of angle.

Example: Length of sine bar = 5 in. Angle A = 23 degrees 35 ft. Sine of angle A = 0.4000 x = 5 x 0.40008 X = 2.00040 in.

By reversing the procedure you can find the angle. The formula for finding the angle is as follows.

Distance X Sine of angle =

Length of Sine Bar


sometimes necessary to scribe in a layout which can- not be made using conventional layout methods. For example, making straight and angu!ar layout lines on sheet metal with irregular edges cannot be done readily by using the combination square set. Neither can sheet metal be mounted on angle plates in a manner that permits scribing angular lines. Geo- metric construction is the answer to this problem.

Use a dioider to lay out a perpendicular from a point to a line, as shown in Fig. 15. Lightly prick


I- T-

Figure 12. hgle plate.

Figure 13. Setting and using a surface gage.

A, Fig. 13 shows the use of a surface gage V-block combination in laying out a piece of stock. To set a surface gage for height, 6rst clean the top of the surface plate and the bottom of the surface gage. Then place the squaring head of a combination square as shown in B, Fig. 13. Secure the scale so that the end is in contact with the surface of the

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Figure 15. Layout of a perpendicub from a point to a he.

Figure 1% Layout of a perpendiadar from a point on a line.

I /----r----N J E FG H

4 c D --i

Figme 17. Layout of a par&: Ihe.

Figure 18. Bisecting an angb.

punch the point, C, then swing any arc from C which will intersect the line AB, and prick punch the intersections D and E, as shown in the iSus- tration. With D and E as centers, scribe two arcs which intersect at a point such as F. Place a straight- edge on points C and F. The line drawn a!ong this straightedge from point C to line A3 will be per- pendicular (90 degrees) to the line AB.

Use a &older to lay out a perpendicular +nn a point on a line, as shown in Fig. 16. Lightly prick punch the point which is identified in the illustra- tion as C on line AB. Then set the divider to any dis- tance to scribe arcs which intersect AB at C and E with C as the center. Punch D and E lightly. With D and E used as centers, and with tbe setting of the divider increased somewhat, scribe arcs which cross at points such as F and 6. The line drawn through F and G will pass tbrougb point C and be perpen- dicuiar to line AB.

To lay out parallel lines with a divider, set the divider to the selected dimension. Then, referring to Fig. 17, from a:~y points prick punched such as C and D on line. From AB swing arcs EF and GH. Then draw line IJ tang&t to these two arcs, and it will be parallel to line AT! and at the selected dis- tance from it.

Bisetiin~ an at+ is another geometric construc- tion with which you should be familiar. Angle ABC (Fig. 18j is given. With B a? a center, draw an arc cutting the sides of the angle at D and E. With D and E as centers, and witb a radios greater than half of arc DE, draw arcs intersecting at F. A line drawn from B through the point F bisects the angle ABC.

Lw&-Ig out Valve Plange Bolt Holes

&fore describing the procedure for making val,ve flange layouts, it is best to clarify the terminology involved in the description that will ‘be given. Figure 19 shows a valve flange with the bolt holes marked on the bolt circle. The straight line distance between the centers of two adjacent holes is called the pitch &r-d. The bolt hcle circle itself is called the pi&h circk. The vertical !ine across the face of the flange is the oertical bisector, and the botizontal ji*zle across the face of the flange is the horizontal bisedor.

The bolt holes’ centers on the pitch circle and the pitch chord are equidistant. The p&b. chord be- tween any two adjacent holes is exactly the same as the pitch chord between any other twc adjacent holes. No& that the two top holes and the two hot- tom holes straddle the vertical bisector. The vertica: bisector cuts the pitch chord for each pair exa.ctIy in half. This is the standard method of placing the holes for a 6-hole flange. In the 4-, 8-, or I%-h,ole flange, the bolt holes straddle both the vertical and hori- zontal bisectors. This system of bole p!acement per- mits a valve to be installed in a hue vertical 07 horizontal position, provided that the pipe fiange holes are also in standard location on the pitch cir-

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de. before proceeding with a valve flange layout job, find out d&nitely whether the holes are to be placed in standard position. If you are working on a per sumple job, follow the layout of the sample. The pro- cedure for setting up the layout for straight globe or gate valves is as follows.

1. Fit a fine grain wood plug in the opening in each flange (Fig. 19). The plug should fit snugly and be Bush with the face of the flange.

2. Apply layout dye to the flange faces, or if dye is not available, rub chalk on the flange faces to facilitate the drawing of lines which will be clearly visible.

3. Locate the center of each flange with a sxface gage, or with a center head and rule combination, if the flange diameter is relatively small. (See Fig. 13 and A, Fig. 6.) After you have the exact center point located on each flange, mark the center with a sharp prick punch.

4. Scribe the pitch or bolt circle, using a pair of dividers. Check to see that the pitch circle and the outside edge of the flange are concentric.

5. Draw the vertical bisector. This line must pass through the center point of the flange and it must be visually located directly in line with the axis of the valve stem (Fig. 19).

6. Draw the horizontal bisector. This line must also pass through the center point of the flange and must be laid oJt at right angles to the vertical bi- sector. (See Figs. 16 and 19.)

Up to this point the layout is ihe same for all flanges regardless of the number of holes. Beyond



F&we 19. Flange layout tednology.

this point the layout differs with the number of holes. The layout for. a &hole flange is the simplest one.

SEX-How FLANGE. Set your dividers exactly to the dimension of the pitch circle radius. Place one leg of the dividers on the point where the horizontal bi- sector crosses the pitch circle on the right-hand side of the flange, point (1) in A, Fig. 20, and draw a small arc across the pitch circle at points (2) and (6). Next, place one leg of the dividers at the inter- section of the pitch circle and horizontal bisector on the left-hand side of the flange point (4), and draw a small arc across the pitch circle line at points (3) and (5). These points ( 1) to (6) are the centers

Figure 20. Development of a B-hole flange.

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Figure 21. Four-hole flange development. ’

for the holes. Check the accuracy of the pitch chords. To do this, leave the dividers set exactly as you had them set for drawing the arcs. Starting from the located center of any hole, step around the ci-cle with the dividers. Each pitch chord must be equal to the setting of the di*tiders. If it is not, you have an error in hole mark piacement that must be cor- rected before you can center punch the marks for the holes. After you are sure the layout is accurate, cen- ter pun& the hole marks and draw a circle of ap- propriate size around each center punched mark and prick punch witness mu&s around the circumfer- ence, as shown in B, Fig. 20. These witness marks will be cut exactly in half by the drill to verify a correctly located hole.

FOOUR-Hors F-GE. Figure 21 shows the develop- ment for a 4-hole flange layout. Set your dividers for slightly more than half the distance of arc AB, and

then scribe an intersecting arc across the pitch circle line from points A, B, C, and D, as shown in A, Fig. 21. Next, draw a short radial line through the point of intersection of each pair of arcs, as shown in B, Fig. 21. The points where these lines cross the pit& circle, (I), (Z), (3), and (4), are the centers for the holes. To check the layout for accuracy, set your divider for the pitch between any two adjacent boles and step around the pitch circle. If the holes are not evenly spaced, find your error and correct it. When the layout is correct, follow the center punching and witness marking procedure described previously under the 6-hole flange layout.

Erorrr-HOLE FLAVGE. Figure 22 shows the develop- ment of an g-hole placement. The procedure is as follows. First locate point E by the same method as described for locating point (1) in the 4-hole layout. Then divide the arc AE in half by the same method.

Figwe 22. Eight-hole flange development.

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The mid-point of arc AE is the location for the cen- ter of hole (I) (A, Fig. 22). Next set your dividers for distance A (l), and draw an arc across the pitch circle line from A at point (8) ; from B at points ( 2) and (3); from C at (4) and (5); and from D at (6) and (7) (B, Fig. 22). Now set your calipers for distance AE and gage the pitch chord for accuracy. Then finish the layout as described in the preceding paragraphs.

MATHEMAWXL D~XRMINATION OF PIZ@ CHORD LF.NGTH. In addition to the geometric solutions given in the preceding paragraphs, the spacing of valve flange bolt hole centers can be determined by sim- ple multiplication provided a constant value for the desired number of bait holes is known. The diam- eter of the pitch circle multiplied by the constant equals the length of the pitch chord. The constants for specified numbers of holes are given in Table 27.


No. bolt holes

5--------- 6--------m


0.666 .7011 .5879 i .5 .4338 .3821 .342 .309 .2617 .2588 .2394 .2225 .2079 .195 .184 .1736 .1645 .1564

Here is an example of the use of Table 27. Suppose a flange is to have 9 bolt holes, laid out on a pitch circle with a diameter of 10 inches. From the table, select the constant for a g-hole flange. The pitch diameter (10 inches) multiplied by the appropriate constant (.342) equals the Iength of the pitch chord (3.420 in&es). Set a pair of dividers to measure 3.420 inches, from point to point, and step off around the circumfeience of the pitch circle to locate the centers of the flange bolt holes. Note that the actual placement of the holes in relation to the vertical and

horizontal bisectors is determined separately. (This is of no concern if the layout is for an unattached pipe flange rather than for a valve flange.)


Be&work includes practically all repair work other than actual machining.

There are specific techniques that can be ased in assembly and disassembly of equipment which will improve the effectiveness of a repair job. You should note such things as fastening devices, fits between mating parts, and the uses of gaskets and packing when repairing equipment. Noting the positions of parts in relation to mating parts or tlie unit as a whole is extremely helpful in ensuring that the parts are in correct locations and positions when the unit is reassembled.

Inspecting the equipment before and during the repair procedure is necessary to determine causes of defects or damage. The renewal or replacement of a broken or worn part of a unit may give the equip- ment an operational status. Eliminating the cause of damage ptevents recurrence.

Repairs are made by replacement of parts, by ma- chining the parts to new dimensions, or by using hand tools to overhaul and recondition the equip- ment. Hand tools are used in repair procedure in jobs such as filing and scraping to true surfaces, and to remove burrs, nicks, and sharp edges.

Assembly and Disassembly

Equipment shouId be disassembled in a clean, well-lighted work area. With plenty of light, small parts are less likely to be misplaced or lost, and small but important details are more easily noted. Cleanliness of the work area as well as the proper cleaning of the parts as they are removed decreases the possibility of damage due to foreign matter when the parts are reassembled.

Before starting any disassembly job, select the tools and parts that you think will be necessary and take theh to the work area. This procedure will per- mit you to concentrate on the work without un- necessary interruptions during the disassembly and reassembly processes.

Have a container at hand for holding small parts to prevent loss. Use tags or other methods of marking to identify the parts with the unit from which they are taken. Doing this prevents mixing parts of one piece of equipment with parts belonging to another

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Figure 23. Mating parts location marks.

similar unit, especially if several pieces of equipment are being repaired in the same area. Use a scriber or prick punch to mark the relative positions of mating parts that are required to mark in a certain position (Fig. 23). You must pay close attention to details of the equipment you are taking apart to 5x in your mind how the parts fit together. When overhauling equipment, use no more force than necessary to dis- assemble and reassemble the parts. Double check for overlooked fastening devices if heavy pressure is re- quired to separate parts. An overlooked pin, key, or setscrew that locks parts in place can cause extensive damage if pressure is applied to the parts. If barn-- rners are required to disassemble parts, use a mallet or.hammer with a soft face (lead, plastic, or raw- hide) to prevent distortion of surfaces. If bolts or nuts or other parts are stuck together due to cor- rosion, use penetrating oil to free the parts.

Breclaion Work

In the repair of equipment, it is usually necessary to do a certain amount of precision hand finishing of parts. This requires the use of file, scrapers, precision portable grinders, and hydraulic and arbor presses. Machined parts are likely to have burns, wire edges, and small irregularities that must be removed by filing or offhand grinding. It is sometimes necessary to scrape in flat surfaces and bearings so that true surfaces and correct clearances are maintained. Hy- draulic and arbor presses are used to force-fit mating parts.

SCRAPING. Scraping requires the use of cutting tools, similar to files without serrated edges, to ac- complish precision work. A great deal of experience is necessary to become proficient in scraping a true surface. Scraping produces a more accurate surface than machining.

To scrape a flat surface, a surface plate and prus-

Figure 24. Checking a surface.

sian blue are required. Lightly coat the surface plate with blue and move the workpiece over this surface. The blue will stick to the high spots on the work- piece, thus revealing the areas to be scraped (Fig. 24). Scrape the areas of the workpiece surface that are blue and check again. Continue this process until the blue coloring shows on the entire surface of the workpiece. To reduce frictional drug between mating finished scraped surfaces, solid surfaces are usually r,;tated so that each series of scraper cuts is made at an angle of 90 degrees to the preceding series. This action gives the finished scraped surface a cross- hatched or basket weave appearance.

A shell-type split bearing, or a bushing, can be scraped, if necessary, to fit a shaft. To do this, a man- drel the same size as the shaft, or the shaft itself, is blued and placed in the bearing. Turning the man- drel or shaft slightly wiii mark the high spots which then can be scraped down. Scraping a bearing is more difficult than scraping a 5at surface, because longitudinal as well as radial clearance must be main- tained. Scraping is not often required in most repair- work, but when it is needed there is no other way to do the job.

REMOVAL OF BURRS AND SHARP EDGES. An impor- tant but often forgotten item in the repair of ma- chinery is the removal of burrs and sharp or marred edges from the parts before reassembly. Removal of burrs and sharp edges, i,n addition to being the mark of a craftsman; makes parts safer to handle, prevents interference in the fitting of mating parts, and pre- vents the possibility of having chips break off edges when the part is back in operation. Inspect parts of an assembly carefully, and when necessary, remove corners and burrs or marred edges with a file.

CLASSES OF FITS. The fit of a part is the dimensional relationship of one part with its rusting part. Types of fits may be placed in three general categories: the clearance fit, the transition fit, and the irnerference

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fit. The type of fit depends on the allowance pro- vided between the mating parts. For emmpk, a clearance fit requires that a clearance allowance be provided between the mating parts. The American Standards Association (ASA) has further classified these Sts according to use.

Cfearonce fits (running or sliding fits by ASA standards) have nine classi6cations varying accord- ing to the amount of clearance between the two mat- ing parts. These fits are used when one part moves in relation to its mating part. For e.mm&, a rotating shaft and bearing relationship, or the sliding action of a shaper ram.

Transitional fits (locational fits by AS.4 standards) are used for locating one part in relation to its mat- ing part. A transition fit may have a small clearance or a light interference allowance, depending on usage requirements. For exQm&, a small ckearance allowance would be used between the end bell and housing of a motor. This clearance permits relative ease of assembly and disassembly while retaining good alignment characteristics. A transitional inter- ference fit which would require only light pressure to fit the parts together might be used between an aligning dowel pm and its hole. This type of 6t pro- vides better alignment than the clearance allowance, but makes assembly and disassembly more difhcult.

Inter@rence fits (force fits by ASA standards) re- quire force to assemble mating parts. There are five classes of interference fits, varying from a light drive fit (class 1) to a shrink fit (class 5). Classes 1, 2, and 3 interference fits can usually be assembled by using mechanical pressure. In classes 4 and 5, heat or a shilling medium may be required to expand or con- tract one part so that the parts can be fitted together.

Using Hydraulic and Arbor Presserr

Hydraulic and arbor presses are simple but useful machines. They are used primarily in force-fitting parts when making repairs. Arbor presses, which con- sist of a gear and rack arrangement, are used for very light pressing jobs, such as pressing arbor into work- pieces for machining. Most hydraulic presses are manually operated.

Regardless of the type of press equipment used, be sure that it is operated correctly. The ordy method of determining the amount of pressure exerted by a hydraulic press is by watching the pressure gage. A part being pressed can reach the breaking point without any visible indication that too much pressure is being applied. When us:ng the press, you must


consider the interference allowance between mating parts, corrosion and marred edges, and overlooked fastening devices, such as pins, setscrews, and re- tainer rings.

To prevent damage to the work, observe the fol- lowing precautions when using the hydraulic press.

1. Ensure that the work is adequately supported. 2. Place the ram in contact with the work by

hand, so that the work is positioned accurately in alignment with the ram.

3. Use a piece of brass or other material (pref- erably slightly softer than the workpiece) between the face of the ram and the work to prevent mutila- tion of the surface of the workpiece.

4. You cannot determine the pressure exerted by feel. Watch the pressure gage; if excessive pressure is required, release the pressure and double check the work to find the cause.

5. When pressing parts together, use a lubricant between the mating parts to prevent seizing.

There are no set rules for determining how much pressure will be needed to force-fit two mating parts together. The distance that the parts must be pressed usually increases the required pressures, and in- creased interference allowances require greater pres- sures. As a guideline for force-fitting a cylindrical shaft, the maximum pressure, in tons, should not exceed seven to ten times the shaft’s diameter in inches.

Using an Oxyacetylene Torch

You may have to use an oxyacetylene torch to heat parts to expand them enough to permit assembly or disassembly. This should be done with great care. The operation of the oxyacetylene torch is not ex- plained in this book, but safety precautions which must be observed when using the torch and equip- ment are as follows.

1. Use only approved apparatus that has been examined and tested for safety.

2. When cylinders are in use, keep them far enough away from the actual heating area so they will not be reached by the flame or sparks from the object being heated.

3. Never interchange hoses, regulators, or other apparatus intended for oxygen with those intended for acetylene.

4. Keep valves closed on empty cylinders. 5. Do not stand in front of cylinder valves while

opening them. 6. When a special wrench is required to open a

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cylinder valve, leave the wrench in position on the valve stem while the cylinder is being used, so that the valve can be closed rapidly in an emergency.

7. Always open cylinder valves slowly. (Do not open the acetylene cylinder valve more than 1 l/2 turns. )

8. Close cylinder valves before movilig the cyl- inders.

9. Never attempt to force unmatching or crossed threads on valve outlets, hose couplings, or torch valve inlets. The threads on oxygen regulator outlets, hose couplings, and torch valve inlets are right- handed; for acetylene these threads are left-handed. The threads on acetylene cylinder valve outlets are right-handed, but they have a pitch which is different from the pitch of the threads on the oxygen cylinder valve outlets. If the threads do not match, the con- nections are mixed.

10. Always use the correct tip or nozzle and the correct pressure for the particular work involved. This information should be taken from tables or

worksheets supplied with the equipment. 11. Do not allow acetyiene and oxygen to awn-

mulate in confined spaces. Such a mixture is highly explosive.

12. Keep a clear space between the cylinder and the work. so that the cylinder valves may be reached quickly and easily if necessary.

13. When lighting the torch, open the acetylene valve first and ignite the gas while the oxygen valve is still closed. Do not allow unburned acetylene to escape and accumulate in small or closed compart- ments.

14. When extinguishing the torch, close the acet- ylene valve first and then close the oxygen valve.

These precautions are by no means all the safety precautions that pertain to oxyacetylene equipment, and they only supplement those specified by the manufacturer. Always read the manufacturer’s man- ual and adhere to all precautions and procedures for the specific equipment you are going to be using.

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Chapter 12

Drills, Drilling, and Drilling Machines

Drilling Procedures

There are many kinds of dri&, ranging from those for general purposes to specialized types for specific materials or operations. Various lengths and num- bers of flutes are available, with straight or various flute angles, with regular or special points, and with straight or tapered shanks. (See Chap. 3, section on drills. )

DriZUng has been described as “making holes in solid material with a tool called a drill.” This is a perfectly good definition, but it is somewhat like de- scribing a donut by the part you do not eat.

The worker would do better to think of drilling as “‘the forming of a workpiece by removing unwanted material with a drill.” This sounds like the same thing, but there is one important difference. It makes ns concorned with the surface as well as the position and dimensions of what is left, and after all, that is the whoie problem of driiiing.

There is a wide variety of drilling machines for drilling holes in metal, each of which has its par- ticular advantages for certain kinds of work. Among those in most common use are portable drills, sen- sitive drills, standard drill press, radial drills (trav- eling head drills), multiple spindle drills, gang drills, and other specially designed machines.

Before proceeding with actual drilling, the work should be securely fastened to the table of the drill press by one of the clamping and holding procedures described later in this chapter.

Checkiig the Drill Prior to drilling the hole, be sure that the drill is

the correct size, that it is sharp and firmly secured in the chuck of the machine, and that the work has been securely clamped or fastened. Proceed by carefully aligning the point of the drill with the mark previ- ously made when laying out the work and start the

machine. After the drill has run a few revolutions, it must be lifted to compare the cuts made with the circle previously laid out on the work. The cuts will sometimes be found to be off center. To correct, pro- ceed as follows: With a small roundnose chisel, cut a small shallow groove (Fig. 1) on the side toward which to draw the hole. Start the drill again and it will drift over to the correct position. Repeat the operation if necessary. Note that this must be done before the drill starts to cut its full diameter. Once the drill is cutting full size nothing can be done to remedy any inaccuracy.

DriUiuq Small Holea

Holes l/la in. in diameter and smaller should be drilled at a high speed. Use a special bushing to fit

Figure 1. Correcting off-center drill by grwving with chisel.


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Figure 2. Drilling large boles.

Figure 3. Drilling round stack, with piece cut from work for guide.

the spind!e of the drill press when drilling small- diameter, deep holes. This bushing should be suffi- ciently long so that the drill can be housed almost its full length inside the bushing at the start of the cut. When the drill has cut to the length of this extended portion, it should be set out another short distance and the operation repeated. If the full length of a small drill is extended at the start of the drilling operation, inaccurate holes and breakage of the drill may result.

Drflling Large Holes

A smaller-sized lead hole must be drilled before comple:ing the drilling of a large hole. Start to driII with the full-size drill, check, and draw the drill if necessary. After t’re driI1 has started to cut full size, change to the small drill and proceed to run it through the work to make the lead hole (Fig. 2). This smaller lead hole will now be exactly in the center of the layout circle. Then set the larger drill

into the spindle and drill the hole full size. The diam- eter of the small drilI used for the lead hole should be approximately the same as, or a little larger than, the web thickness of the larger drill. Since there is less tendency for a small drill to run off center than a large one, this procedure will result in a hole that is usually more accurate than if it were drilled by any other method (Fig. 2).

Drflffng Sheet Metal

Sheet metal must be backed against a wooden base block or, preferably, sandwiched between two blocks of wood and clamped. A bottom support must be used to prevent burring and crushing the metal.

Drfufng Round stock

A thin disc the same size as the work and prefer- ably cut from the end of the work should he used in setting up round stock for drilling (Fig. 3). This disc must be carefully laid out and center-drilled to the required diameter. Clamp both work and disc in a vise (Fig. 3). The disc will guide the drilI directly to the center of the work and will prevent drifting. Drifting often occurs when round stock is drilled by any other method.


Various types of countersink drills must be used to countersink the work for the heads of the various types of machine screws so that their heads come either flush with or below the surface of the material. This is done after the hole has been drilled to the depth required.

Drilling for Tapped Holes

The drill that is used preparatory to tapping or threading must be a definite size. See the table in the Appendix for accurate sizes of drills to use. The results produced by the use of various sizes of drills are shown in Fig. 4. At A, Fig. 4 the previously drilled hole was too small. The black area illustrates the amount of metal that should have been removed by the drill. The removal of this excess metal by the tap produced a rough thread. Tapping a drill hole that is too small may dull the tap and in some cases break it. If the drill is too large, the thread will be only partially cut, and this will necessarily weaken the holding power of the screw (B, Fig. 4). A hole

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Figure 4

must he drilled that will allow the tap to cut at least 7.5 per cent of a full thread (C, Fig. 4). To tap drilled holes on a drill press, a special tapping attach- ment must be used. This accessory is attached to the spindle and hoIds the tap in a solid chuck. Various columns are supplied with the attachment which take a range of tap sizes. The tap is advanced to the hole by means of a V-iever on the attachment. Speeds and feeds for tapping vary with the size of hole and material. Manufacturers of tapping attachments fur- nish speed-and-feed tables and specific directions for the use of their product. After tapping to the required depth, the tap automaticalIy reverses ro- tation and extracts itself from the work. The reverse rotation is usually about twice the forward speed.

Miicellaneous Drilling Machime Operations

Gn~xmx. When a suitable grinding machine is not available, light surface grinding can be done perfectly on the drill press by the use of a cup wheel

Fimre 5

mounted on a special spindle. The grit and bond of the wheel should be selected to suit the work. Vari- ous types of wheels are fuliy described in Chapter 18. The speed of the drill press should be about 5,000 rpm. The work is projected along the drill press table and under the cup wheel. This wheel must be set to take a suitable bite, and the quill must be locked in position. Heavy cuts should be avoided. A column collar can be used under the drill press head. Clamp the work in place in the vise (Fig. 5), and swing the drill press bead back and forth across the work.

POLISHING. The spot finish, sometimes called the engine finish, is an attractive finish for metal and can be done on the drill press. All that is required is a rod of hard rubber or a hardwood dowel. The drill press should run about 1,200 rpm. A paste can be made which consists of abrasive grains such as emery, aluminum oxide, or silicon carbide, of about 150. Grit mixed with oil, or a commercial valve grind- ing compound mixed with either oil or water, can also be used. Spread the paste lightly and evenly over the suface of the metal and then feed the revolving rod onto the work. The rod tip grinds the abrasive grains into the metal, producing a circular spot.

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Repent the operation, overlapping the rings a little, until the whole surface is covered. The line of spots should be regularly spaced and kept even by means of a fence. A uniform feed pressure and duration of contact must be practiced to get good results. Many &ectivc patterns can be worked out (Figs. 6 and 7).

Figures 6 and 7.

Figure 9

Figure 8 Figure 10

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DRILLING IN GLASS. Glass is drilled with the use of a steel or brass tube of the diameter desired for the hole. The tube is slotted at the working end with a saw cut. blark the glass with a grease pencil and build a dam of putty around the spot where the hole is to be drilled (Fig. 8). The tube drill is fed with a mixture of SO-grit silicon carbide abrasive grains combined with turpentine. The drill speed should be about 500 rpm. Speciaily designed spear-point car- bide-tipped tools are also available for drilling in glass.

BUFFING. When special buffing equipment is not available, polishing and buffing with cloth wheels can be done on the drill press. An inexpensive arbor he!d in the chuck as shown in Fig. 9 will hold a canvas bu5ng wheel. With buffing compound applied (Fig. lo), a good job of polishing can be obtained o11 a variety of materials.

The Radial Drilling Machine

The radial drilling machine shown in Figs. 11 and 12 was so named because the arm which carries the head of the machine swings on a column, and is always radial to the column. This machine is ex- tremely useful when it is necessary to drill several holes in large and heavy pieces. The radial drill, because of its wide range and versatility of operation,


has taken the place of the larger upright drills to a certain extent in large production shops. The spindle head of this drill is mounted on a radial arc which is fastened to the column. The head of the radial driI1 is adjustable along the arm, and the arm of the ma- chine can be swung to any desired position. This adjustment is used when drilling holes in large pieces

Figure 12. Rear view of standard radial drill.

Figure 11. Parts of a radial drill.

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which cannot be placed on the table of the machine; it permits the operator to locate the cutting tools q:lickly over any point of the work within a con- siderable area. The arm of this drill can be raised or lowered to accommodate quite a range of height in pieces of work. ,~is a rule, radial drills are classified as to size by the length of the radial arc.

Radial Lriuiing Ma&ine Operation

Before starting tl;e machine, pot the driving cluich lever, shown in Fig. 11, in neutral (midway between its extreme positions). Push the quick-return levers toward the head as far as they will go; then turn the machine over by hand so that it revolves freely. By means of temporary ~onncztions, check the direc- tie?? of rotation of the driving motor. When the motor rues in the direction indicated on the machine, these connections can then be made permanent. To run the spindle of the machine right-handed, as in drilling, pull the driving clutch lever forward as far as It will go. To run the spindle left-handed, as in backing out taps, push the driving clutch lever to- ward the arm as far as it will go. To stop the spindle, put the driving cl&& !ever midway between these two positions.

.4void running tbe spindle of this machine when the driving clutch lever is not in either of the extreme positions. A partially. engaged clutch will slip, caus- ing wear on the machine. The super-service type of radial shown in F’ig. 11 has 36 spindle feeds. The speed-change lever, A, Fig. 11, provides nine changes of speed. The back-gear levers E and C, Fig. 11, each provide two changes of speeds. The nine speeds ob- tained through lever A, when multiplied by the four speeds obtained through back-gear levers B and C give a total of 36 spindle speeds. The nine positions of speed-change lever A are indicated by an arrow and a numbered plate at the upper end of the lever. These numbers correspond with numbers on the cen- ter column of the speed plate (Fig. 13a), usually affixed to the machine by the manufacturer. The back gears B and C have two positions each; one is the horizontal, the other a downward position. The positions of these levers are indicated by arrows at the top of the speed plate.

All of the 36 changes of spindle speeds are ob- tained on this machine through sliding gears. To shift these gears, it is only necessary to engage the driving clutch of the machine very lightly, just enough to cause the gears to roll slowly, and then to shift with a quick decisive movement. The speed plate is

calibrated for direct reading, and gives the spindle speed in rpm and the corresponding sizes of drills necessary for boring and facing cutters for cast iron and for steel. Drill diameters for cast iron are based on a cutting speed of 100 feet per minute, and are given on the affixed speed plate. The size of the boring and the facing cutters for cast iron is based on a cutting speed of 50 feet per minute, and indicated on the machine.

Drill diameters for steel are based on a cutting speed of 80 feet per minute. The size of the boring and the facing cutters for steel is based on a cutting speed of 40 feet per minute, and is also indicated on the machine. The speeds recommended for both cast iron and steel are also given on the affixed speed plate.

Figure 13a

Figure 13b

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a half-inch of its lower limit of travel. This prevents the teeth of the rack pinion from running into the spindle sleeve at the end of the rack.

SELEmON OF FEEW The super-service radial (Fig. 11) has 18 feeds. The feed lever D, Fig. 11, provides nine changes of feed. These are doubled by the feed le-m E, F’- ‘6. 11, OXL. Gng a total of 18 feeds. The nine positions of lever D are k3icated by an arrow and a bronze plate at the uprjer ead of the lever, the num- bers corresponding with the top row of numbers of the feed plate affixed to the m::chine. Lever E has two positions, between which Is a neutral position at which it may be set for %xl speeds.

To start the spindle feeding downward, run the )I spindle in tbe direction for drilling and set the feed

levers D and E according to the position indicated on the feed plate. Pull the quick-return lever shown in Fig. 11 away from the head as far as it will go. This engages the quick-return clutch. To stop the feed at any time, push the quick-return lever toward the head of the machine.

A safety c!lutch is also provided on this machine which will slip if the feed is overloaded, preventing damage to the mechanism even though the mechanic might become careless in selecting or tripp;ng the feed.

All of the 18 speed changes are obtained on this machine by means of gliding gears. Speeds can be changed while the spindle is running idle without

;, disengaging the driving clutch, but they should not ::, be changed while drills or tools are actually cutting. : The feed plate (Fig. 13b) furnished by the manu-

facturer usually gives feeds in thousandths of an inch per revolution of the spindle. For driving pipe taps, select the feed corresponding to the lead of the tap.

,‘, The spindle will then automatically advance the tap at its required rate. On the type of machine shown in Fig. 11 there is a limit trip that disengages the power feed of the machine when the spindle comes within

The teed mechanism of a modern radial drill inn- eludes a dial and depth gaugi: u: the compensating type. The depth gauge automatically disengages the feed when either the point or de body of the drill has penetrated to the required depth. The gradua- tions on the ring represent spindle travel in sixteenths of an inch. The graduat:on on the etched plate rep- resents drill diameters in eighths of an inch. To ad- vance the drill to a given depth, set the point of the drill so that it touches the work. Unclamp the gradu- ated ring by swinging the depth-gauge clamping iever in a’ clockwise direction until it points down- ward.

To advance the point of the drill to a given depth, ievolve the graduated ring until the point on the ring that corresponds to the required depth registers with the zero on the etched plate; this shows the depth gauge set to trip the feed when the drill point has penetrated to a depth of 2% in.

To advance the body of the drill to a given depth, revolve the graduated ring until the point on the ring corresponds to the required depth and registers with the drill diameter indicated (Fig. 14). Figure 15 shows the depth gauge set to trip the feed when the body of a two-in. drill has penetrated to a depth of five in. When these settings have been made, swing the depth-gauge clamping lever upward until the graduated ring is firmly clamped and engage the feed; when the drill reaches the required depth, the feed will automatically disengage.

Figure 14

MOVING THE HEAP ON THE ARM. The head of the machine can be moved along the arm with the head- moving hand wheel (Fig. 11) or by the power rapid- traverse lever (Fig. 11). To move the head by the power rapid-traverse lever, pull the traversing lever down to its lowest position and move it to the right or left according to the direction in which the head is to be moved. When the head is in the position required, release the lever, and it will return to neu- tral. The hand wheel can be used for final close positioning rs the head of the machine. In addition to moving thr: head swiftly and easily along the arm, the power rapid-traverse can be used in the same manner as the traversing motor on an electric crane.

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Heavy tools can be placed on a bench cr tool stand near the column and carried to and from the work by means of the power traverses This relieves the mechanic of heavy lifting in getting tools on and off the heavy spindle. To clamp the head on the arm, pull up hard on the head-clamping lever (Fig. 3.1); to unclamp, push it down.

R.usnw, Lowuuiw, *xn C~IPING THE ARM. Arm clamping and elevating are conveniently and safely controlled at the operating position by a free-moving directional lever, Al Fig. 16, at the lower left side of the head. On moving this lever upi the arm clamp is hydraulically released, the multiple-disc clutch for elevating is automatically engaged, and the arm rises. To stop elevation, the lever is moved to the “stop” or center position. This automatically disen- gages the elevating clutch, and the arm is automati- cally clamped through a powerful hydraulic clamping mechanism. The cycle for lowering and clamping is similarly automatic and foolproof. F.otective limit trips are provided at the upper and lower limits of travel, and, in addition, there is a safety in the mount- iog of the elevating screw to prevent damage should the arm be lowered onto any obstruction within its limits of travel.

Hydraulic column clamping on the standard ma- chine is controlled from the head as shown at B, Fig. 16. Its push-button control at the head marked “clamp” and “release” operate a solenoid controlling the hydra&t, mechanism that is built-in at the motor

end of the arm. The hydraulic clamp, through two bolts on the cuff of the column sleeve, automatically ! applies up to 55,000 pounds of pressure on the col- 1 umn and sleeve clamping surfaces, joining these two i members as effectively as if they were one solid part.

ADJUSTING ARM CLAMP. To adjust arm clamp, stop the main driving motor of the machine and remove link J on the xlutch-shifting mechanism in the rear of the arm. Also remove the plate H on the front of the arm-clamping mechanism.

The upper and lower limit screws must not be moved or adjusted. They are merely for the purpose of controlling the amount of expansion of the arm when the arm is unclamped and are properly set at the Iactory.

Now start the main driving motor of the machine, set the arm-control lever mounted on the head of the machine in either up or down position. This will unc!amp the arm and, since link 1 has been dis- connected from the elevating clutches, the arm will not raise or lower. When clamping or unckmping the arm, the push rod and equalizing bar Ioc.lted in the bracket under plate N should travel a total distance of between l/2 and %%a of an inch. Measure this travel by causing the rod to move out when the elevating-control lever is moved to the neutral posi- tion. This measurement can be taken from the ma- chine surface on the end of the bracket where plrtte If is fitted. If the clamping rod is not traveling be- tween % and yla inch, then either. one or both of

Figure 16

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the arm-clamping levers are adjusted too tightly. When this happens, the nuts G must be loosened to permit full travel of the clamping rod.

To adjust the clamp, unclamp the arm and adjust the upper and lower adjusting nuts so that the equal- izing bar on the end of the push rod is held in a vertical position when the arm is clamped. Make this adjustment between the upper and lower levers slowly, being sure that the equalizing bar remains in a vertical position to insure proper clamping at the upper and lower portions of the arm.

When adjusting the nuts slowly, clamp the arm after ea& adjustment. If the nuts have been tight- ened to a point where the push rod fails to travel its full amount, the r/a to %s of an inch previously checked, then back off each nut one-half a turn. Check to be sure that the push rod is making its full travel and that the equalizing bar is in a ver- tical position when the arm is clamped. The arm is now properly adjusted. Stop the driving motor aud, with the arm in a clam,-ed position, replace plate H and the elevating-clutch connecting link.

ADJ~TSTING THE COLUMN CLAMP. The column clamp is located at the rear of the machine and at the bottom of the column sleeve (Fig. 17). To set this clamp, have the main driving motor of the machine running, and then push the column electric-control button, mounted on the head of the machine, to the unclamped position. This will rotate the vertical clamping shaft approximately 90 degrees. On the lower end of this shaft is mollnted an eccentric which rotates against the roller. In the unclamped posi- tion of the column, the high point of the eccentric is rotated away from the roller. When the column is adjusted at the factory, the nuts are properly adjusted to control the amount the sleeve cuff will open when the column is in the unclamped position.

To adjust the column clamp, he sure that it is unclamped and that the eccentric is away from the roller. Hate a wrench on the end of clamp bolts B, and adjust the nuts until an approximate s/16-inch (as indicated on the column-clamp adjusting plate) clearance between the roller and the eccentric is obtained. Care should be taken when adjusting the nuts to see that both the upper and lower nuts have approximately the same tension when clamping. Clamp the mechanism by pushing the column-clamp button on the head of the machine, and then check to see that the high point of the eccentric is against the roller and that the shaft has rotated its full dis- tance. Care should be taken at this point to be sure that the eccentric or shaft has rotated its full dis- tance, otherwise the arm clamp on the machine


Figure 17

will not function properly. After the machinist is certain that the eccentric shaft has traveled its full distance, the column clamp thus adjusted should be satisfactory. If the column is not rigidly clamped for any reason, additional adjustments should be mad. on nuts A as previously described. Be sure that the high point of the eccentric will still rotate to its limit against the roller. The machine is now ready for operation.

Drilling Machiiea

Drilling machines or drill presses of various types are used in the machine shop for drilling holes in metal. Those generally used are the portable drills previously described in Chapter 3, sensitive drills, standard drill presses, floor and bench types of column drills, radial drills (traveling head drills), multip!e spindle drills, gang drills and other speciaily designed machines.

SensItive Drills

For very light work where it is necessary to feel the action of the drill point as it penetrates the work, the modern sensitive drill shown in Fig. 18 is used. It is used for center driiling in machine shops where a special machine for this purpose is not practicable. No gears are used to drive the spindle. The drive is entirely by beIts. Nothing hut a hand lever, pinion, and rack on the spindle intervenes between the hand of the operator and the drill point. The spindle is bored out to a No. 1 Morse taper. Drills with shanks of this taper can be used direct, or a drill chuck (with a shank) to fit this taper can be used.

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Figure 18. Sensitive bench drill press.

Standard Drill Press

The standard drill press (Fig. 19) is used for heavier work. It has back gearing similar to a lathe together

with a power feed. The principal differences be- tween the standard drill press and the sensitive drill are its greater weight and rigidity, the strength and size -’ ‘ts moving parts, the range of its spindle speed-, Its power feed, and its greater power due to the use of cones and back gears.

Radial DrilIa

In the case of the radial driII, the drill spindle is carried in a traveling head on a horizontal arm. The

head that carries the spindle can he located at any point in the range of the machine along the arm. In

addition, the horizontal arm can be swung in a hori- zontal plane, raised or lowered, and clamped rigidly in position. These machines of the type shown in Figure 20 are used for jobs where the work is so heavy

Figure 19. Parts of a drill press: (1) Main driving gears, bevel, (2) Back gears, (3) Upper ccme pulley, (4) Frame, (5) Feed gears, (6) Counterweight chains, (7) Feed gear driving shaft, (8) Spindle, (9) Back gear lever, (i0) Column, ( 11) Automatic spindle feed stop, (12) Spindle sleeve, (13) Feed trip lever, (14) Hand feed wheel, (15) Spindle quick return lever, ( 16) Feed gearing, ( 17 ) Feed box, ( 18 ) Feed change handle, (19) Sliding head, (20) Sliding head ways, (21) Back brace, (22) Belt shifter, (23) Rack for elevating table, (24) Table arm clamping screws, (25) Pulley stand, (26) Lower cone pulley, (27) Belt shifting fingers, (28) Tight and loose pulleys, (29) Table, (30) Table clamping screw, (31) Table arm, (32) Table elevating gear, (33) Base, (34) Ball thrust spindle bearing.

that it is more practicable to bring the drill into position by means of the horizontal arm than to move the work.

Universal Radiul Drills

Although similar in design to radial drills, these machines have a traveling head that can be swung to any angle in a vertical plane. The horizontal arm can be swung in a horizontal plane, and, in addi- tion, it can be swiveled on its axis, thus enabling the machine to drill holes at any angle (Fig. 20).

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,,,, :; ,’ ,: ,: il :g::,,

Figure 20. Parts of n Universal &dial Drill: (1) Vertical driving shaft gear, (2) Center driving shaft gear, (3) Elevating tumble plate segment,

‘,:, :

(4) Elevating screw gear, (5) Column cap, (6) Vertical driving shaft, (7) Column sleeve, (8) Elevaticg lever shaft, ( 9) Elevating screw, ( 10) Arm girdle, (11) Am clamping lever, ( 12) Spindle driving miter gear guard, (13) Arm rotating worm, ( 14) Arm indicating pointer, ( 15) Full universal arm, (16) Arm clamping nuts, ( 17) Arm locating pin, (18) Arm driving shaft, (~ 19) Arm ways, (20) Spindle head traversing rack, (21) Saddle, (22) Spindle reversing lever, (23) Back gear lever, (24) Spindle head swiveling worm, (25) Spindle feed trip lever, (26) Depth gage dial, ( 27) ‘Jniversal spindle head, (28) Spindle quick return lever, (29) Spindle feed rack worm shaft, (30) Spindle, (31) Spindle feed rack, (32) Spindle sleeve, (33) Saddle clamping lever, (34) Spindle feed handwheel, (35) Spindle head traversing gear, (38) Arm swinging handle, (37) Arm elevating lever, (38) Clamping ring, (39) Clamping ring handle, (40) Column, (41 j Main driving miter gears, (42) Driving shaft coupling, (43) Driving pulley, (44) Speed change lever, (45) Speed change case, (46) Box table, (47 ) Base.

Multiple Spindle Drill

The drill shown in Fig. 21 is used on production work requiring holes of a variety of sizes. Two or more spindles are driven from the same driving shaft by worms and worm gears or belts. The table is not usually adjustable except on certain types. The spindles can be moved along the cross rail (on some machines) and set the required distances apart v&hin the range of the machine. This type of drill is used for plate work, structural iron, or light work requiring a number of holes in a straight line.

Universal Multiple Spindle Drill

This type of drill (Fig. 22) has a cluster of drill spindles held in a head that can be raised or lowered and clamped in position on the column. The spindles

are driven by means of universal joints and can be set at variable distances apart. Jigs should he used when work is to he done with spindles driven by universal joints.

Gang Drilla

The gang drill shown in Fig. 23 is an assembly of from two to eight single drill presses. They are mounted on a single base with an adjustable work tabIe as shown in Fig. 23. Although combined in a single unit, the vertical adjustment of each of the heads and also the speed and feed units of each spindle can be adjusted individually and independ- ent of one another. This type is a production machine and is used for work held in a jig that can be readily shifted from spindle to spindle as required.

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a coil slxiug. Adjustments are provided for locking t11c quill and presetting the depth to which the quill can travel.

SEE. The name size of the drill press is expressed in terms of thf di;u~xter of the largest circular piece of work which cxn he drilled through the center while 011 the drill press table. Thus. a 14-inch circle can hr ccntrr drilled on :a 14-inch drill press; or, in other wrl-~1s. the distance from the center of the spidc to tlw Il-mt of the colunm is 7 inches. An- o!l~~,r- imlr\ to sixI, is tlrc* distance Iwtwcen the end nf tlw spindle x11(1 the tal)lr, this hcin~ much greater iI3 ‘low mr~lrls tlxw in hcuch models. In both cases, the depth of the lwlc~ which c’~~~~ lx drilled with one stroke of thr feed lcwr is about 1 inches.

PO\VIX \xn SI+:ED. The drill press is usually fitted xvi& corn:: pulleys so that sclcctivc spwds can be ohtaiwxl. 7‘11c avcr~gc rang<’ of speeds is 590, 1,275, 2.-W m1d 5,000 wwhtions per minute. ‘As a general 1.111( , ii Llqcr cow pullry is ~~scd in the machine shop 011 t!rc spill& tc give speeds of about 390, 745,

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Figure 22. Universal multiple spindle drill.

1,280 and 2,050 rpm. Because the shaft stands ver- tically, only a sealed ball-bearing motor should be used as a power unit. For average work, a one-third horse power motor is used for ali requirements, this being the approximate power required to push a 1/$inch drill through high-speed steel.

BELT TIGWIOX. The belt tension is adjusted by mov- ing the motor closer or farther from the spindle (Fig. SX), locking tbe motor bracket at the required position, There. should be enough slack in the belt so that it will “blow out” on the slack side (Fig. 25 ) A belt that is too tight will cause excessive heat- ing and vibration. On the other hand, the belt must bc su%ciently tight so that it will not whip against the column when the drill press is in operation.

Figure 23. Gang drill.

Figure 24.

INSERTING DRILLS. Figure 35 shows the method for chucking drills in a keyless chuck. The drill is held in the third and fourth fingers of the left hand, and the chuck is gripped by the thumb and first and

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second fingers. A pull on the belt with the right hand secures the drill in the chuck. Drills are removed in the same manner, except that the belt is pushed away from the machinist. The insertion of drills and other tools in a spindle which has a hole in the end to receive the shank of the drill is quite simple; the drill is pressed into the hole and the set screws tight- ened to hold it. Where taper-shank drills are used, the drill is fitted by pressing it into the tapered hole at the ends of the spindle and engaging the tang of the drill in the corresponding slot in the qpindle. During the course of the work, the drill becomes (tightly wedged in the tapered hole and must be driven out by means of a drift key (Fig. 27). One edge of the drift key is flat and the other round. The round edge fits against the upper round part of the slot in the spindle, and the flat edge fits against the end of the drill being removed.

CxNxxRING TABLE. In average drilling operations, the hole in the center of the table should he directly under the drill, so that the drill, after going through thr work, will enter the hole in the table. Where

buEv Figure 25

Figure 26. Inserting a drill in a keyless chuck.

Figure 27

Figure28. Scribed line centers the table.

through drilling is being done, the feed handle should always be pressed without the work in place to see that the drill enters the table opening. Another rncz:i:o: of checking the proper table position is to scribe a line on the column. This should be done with the table properly centered by means of a suitable round rod (Fig. 28 ). A mark is punched on the table collar in line with the scribed line, and a similar mark is punched on the underside of the head.

ADI~STING SPINDLE RETURN S~nmc. For the pur- post of automatically returning the spindle upward after a hole has been drilled, a coil spring enclosed in a metal case is fitted to the side of the drill press. This spring is adjusted at the factory and usually requires no subsequent adjustment. If, however, the spindle fails to return to a normal position, or if the return is too violent, the tension should be adjusted

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accordingly (Fig. 23 ) . This is done by loos;~ring the locknuts which hold the case in place. They should not be completely removed, but hacked off abont z/4 inch so that the case can be pulled out to clear the bosses on the head. As the case is pulled out, it must be held tightiy to prevent the spring from unwinding. The case is turned clockwise to loosen the spring; counterclockwise to tighten it. ‘When the qui!l is up, two full turns from a nontension posi- tion should give the proper tension. Before adjust- ing,the spring, it is well to slack it off entirely. When thie is done, the spindle should be perfectly free. It may he jammed, however, by one or ‘both of t*vo things; first, the bolt beneath the qlrill lock may be drawn too tight, thus locking the quill; secondly, the screw fastening of the pulley may be turned in so tightly as to bind the spindle. If the spindle

~, does not mo~vz freely when released from the ten- sion of the spr ‘-7 a check should. be made at these

,;:,: two points bar: ‘IL %msioning. Excessive turr.ing ,:,j should he avoide? vhen resetting the locknuts hold- ? ‘, ing the spring case because this will also lock the i:~‘, quill. ~,,,~~, TILTING TABLE. The table can be tilted by loosen- ‘::, ing the nut under the table. A pin, fitting through ,,, !!,I corresponding holes, provides a positive stop at both ,;j! “, the level and the vertical positions. A hole can be ,:, : drilled to locate the 45-degree position, or a punch

can be made (Fig. 30) to locate this table position. Whether this is worthwhile or not wilI depend upon the nature of the work to be done. Where average work requires the setting of the table to various angles, to fit a scale and adjustable pointer to the underside of the table to locate these positions.

Toor.s AND ACCFSSOFUES USED. The tools used for drilling, reaming, boring, counterboring, countersink- ing, spot facing, and tapping are shown in Fig. 31. All of these operations, with the exception of tap- ping, can be accomplished with either a straight- shank or a tapered-shank tool. A1I sizes of drills and reamers under l/a in. are usually provided with

Figure 30. Table tilt5 right and left with positive .,‘~,,c~r at level and ve-tical posit”Jns.


Figure 31 Figure 29. Adjusting spindle return spring.

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Figure 32. Parts of a twist drill.

straight shanks which can be conveniently and firmly heId in the chuck of the drill press. Taper-shank tools for these small sizes are not necessary. Hold the larger siz6s in the drill press by means of the taper shank.

Drilling is the operation of producing a circular hole by the removal of solid material for which the twist drill is used (Fig. 32).

Reaming consists of both sizing and finishing a drilled hole. A reamer is a tool with several cutting edges ( Fig. 31)

Enlarging a drilled hole by means of an adjustable tool is called boring. A boring tool which has only one cutting edge is-used (Fig-31 ).

Cylindrically enlarging only the end of a drilled hole to a predetermined distance is called counter- boring (Fig. 31) .

A spot-facing tool is used for smoothing and squaring the surface around the ends of a previously drilled hole to seat a nut or the head of a capscrew (Fig. 31).

SLf$E’, ’



Figwe33. Dtiff press socket and sleeve.

The forming of internal screw threads in a previ- ously dri!led hole is called tapping, and the tool used is called a tap (Fig. 31). To use the tap, a reversible motor or a reversing accessory called a tapping at- tachment is necessary.

Tools with taper shanks too small to fit the taper hole in the drill-press spindle are held in a special socket. The shank of this special socket fits into the standard spindle hole. The attachment is called a drill-press socket and sleeoe (Fig. 33 ). Note that the taper-shank socket and sleeve has a flattened end forming a tang. This tang fits into a slot at the end of the taper hole and helps drive the drill (the hold of the taper alone is not sufficient).

HOLDING~THE WORK. With the exception of very heavy pieces, all work must be firmly secured to the table of the drill press to assure accuracy. If a yise is used to hold the work, it must be clamped to the table. The four types of clamps generally used are, the strap, bent, finger, and U-clamps (Fig. 34 ). A single clamp can safely be used to secure small work. For larger work, two or more clamps must be used (Fig. 34 ). The tables o! ~1.11 drill presses ?.re pro- vided with T-slots. Thes’ Gv.~ are used for the loca- tion of the necessary bolts to secure the clamp or other holding fixture used. Several types of bolts are used for various kinds of work. The square-head bolt is used for ordinary clamping purposes; how- ever, it has to be pushed along the T-slot from one end (Fig. 35 ) for placement. The T-head bolt is more convenient to use. It is set in place by dropping the head lengthwise in the slot and turning it to the right. This type of bolt .is especially convenient



Figure 34. Types of ckmp.

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when it is necessary to clamp the inside of work that otherwise would have to be lifted over the bolt (Fig. 35). The tapped T-head bolt is sometimes pre- ferred because the stud of this bolt can be removed and the head pushed along the slot under the work to the required position. Machinists usually have studs of various lengths with a few heads to be used when necessary. This practice obviates the need for a supply of different types of bolts of varying



Figure 35. Clamping-b& designs

Figure 36. Strap and step block for clamping work.


Figure37. Clamping various shapes of work.

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Step blocks are used in conjunction with bolts and clamps to secure the work to the drill-press table. These are available in various sizes and with various numbers of steps (Fig. 36). Note that the block used under the outer end of the clamp can be made of either scrap metal or hardwood. If wood is used, be sure that it is of sufficient cross section to give it the needed stiffness. Set it under the clamp with the pressure against tbe grain of the wood. The setups shown in these illustrations are merely suggestions; they can be altered to suit varying conditions, but the work most at all times be firmly secured. If the work is fastened directly to the table of the drill press, it must be located so that the drill or tool used will pass through one of the table openings. If the work cannot be centered over one of the openings, it must be mounted on either wood blocks or pieces of machined bar stock called parallels (Fig. 37 ).

When a light piece of metal is supported at points too far apart, it will spring under the pressure of the drill, resulting in an inaccurate hole and often a broken drill. To prevent the work from springing, use a V-support or block made of hardwood (Fig. 37 j. A V-block is used in conjunction with a step block, clamp, and bolt to secure round wotk for drilling; angle plates are used to secore odd-shaped work (Fig. 37 ). Other methods of securing work are shown in Figs. 38 and 39.

L~vowr OF WORK. Lay out the work prior to drill- ing as follows: By means of intersecting lines, show

the position of the center of the hole that is to be drilled. With a center punch make a slight mark at the point of these intersections. If the work is rough, rub chalk on it. If the surface of the work has been machined or is smooth, use a coating of blue vitriol solution instead of chalk. Let it dry for a few minutes before scribing the surface. Using the punch mark as a center, scribe a circle indicating the size of the hole to be drilled with a pair of dividers. Before pro- ceeding to drill the hole, use a larger center punch to make a larger indentation at the center.

SPEEOS AND FEEDS. Speed as applied to a drill is the speed at the circumference of the drill. This speed is called the peripheral speed and is the speed at which the drill would travel if it were laid on its side and rolled. In other words, a drill with a stated peripheral speed of 30 feet per minute would roll 30 feet per minute. As general!y used, therefore, speed of a drill does not refer to rotation per minute unless it is specifically stated. As a rule, a drill does not pull itself into the work, but requires a constant pressure of feed to advance it. This advance is always measured in fractions of an inch per revolution and is called feed. Feed pressure is the pressure required in order to maintain the necessary feed.

The correct speed and feed are dependent upon so many conditions that it is impossible to give hard- and-fast rules regarding them. The suggestions given should be considered only as a guide and as a point from which to start operations.

SI‘~~TING SPEEDS. To start a drill, bring it down

Figure 38. Using two types of strap clamp.

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Figure 39. Support with cut-out eliminates spring in drilling thin material.

to the work by hand feed until it centers itself in the work; then and only then, apply the power feed. Compositio,] and hardness of material, the depth of hole required, the lubricant used, the type of machine used, the condition of the machine, the setup, the quality ai the point grinding, the quality of the holes desired, and many other items have a distinct influ- ence on the speeds and feeds required. The correct speeds and feeds should be determined by good judg- ment and triai in each instance.


Aluminum and its alloys 20%300 Brass aad bronze, ordinary . ZOO-300 Cast iron, soft . . 100-150 Cast iron, hard 70-100 Malleable iron . 80-90 Magnesium and its alloys . 250-400 Moue1 metal . 4050 Steel, annealed . . . . . . . . . . . . . . .._..__...... m-70 Steel forgings . SO-60 Steel alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . So-70

If carbon steel drills instead of high-speed drills are used, they should be run at half the speeds given in the table.

When the extreme outer corners of the cutting edges wear away too rapidly, it is evidence of too much speed. High speed in cast iron tends to wear away the margin of the drill. The maximum speed suggested for carbon drills in cast iron is 50 feet per minute peripheral speed.

STARTIXC FEEDS. The starting feed is largely gov- erned by the size of the drill used and the material to be drilled. The general rule is to use a feed of .OOl in. to ,002 in. per revolution for drills smaller than ?& in.; ,002 in. to ,004 in. for drills r/s in. to *A in.; ,004 in. to ,007 in. for drills i/4 in. to r/a in.; 907 in. to ,015 in. for drills r/a in, to 1 in.; and ,015 in, to .025 in. for drills larger than 1 inch. Start the drill

with a moderate speed and a moderate feed. In- crease either one or both after careful observation of the condition of the drill. The foI!owing sugges- tions should be carefully observed. If the drill chips out at the cutting edge, it indicates either too heavy a feed or too much lip clearance. Before deciding that it is too heavy a feed, check the lip clearance of the drill. A drill that splits up the web may have been given too much feed for the amount of lip clearance. Either decrease the feed or increase the lip clearance, or both.

Faihue to give su5cient lip clearance at the center of a drill will also cause it to split up the web. On the other hand, too much lip clearance at the center (or at any other point on the lip) wiU cause the lip to chip. Make certain that the drill has been prop- erly ground. If it has been properly ground, then decrease the feed.

It is better to err on the side of too much speed than on the side of too much feed. This is true for all metals with the exception of cast iron. The nature of this material permits an unusually heavy feed. Speed can be increased to the point where the out- side corners of the drill commence to show signs of wearing away. The speed should then be slightly reduced.

Luaarcn~~o~ FOR DRILIJNG. Lubricants called cool- ants are used to cool both the edges of the tool and the work that is being machined. As large a volume as possible of the coolant should he directed onto the cutting edges of the tool and allowed to flow

onto and around the work (Fig. 40 ). Proper lubrica- tion aids in chip clearance and improves the finish of the hole.

Suggested lubricants for various metals are: Aluminum and its alloys--Soluble oil, kerosene, and

lard-oil compound; kerosene and soluble oil mixtxxres. Brass-Soluble oil, kerosene, and lard compound; light

nonviscous neutral oil. Copper-soluble oil. Cast iron-No lubricant required. Malleable iron-Soluble oil. Monel metal-Soluble oil; mineral oil. Steel (ordinary)-Soluble oil; mineral oil. Steel (very hard)-Soluble oil; turpentine.

Figure 40. Lubrication points on drill-press head.

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Milling Machines

The milling machine produces one or more ma- chined surfaces on a piece of material-the work piece-by means of one or more rotary milling cutters. The work piece is usually held securely on the work table of the machine or in a Gxture or jig that is clamped to the table. It is fed to the cutter or cutters by the motions of the table, or the work and cutters may both be moved in a definite relation to each other.

The existing types of milling machines are very numerous and their designs merge into one another to a great extent. However, the most common are the knee-and-column (including vertical spindle) (Fig. l), manufacturing, automatic, duplex. planer and drum types, together with special and single- purpose machines. We shall only describe the knee- and-column and manufacturing types because they are the most common. In general, the same princi- ples apply to all types. Figure 2 illustrates the parts of a typical milling machine.

Knee-andColuma Miig Machines

The knee-and-column milling machine has a rigid column, in which is mounted the spindle, and a table supported by a vertically adjustable knee (Fig. 2). Provision is made for horizontal movement of the table both parallel and at right angles to the axis of the spindle. The combination of vertical, transverse, and longitudinal table movements is found only in the knee-and-column machine, thus giving this type advantages on general milling work. Plain, universal, vertical spindle, and some auto- matic machines are of this design.

Manufacturing Miiq Machines

The manufacturing milling machine is character- ized by fixed table height (Fig. 3). Vertical adjust-


ment is obtained by an adjustable spindle bead, and only slight transverse movement is provided. These machines are noteworthy for their rugged construc- tion and the ease with which they are operated. “Lincoln” type, duplex, and some automatic milling machinas come under this classification.

The milling machine shown in Fig. 3 has a com- plete electrical control for all table feed, speed and spindle movements which aids in exceptional rapidity and precision, The unusual range of feeds and speeds

Figure 1. Vertical knee-and-column type milling machine.

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Figure 2. Operating Controls and Principal Parts-Uni- ,, versa1 Milling Machines: ( I) Machine start-stop lever, (2)

Inner arbor yoke, (3) Overarms, (4) Outer arbor yoke, (5) tini\-ersal Spiral Index Centers Footstock, (6) Adjustable arm braces, (7) Table swivel clamp screw (at front) and clamp not (under saddle), (8) Coolant distributor, (9) Table clamp lever, (IO) Longitudinal feed control lever, (11) Power fast travel lever, (12) Transverse feed control lever, ( 13) Trans- verse adjustment handwheel, (14) Vertical feed control lever, ( 15) Feed selector lever and dial, (16) Saddle clamp lever, ( 17) Knee clamp lever, (18) Vertical adjustment handwheel, (19) Knee oil reservoir sight gage, (20) Coolant reservoir cover plates, (2I) Compartment fitted for headstock change gears, ( 22) Coolant reservoir stainer, (23) Motor-driven centrifugal coolant pump, (24) Sight indicator for knee oiling system, (25 j Filler and sight indicator for oil reservoir in column, (26) Longitudinal adjustment handcrank, (27) Speed selector lwoer and dial, (28) Universal Spiral Index Centers headstock, (29) Spider for ~remrm ad1ustmer.t.

available provides for a wide variety of work, and an automatic table reverse makes it possible to rough and finish mill at one chucking by the use of dual feed rates if this is desired. This machine is adapted for climb milling as well as conventional milling.

Size and Power Rating of Milling Machines

The term “size” is generally used in referring to characteristic dimensions of certain main elements of milling machines, their range of movement, if in-

Figure 3

tended lo be movable, and the power rating of the main driving motor of the machine.

Thus the range of movement or maximum travel in the longitudinal, cross, and vertical directions of

the table, saddle, and knee, respectively, of a knee-

and-column machine (Fig. 4) and the corresponding movemenfs of a manufacturing machine (Fig. 5)

determine the physical dimensions of the machine and its capacity for doing work. An increase in the size of the machine is determined not only by the need for accommodating larger work, hut also by the need for more power.

Size is particularly important in the case of stand-

ard miZEing machines because they are designed to handle a variety of work. Rather than fit the ma- chine to the job, the work is assigned to the machine in relation to its capacity.

The power of the driving motor is selected in relation to the probable maximum cutting capacity required of the machine. The power is the same in all machines of a given size.

In the very low range of spindle rpm which is suitable ‘or heavy milling with large-diameter high- speed steel milling cutters, the power of the driving electric motor is automatically reduced to half that

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I- --d

Figure 4

in the higher range of spindle rpm. This range is that commonly used in high-speed milling with car- bide-tipped cutters, and the higher power available permits taking advantage of the high productivity of these cutters.

There is no definite size for special milling mu- chines which are designed for a specific job or opera- tion. The design of the machine, its range, and the power rating of the main driving motor are deter- mined by the requirements of the job.

Milling Machine Accessories

Attachments, Textures, and arbors are rcmovnble, supplementary devices or accessories made for the purpose of increasing the usefulness and productivity of the milling machine.

FIrttms are attached to the table of the milling machine and are intended for quantity production. They are designed chiefly for holding a specific piece of work while it is being machined, and are classified as special equipment. The design varies in relation to the type of work, the method of holding it, and the method of machining employed.

Attachments are of a more general and standard character. They are designed for application to the

spindle, overarm, table, and various slides of milling machines, particularly those of the standard type.

Figure 6 show:; the difference between a Exture and an attachment. The work is held in n fixture

Figure B

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designed for the purpose, and the fixture, in torn, is bolted on the rotary table of a circular milling attachment.

Attachments are divided into two classes, stand- ard and special.

Special attachments are made for the purpose of adapting a standard milling machine to special mill- ing operations in quantity production. They are used on a machine for an indefinite period of time which may be determined by a change in the design of the part or the method of machining it. When they are removed, the machine can be used for general milling work or, by the use of different special or standard attachments, it can be adapted to perform other milling operations.

Standard attachments are easily removable units for either temporary or semi-permanent application to standard milling machines. The large variety of standard attachments are as follows:

1. Attachments which serve as auxiliary spindle units, mostly connected to and driven by the main spindle of the machine.

2. Attachments for holding the workpiece on the table. Some are stationary; others are’ capable of im- parting additional movements, such as rotary motion or indexing the workpiece held between centers.

3. Attachments for mounting the cutter (arbors, collets, adapters, and others).

4. Attachments for precision measuring the adjust- ment of various slides of the machine.

Standard attachments are of particular v&z in toolroom work where a mil!ing machine may he re- quired to perform a variety of machining operations such as the following: cutting helical and spur gear teeth; profiling work on dies, models, and patterns; and other work requiring frequent changes in setup and operation. Standard attachments also find their place in quantity production where they may solve a manufacturing problem quickly and without re- course to special equipment. They reduce, to a large extent, the necessity for having a variety of differ- ent or special type machines by providing the means for handling different classes of. work and work in- volving a change in method on a single milling machine.

HEAVY VERTIC.~,-~MILLING .~TTACHMENT. By means of a vertical-milling attachment (Fig. 7) mounted on the face of the column and supported from the over- arm, plain and universal types of milling machines can be adapted to operations which are ordinarily done on vertical machines. The speed of the vertical

Figure 7

spindle is usually the same as that of the machine spindle. Angular surfaces can be milled by swinging the vertical head in a plane parallel to the face of the column and clamping it at any required angle be- tween zero and 45 degrees on either side of the vertical position.

HIGH-SPEED UNIVERSAL MILLING ATTACHMENT. The high-speed universal milling attachment (Fig. 8) is used on plain and universal types of milling ma- chines to adapt them to perform milling operations on surfaces in a wide range of positions.

The cutter may he placed in a vertical or hori- zontal position and at any angle in the plane parallel to the face of the column, but only within 45 degrees on either side of the vertical position in the plane at right angles to the face of the column, or a com- bination of the two. A quill hand-feed device pro- vides adjustment for the cutter. The wide range of the cutter adjustment is obtained through the com- pound swivel on which the spindle of this attach- ment is mounted. The attachment, supported by the everarm, has a limited lengthwise adjustment, and its spindle is driven by the machine spindle. The attachment spindle operates ate a higher speed than the machine spindle, and is designed for receiving small- to medium-size cutters such as are used in performing key-seating, die-sinking, and other opera- tions of similar nature.

UNVERSAL SPIRAL MILLING AITACNMENT, The oni- versa1 spiral milling attachment (Fig. 9) can be


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Figure 8

Figure 9, Universal spiral milling nttnchment set up for milling a large helix angle.

mounted on horizontal milling machines of both the plain and universal types. As in the high-speed uni- versal milling attachment, the spindlehead is mounted on a compound swivel which permits swing- ing the spindle in both the horizontal and vertical planes. It can then be clamped in the angular posi- tions required by the job. The speeds of the attach- ment spindle are the same as those of the machine on which it is being used. When a universal spiral milling attachment is used in conjunction with a dividing head on a plain milling machine, this ma- chine can handle milling operations similar to those performed on a universal milling machine. When a universal spiral milling attachment is applied to a universal milling machine, it will make possible the milling of helices having a helix angle of greater than 45 degrees on parts such as gears, worms, screw threads, spiral milling cutters, and twist drills.

SLOTTING ATTACHMENT. h4onnted on the column face of n plain or universal milling machine, the slotting attachment (Fig. 10) converts the rotary motion of the spindle into the reciprocating motion of the tool slide. Thus a milling machine can be adapted to perform work with a single-point cutting tool, similar to n slotter, as in the cutting of key- ways. The slotting attachment is valuable when a slotter is not available nnd on work for which a key-seating machine is not adaptable. The tool slide can be set at any angle through 360 degrees; the stroke from zero to four inches.

UN~ERSAL DIVIDING HEAD. The universal dividing head is an exceptionally versatile and accurate in- dexing attachment which may be employed to sup- port the work between centers (Fig. ll), or hold it

Figure 10. Application of a slotting attachment.

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A \

1 1

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\Vhel-e light strokes and less pressure are required, the thumb and fingers of the point-holding hand rnav change thrir direction until the thumb lies at riglit angles wit11 the length of the file, their position changing ::I I-cqtiired to increase the downward pres- suv i .4. Fig. 92 j. In holding tire file with one hand to filt, pins, dirs. smnll parts, and edged tools, which cannot be secured in a vise and which must be held in the other band_ the forefinger instead of the thumb is genes-nlll placed on the top of the file and as nearly- paml!el’witb the blade as possible.

The &tmal I-ocking movement of the hand and ixim \vonld cix,-v the stroke of the i3.e across the wxk i!l ;a curved !in& which would produce a curved SUI- f;xce \vhrre a level surfaw is desired. Therefore, for thr ~r~iid H3t filing, try to carr!; the file forward on ;it, nlmost straight line; changing its course just c,!,r!l,<il to prwent grooving the material (.4, Fig. !I:! 1. A \\~rc>~;s lnetbod of carwing the file is shown in Lt. iKis. 92. i Iiw too much prrssr~re is evident, the ;ril) is trw dcywratr_ the file is not being held level, tlw mutinr is curved. and a rounded instead of a q~xe smface will inevitabl:,, result.

hr of tire quickest ways to ruin a good file is to iist> tuo mi~cli or too little pressure on the forward

stroke. Different materials, of course, require differ- ent pressures, but, in general, apply only enough pressure to keep the file cutting at all times. If the file is allowed to slide over the harder metals witb little pressxe, the teeth soon become dull. If the twth are overloaded by too much p~‘essure, they are likely to chip or clog.

011 the reverse strokes, lift the file clear off the work except when filing on very soft metal. Even then, the pressure on the return stroke must be ex- tremely tight, never more than the weight of the file itself.

DHAW FILING. Draw filing is the finish filing which assures a perfectly smooth and level surface on a piece of metal that has been filed roughly to the size and shape desired. Since files are designed primarily to cut on a longitudinal forward stroke, a file with a short angle cut must never be used for draw filing because it may score or scratch the surface of the work instead of shaving or shearing it.

A smooth file is generally used for draw filinq and the work is secured in a vise. Hold the file in both hands with the thumbs on the edge toward you and the other fingers on the rear edge. Grasp the file firmly at each end as indicated, and alternately push


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Rivet Sets

Rivet srts nrr ~isrd to frxrn and drn\r riwts (Fig. %a). Thcv :LW rrracir of tcwi stce! a:~1 al-r ;waiiab!e iji a \ ;Iri;t)- of sizes. The clip-sh:lped IxJle in the hot- tcji;; of the too: is 1rsed to fwm ti:e fillishcd head of :c rivet. T!w ~CI~IXY hole is used to dl-aw the rivet. Tlw large holr i!i thr side is IISC~ to slnooth oirt tlw I,mrs that iire l~uwhl.d timu~h the in&d by the

rivet. Riwtillg !~mwduws detailillS thus me of rivet sets are give1 ill Cha!>. 7.

Hand Groovers


Soldering Coppers

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Figure 97.




The three types of :;ddcring coppers genernlly usd in the sheet mecal shop are the squiw point. hottax. and ~KK>~~:I~ i Fie. 98 ).

%.WARE Forwrm COPPER (Fig. 98). The square pointed copper is the type commw~ly used for all types of sheet metal soldering. To do the various soldering jobs in the sheet metal shop, the points of these coppers are sometimes forged to various shqes. Detailed procedures for forging and using soldering coppers are given in Chap. 6.

BOTTOM SOLDERING. COPPER (Fig. 98). As its natne implies, the bottom soldering copper is employed for soldering the bottoms of pails, tanks, receptacles, and similar articles.

ROWIPX SOLDERING COPPER (Fig. 98) This copper is used for soldering all types of metal roofing.

HANDLES (Fig, 99). Soldering copper handles are made of either wood or fiber, with a metal ferrule at the end where the rod is to be inserted. The ferrule prevents burning of handles when the copper is heated. Handles for roofing soldering coppers and other heavy coppers are usually equipped with a large metal flange at the point where the rod of the copper is inserted into the handle (Fig. 98).

Method of Attaching Hun&s (Fig. 100). To at- tach a handle to the copper, heat the point of the rod red hot. Push the heated point into the hole of the handle to a depth of several inches (A. Fig. 100). Qllickly remove the rod and permit it to cool. Then replace the rod into the handle. TII get a tight fit, st;ikv tht- end of the, handle \s’itb :: mnl!rt T.S shown at 13, Fig. 100.

Firepots and Blowtorches

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_-. r / caCM%W.APFNG VEIN




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vi “‘!‘I. I i.6

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capacity than the machinist’s or the bench and pipe vise and is usuall!~ clamped to the edge of a bench \vith i, thumbscrew. T!lese type vises car, be obtained witI, a mnrimwn holding capacitv \xving between 1 I/? inches and 3 inches. These. vises nornrallv do not have pipe holding jaws. ’

The bZacksmifKs oise (Fig. 106) is used for hoid- ing work that mart be pounced with a hew); ham- mer. It is fastened in a sturdy workbench or wall. and the long leg is secured into a solid base on the floor.

The tripe aise (Fig. 106) is specifically designed to hold round stock or pipe. The vise shown has :I cqxwity cf from 1 to 3 inches. One jzw is hinged so tlut the work cm be positioned and ;hen the jaw h1-o~~~ht down and locked. This vise is also used on :I. hrt~ch. Smne pipe vises are &signed to use :I sec- tic~11 of chain to hold down the work. Chain pipe r-i.ri,s range in size from l/S to 2 i!2 inch pipe ca- !>tlcit\ up to 112 to 6 inch pipe capaci:y.

111uu PHI.:SS H.+xD 1’1s~ (Fig. 1(X!. This vise, ill ~iillUll\ rwd for holding 5111.’ II piccrs of rn;.trri~d. ill wnjlllrtion with a I,lotor-powtl-ed drill p~wss. It is v!pCppvd with WWI-al sets of jaw blocks for holding irregular-shaped pieces.

Cnre of Vises

Keep vises clean at all times. The,\- should be cleaned and wiped with light oil after using. Never strike a vise with n heavy object and never hold large work in a small vise. since these practices will cause the jiw to become sprung or otherivise dam- age the vise. Keep jaws in good condition and oil the scwws and the slide fre,i”eIItlv. Never oil the swivel base of A swivel jaw joint, as its holding power will be impaired. When the vise is not in else, bring the jaws lightly together or leave a very smnll gap. (The mov:d~le jaw of a tightly closed vise may break due to the expansion of the metal in heat.) Leave the handle in a vertical position.

Safety Precautions

When closing the jaw of a vise, avoid getting an! portion of your hands or body between the jaws 01 between one jaw and the: work.

When holding hew\ work in :L vise, plnce a block of wund under the work as a prop to prevent it from sliding down and falling on your foot.

DO not Upen the jaws of a vise beyond their cn- pacity, as the mowble jaw will drop off, causing personal injury and possible damage to the jaw.

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eet eta~~~or~ng achines

\lnriv type of m:ichine arr used ia indnstri:il ~llrt;~l-\~l)l~~iilg shqx for sc;u;tl-ilbg. cnttirlg. fuming. ~1 itnpi:y. scaning, axd other operations. Some of th.sc. ~~iiwhirizs al-e oprmted bj; foot-power, and,/ol- 1,~ vlrrtl~ic Inotors. In certain industries, mwhines s~x~~~i~dls &~si~ned to manofxture specific article 111,’ iii<d ~15 iI ru!e, tticse ,n:ic ,hines are combinations uf two m HKW standard machines. For obvious rea- SOIIS. thew specia! machines cannot be described here.

Squaring Shears

Two gcn~rid tvpes of squnrin,g shears are wsrd in the sheet mrtal \vol-kshop: foot-powc,l- opclatcd :md motor driven. Sq?xuing shrars RX used for shearing, cutting. trimming. and sqwuing to required sizes, the large-sized sheets of tin plate, sheet iron, brass, copper. or alumixun that are delivered from the mill. .A.lthough some squaril;g shars will diffrr slightly in design and construction, the operations of all are similar.

FOOT-POX:ERED SQUARI~C SHE.*RS. The principal parts of a typical foot-poxvered squaring shear are shown in Fig. 1. Ail standa~-d squaring shears of this vpe are eq$pprd with hvo transverse T-slots on top of the bed for the +cmt and bevel gauges and a large depression in the center of the bed for necessary clearance ( Fig. 1). Two gradwted scales for setting gauges are located on the top of the bed (Fig. 2). The two extension arms are used for supporting the front gai~ge, which can be fastrued in +‘IC T-slots of these front brackets for making either stuisht 01~ anguiar cuts (Fig, 1). A special .xvel gauge fol making angular cuts is attached to the bed. The side gauges, located on each side of the bed, are uwtl for squaring the corners of the material, anti the back gauge, mounted cr. the rear of the sheal-s, is used whw cutting lawge sheets. Two blades are uwd ill

this machine: a lowe: blade that moves upward and an upper cuiiiug blade thai descends simultaneonsl! whrn the foot treadle is employed to force the cut- ting blades together (Fig. 1). The bolddowu is u dwble service part used both fw holding the metal in i’l:lce i111d RS a safr’ty g11”“d (Fig. 1 ), Fuot-po\r,~ crcd squaring shears are usoall~ used for cutting IneMs up to and including 16.gauge (US. Stand- ard j sheets in sizes Z,, 0 SO, 36, 42, and 52 in. Larger machines are available, similar in design. hut sliphtl! difffcwnt in constrwtion, for sizes ranging cp to 120 in. For cut&g mntelrials hrlvier than 16.gauge, pow- ered sqtming shears must he used.

Operulion. It is usual practice to insert material to be syuared or cut between the cutting blade-s frr;m the front of the machine. When it is necessan~ to cut short pieces from very long sheets that ordi- nnrilv would interfere with the operation of the foot treadle, the met-11 is ixerted from the rear. When the sheet is inserted from the rear. the front hed g;u~ges are employed. When the mntvrial to be cut is 13~~~ than tlrc, ir,d of thv m;~chilr~. the bt,d gauge is rhtvndrd ollt on t!lr frotlt brd gauge arms that arc: pi-ovidrd for this purpose (Fig. 1 ). When sqnxring aud tCmnling smliller pirces that do not interfere with the optwtiwr of the foot trcadlr, the nx$cl-ial is alw~vs insrl-tvd bctwwn the crtttiug Illadr fnnn the fl-m;t of the machine and thr work is gn~gcd to thr rtYtl!il-ed size 011 the bed, using either the short (II’ the long brd gange.


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tion to start with the cllt. Imrrt two piecrs of wrap- ping pprl- Iwtwevn the kllivcs. With paper hrtwren the knives. turn the flywhrel slo\+ and watch ewe- fully the clrarance of the kItives all the way across. Proceed to move the bed inwad, obsrrving that the knives arc the same distance apart at the start ot cllt as at the ertrrme other end. Now raise the, cross h~xtl tu the highest point as I)efol-e.

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b<~l adjusting scwws evmly at each end of the bed. Tat twh adjustment of bed mownrc-ut until the kiwi\ (‘5 start cutting paper.

If shtws will cut paprr at both ends and Iiot ill tiw crutrl-, tightrw the truss rod llllt Ir~catvd in the iciitc’r of the back part of thc~ CIVSS head. .-\l\v;~ys tuuk thv nllt clockwGse and about one-eighth of :I tlml. .After this adjustment. try cutting paper and i-f’prxt if necessary wtil papw cuts clean all the way il(‘WSS.

if paper should cut clcxn in the crntw and not at the u~ls, wverw the adjustment of the truss rod nut.

\\%a1 these adjllstm~res h~\-r 1~~11 ~~~~:~pletetl and J ou :w IKXIV to cut sheet metal, tighten the lrg wrexvir holding the brd to thr lv~gs and tighten the chrd rnlts providrd for the brd adjusting screws.

~\lW\ \ kwp oil h&s 0: lilbl-ic;ltilr,~ fittings clean .~lril fill;,<1 with a good lubricating oil 01 light gWW.

(;.+!j S(;rAHIxc SEIx.+ns. :In additionnl cutting ad- wnt.rgv gxinrd in the use of the gap squwing shrars sho\vt~ in Fig. 6 is that the construction of this tvpv of shears permits the cuttill? and squaring of sheets of vxviui: ltwgths and widths. It is limited onlv by the size of the gap or throat. These machines are :tlso xluipped with R slitting gauge. This garage (‘~111 be wed for slitting material iunger than the cutting bladrs of the machine.

Fo&powwed gap squaring machines are avail- ahlr for cuttin,? sheet up t(, and including 52 in. in lrugth, with an 18 in. gap or throat and a maxinmm capacity for cutting up to No. I6 gauge metal (U.S. Standard).

Opcmtion nnd Maintrnance. The general pl-oce- drnrs for the operation and maintenance of these machine al-e similar to those previously given for sqmring shears.

POWER GAP SQLXRIXG SIIFARS. The new type of power gap squaring shears shown iu Fig. 7 is avail- able in lengths ranging from .30 to 144 in. and in a varied range of cutting capacities. It is powwed by an overhead drive.

Operrrtion. Although procedures for the operati<,n of these shears are similar to those previmlsly given, it is sometimes necessary to makr additional cutting adjllstments prior to cutting.

These machines are usuallv delivered and ad- justed for cutting to the full length of the machine (Fig. 7 j. The nominal cutting length of the shear thus adjusted is somtwhat longer than the cutting





Figure 8.

length of blades when set for slitting (.4, Fig. 6). Cutting length should be dccwnsed when the shear is to be oscd for slitting long sheets (IS, Fig. 8).

Convenient adjustment is provided ou connection saews for this purpose. The most popularly used is shown in Fig. 9.

To lower or raise the upper knife, first loosen nuts “A” on both the left and right sides cf the shear. Twning connecting screw “a” in a clockwise direc- tion \ looking from the top) will lower the uppo shear knife. Turning screw “B” in the opposite di- rection will raise the upper knife. C;we must be used to make the adjustment on each side intermittent; not to make a large adjustment on one side and then OH the other, but a little at a time on .cnch side until the desired adjustment is obtained. The ends of the gate or top knife holder and the ways in the

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sidf ho~~sin~s are macbirrrd to piwvidt, trmn I:32 to 1 ,ti in. clearmcr between thim. and unlt~ss the gate or top k!life holdrr is raiwd 01 loiverrd uniforml~~ st wch end; the sheur or rake of the knives will b’e reduced and a binding of the gate iu the guides will r-rs11lt.

\Vhrw adjustmrlrt is m&. be sure to tighten nuts “‘4’; srirlrrlv Uli rach r1,d of thr shcnr.

This adj&tmr~~lt is of further \aluc iI1 that it al- lo\x;s $!-indizg dwvn the upper knife as milch as the tool &rl edge will permit, xvhile still miiiutaining full Ilominal cutting length of shear.

RN; AXD CIHCI.E SIX&S. Riq and circle shears are usrd tu cut discs or iinss. oi- for irregular cutting to a line; whri~ the clamping arm is removed or pushrr! hack out of the way. The type shown in Fig. 16 can al:w !P :rwd for slitting c,prrntions. The parts oi a tvpic;J modern ring and circle shen~-s are shown in Fi,i. 10. The\- xc either bald or power opcwitcd.

cutting light-gauge nrattGls. thr cutters should jut touch but llot rub agailet cnch other (Fig, 10). For l~c~;~v~-g;~r~~e material ( I8 gauge or hc,avier), the wttcw shwld bc s~.pxratcd slightly (Fig. 10). 111 tllis rl5lxv~t. qwcific dirwtiims for adjustmrllt of cut- ters giwu by t1w In;,Iluf;Katrlrrr of the uquipmtwt sl~or~ld be follnwed. 0n thr: hand machine. ndjust- mcnt is accomplished by means of thrraded collars on the !o\ver angular &aft, and on power she;xs of 16 gauge capacity and heavier, adjustment is KWIII- plished by means of lateral movement of the upper shaft ill the: sillnr mannrr.

The cil-cle xru~ is provided with a pair of clamping discs. The !o\r,er disc is pro\:ided with a center point and a wrtical adjustment (Fig. 11 )

In the typr of machine shown iu Fig. IO. thr front and war circle arm adjusting screws positioli thi. circle arm i2 I-rlatioll to the rutting head. If the, circle arm is improperIv positioued, tht, circles will:

1. Have a “r~Azd.o~er” rdg~~ if rcw circle arm adjusting screw is in too far.

2. Form an ellipse if front circle a~-m adjustinK screw is in too far.

The optimum position of the circle arm is between these extreme settings. Loosen the cil-cle arm cl~unp- ing screw when making adjlzstments. The upper clamping disc is lowered to a clamping position by means of a lever or hand wheel. This arm is also provided with two swinging gauges (Figs. 12 and 13) which may be set to center blanks and which are locked in place by means of setscrews. On hand machines. the circle arm is locked in place on its ways by means of a screw with a lever handle. On power ring and circle shears, the movement of the circle arm is accomplished through a rack and pin- ion; the circle arm is secured to the ways through the use of two bolts and nuts which can be loosened with a wrench.

Operation. When cutting circles, proceed as fol- lows: Determine the center of the square blank and prick punch the center point (Fig. 14). With a pair of dividers; scribe a circle of desired size 011 the blank. Scribing the circle can be eliminated if the graduated bed shown in Fig. 12 is used for setting thr sliding circle arm. ~,oosen the circle arm on its w:,v.; , c by rvlc;lsing the locking screw or bolts ~IK- vidrd. thm sliding it until it is in the proper position to cut thr disc requiwd. There is an indicator 011 the circle arm graduated in fractions of inches. Thcrrforr, if a circle 5 in. in diameter is to be ult. draw the circle arm hackward or forward so that tlw indicatnr on the circle arm is pointing to 5 in. on thr

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scale, then lock the circle arm secwely tbrougb the locking lever. Using the prick punch mark as a guide, place the square blanks between the clamping discs ill positi”” and clamp (Fig. 14). Tighten the lock- wt on the circle ari” to check that tbr cutters are in line with the previously scribed circle, then turn the blank by hand.

Lower the upper cutter a”d make adjustment if necessary (Fig. 15). Turn the operating handle on hand machines or switch on the power on power machines to cut the disc (Fig. 16). When the circle has been cut, release the clamping handle to remove the disc. If a quantity of the same size is to be cwt, the swinging gauges ca” be adjusted so that they will strike the edge of the square bla”ks and ceotel them (Fig. 17).

To make a ring, or to cut a circle from the inside of a sqr~l-e sheet of metal, the blank is cla~nped be- tween the clamping discs in the usual way and the sliding circle arm, with the sheet metal ~:ank irv serted. is brmlght toward the wttrrs, perlnitting as much of the edge of the sheet to slide between the cutters as is necessary, according to the size of the inside of the circle that is to be cut. \Vith the proper alignment of the blank in the machine secul-ed, bring the “pper cutter down on the material by twrGng th,e cl-ank screw hard enough that the critter-s will crlt the material without brlrring or bwklilrg the edge.

If a tendrncy to buckle or p”l1 a disc is “ctrd. it indicates that the center of thr clampi~ig disc is not pl-oprrlv located. The center of the cl.unq~i”g disc. whet, l”.qx~lv svt, is slightlv off centrr of the, \‘cI- tical cuter linr of the cut& on the side toward which the metal is fed. It is in line with the edge of the cut. This adjustment is made ~“1 ha”d nuchi”r~ b!; mriw of setscrews 0” eithrr side of the ways. 011 nxw~s of setscrews which rest :qinst the cil-clr wn to the slidr are loostwrd and the AH” adjrlstcd b! mw”c of srtscwws which rest against thr circlr awl c;istillg jttst back of thcz lo\wr clamping disc bewi”g. 1%~ thy prop~7 setting is mxle, thr bolts art’ lCKk,Yl ;,,rd “0 f,,l?hcr- adjrlstlnent except of the cut- 11v slwuld be rq~~irrtl.

TO \lit m;tt<.l-i:d ,II this machine. p~~~e~~l as f”l- ICNY St,t tllc, slittilig g;ulge to the wqlliwd width nl slit witI) iti rr~le as sl~wn i” Fig. 17. Set Abel c:ln~np the ,,,,lx’r c,,tt,.l- ;md proceed to makr the cllt as showIt ill Fig. 18.

I~W~~IIN wts can bc ma I: 01) this machine b> srtti”g and clamping the qpcr wttw, feeding the matwi;rl into the machine, XKI goiding the material with the left h:md so that tht. cutter will cut along the scribed line (Fig. 19

~ttli;icatiwt. Fx &icie”t operatio”, hand operated

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Figwc 16.


I:igl:ie Ii irrhr-v).

I’iprr 18 (right ). SLITTING A SIIEET ,”

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, K’?E’;i~!L,4R C’JTT I Nc, i

Figwe i9. To make the necess;t~y blxle atljustm:~tlts, blxle, ;ittaching screws are loosened atd the hrxdlcss set- scwws are tllrned urltit the pr-oper ctruance brtwet~ll the ?d;ides is att;~inrd. Thrli the blxlr Iruldi~rg SCI’<‘\\‘s arr tightened. This adjustment wilt allow the sheet to pass without any obstruction.

Operutinn. The hotddown attachment should be adjusted to hold the metal in the crltting operation and to prevent it from tipping up and wedging be- tween the blades. This adjnstmrnt is made by means of the knob screw at the top of the shenr.

SC.HOLL SHEARS. Scwtl shwl-s of the tyl,e shown in Fig. 21 art designed for cutting irregular shapes and for cutting inside of sheets.

The lower blade is attached to a slide which work:; in V-shape guides and is operated by the hand levw.

The slide is held in the frame by a cap which has hoiding and push screws for adjustment. This cap should be adjusted to hold the slide firmly without binding.

The upper blade is stationary and is attached to a plate which is adjrlstabte for lining up this blade with the lower.


.4djust the upper blade to the lower by loosening slightly the two cap screws holding the plate in the frame, and adjust the blade by the two adjusting screws back of the plate in the frame (Fig. 21).

Kerp blades sharp and property adjusted. For irregular cutting and inside cuts, tbe shape to

be cut is marked out on the blank. When cutting to the tine, best results are obtained by making short

Figure 20. cuts. The length of cot is controlled bv a check nut

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available in vuious sizes with working lengths r,ang- +;; Li:; 2: iii :,i ii I.2 ii.. ;orvrr iuldr~rs al-t! used or1ly fur IMSS production. Snivel-s;d adxptability and ra- piditv of oper;ltim~ ~n;tke bu folders the Inost ir- prtiill: ~nxbin6-s for slrwt IrrI:tal wwk.

A gmgr (Fig. 21) is pr~widrd fw IMWW or widr, folds. Stops fix the ;mgle of the bend. Adjustmvnt can be made fox sharp or rounded bends rcquil-ed for wiring. Thick or thin material may be clamped.

The rdge of the sheet is inserted under the folding blade and is automatically clamprd the instant the handle is pullrd upwal-d tcnw:.d t!;e opcrxtor. Ciamp- ing is n&tained while the continued motion of the Ir;11~1lr cmnpletes the bend. Clamping and folding in one motion of the opwnting h;rndle makes the bal foldri- higllly prodlicti\,c on duplicating work.

The jnrc:, reisrd by the clamping nwchnnism. grips the &et W&I- thv blade. It is ndjnst;lblc for various tbickursscs of nlnteri;d.

ThC! xinp, pi\.r)tr,d tn tlw folding ti;lr (Figs. 23 :uld 21). tni-ns \\Gth it to prodr~w tlrc, II~~II~ It is nd- justable by ii rack iud piniru nrecb;miwr fol- slxwp




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Figm 23.

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Figure 24.

or rounded bends. To facilitate inserting the work, ihe top surface of the wing is always Hush with the t,,p of the jaw.

:.ri:n~’ at either end of the folding bar are milled for ulilformity of pressure.

Stops detwnix the angle of bend. Two positive -tops tar 45 and 90 degree bends (Figs. 22 and 23) .,nd one adjustable stop are furnished. The latter, of split construction, clamps tightly at any desired angle ding.

The folding blade is special hard rolled steel, ac- curately ground all aver to an even thickness and Straight edge.

These component parts of a bar folder of the type shown in Fig. 22 are cica~ly indicated on the see- tional views, Figs. 22, 23, and 24.

Figure 25 shows the bar folder ready to receive the work. Te sheet, as shown, is inserted in the opening or ,pace between the folding blade and the jaw. It is held against the gauge with the left hand, while, with the right hand, the operating handle is brought forward toward the operator as indicated by the arrow (Fig. 26).

The jaw automatically raises (Fig. 26) to grip the sheet between it and the folding blade, holding it tightly while the remainder of travel of the folding


Figwe 25

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bar and wi~~g p~-~~doces the br~l. A stop limits thr arl-CW. thr folding bar turns on its tronnions, rotating nwtio:l of the folding bar wd tlrtcrmines the at~gle the cams. The high parts of the cams roll into posi- of the bend. tion on the cam rollers. raising the fotdixlg bar and

\Vhtv t!ic- optvating handle is wtrlrncd to its still-t- jaw and causing the latter to clamp the -shwt be- illg poillt. tll,, parts iiss111w thcil- original position twrw thr jaw alld the stationary folding blade. A ( Fig. 7.5 i. l‘his rrl~~~st~ thv clxlnping pr:ss~~~: 30 wutinwd motion uf the upelating handle turns the that thl~! fi!li\hCd \vwk call hr <JI’LickI~; and C%ISilY I(‘- folding bar ~IKI wing, forming the bend. The cams niOWd. maintain a constant clamping pressure on the sheet.

Tlx f!!!ditlv hlnde is I-igidlv fastrncd to the main ~1 Either of the positive stops can he set to limit the frsme. Thv jaw is piwtrd at ‘both ends :~f the ma- motion of the folding bar and the angle of bend. An chilw nt point :I. Fig. 2.5. it cxritas the two luge adjustable stop of split construction pivots on the left bwl-ings fw thr. TV-tmnions (R. Fig. 25). on which hand trunniw, and can be clamped for any desired t!w id&y bar tmns. A pkoted adjllstublc wing ir angle of beud. swtmttd on tlw foldiu~ bar and mows with it. The Clamping pressure or cleara~~ce for v,uiorls thick- i:~~ns 2: Imth C~IICIS of the folding hnr are conwntric nesses of metal is regulated hy raising or lowering \vith th(. tnlr~r~i~~lls. the cam I-oilers carried in the shrx~s. This is wxom-

(:;I!II 1011~~1~ art’ wrrird in t\vc shors at rithrr uul plished by mrans of the atijllstillg SCIYSVS shown in of t!lg, ili;~cl~in(! as itidic;itrd. T-he weight of thr fold- Figs. 25 and 26. illi: ij:fl~ :~wi j,iw assm~blv kwp n comtm~t pwsswe Sharp bends, such as those commonly required for ,I! t11,. r;i111\ ;ii:;iiilst the c:*~n rullrrs. lock seam. arc pl-educed whrn the wing is adjusted

‘i‘i~v lrnr pirt of the cam is in contact with the cam as show) in Fig. 26. Ro~~ndrd bends, such as are 10Ilt;r :I~ICY~ tIte in;lchine is ill thr opera or startity made when a wiw is to be inserted in the edge fox psitiiiil ! F’; 7- xq. -.> 1. .As thr opwatit,i: handle is p~~llrd stiffening, arc producrd if the wing is lower. The

wing is I-xised and lov~ered by it wrdge ndjustmrnt,


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which is actueted by a rack and pinioll nwchanism. Locking nuts are provided. Thr top of the willg is alwuys flush with the top of the jaw when the bx folder is in open or starting position. wgardlesr ~rf the position of the supporting wedges. This align- ment is obtained by a ::rlidr pin under thr wing.

The gauge under the folding blade (Fig. 2-l). against which the sheet is placed, is adjustable for various widths of folds by a large thumb scww. The setting is plainly visible on a scale graduated to six- teenths of an inch The gauge setting may be locked by means of a small thumb screw (Figs. 25 and OS).

The steel gauge bar. which has a series of gauging points. is mounted on n steel slide. The knurled ad- justing screw acts on the slide directly, without link- :!(:r or other mechanical elunents likely to wenr alld dri,eiop lost motion or inaccuracies. Spritlgs belw\ /!I(, saugl: slide keep the qarlge in close contact with <ht. rllldcrside of the folckng blade so that thr cdgr oi tilt, sheet to bc folded cannu: ox,rrride the gauge.

The width of folds that can be made on the bar il~i&l- drlxw~s upon the gauge of the material. Use the followitlg table as a guide.


Procedures for Basic Bar Folder Operations

!llAKISG SIYCLE FOLDS (Fig. % j. After squaring and cmttillg the nutel-ial to rrquil-rd size. the thwr

progressive steps for making single folds are: mark- ing the edge, folding, and complrting the fold, as shown in Fig. 28. The proccduw is as follows: hl;uk the sheet for the required width of fold (A, Fig. 28). Iooscn the locking screw (Fig. X), wt the g;lrl;e (Fig. 27), and tighten thr locking SCX-.Y. Plxr the, edge of metal between the folding blade and the jaw of the bar folder (Fig. 29). With one hand, hold the metal firm!y against the gauge fingrrs and place the other hand on the operating handle of the folder (Fig. 30). Keeping the hand on the sheet through- out the operation, pull the operating handle as far as it will go. Return the handle to its original posi- tion. Keep the hand on the handle until the wing is ill its original position. Remove the folded material. This completes the second step ( B, Fig. 28). Proceed with the third and final stt,p for making single folds (C, Fig. 28) by placing thr folded material with the fold facing upwards on the beveled part of the blade and set snugly agaixst the wing of thr folder as shown in Fig. 31. Pull the operating handle to flatten the fold, return the operating handlr to its original position and remove the material from the machine.



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Slwtx,: Dorvr.~ FOLDS. To make double folds (I’$ :32)_ proceed as follows: After squaring and xukirlg the metal, make a single fold as previously outlined, then insert the single folded edge between thr jaw and folding blade of the folding machine. To make the second fold (A, Fig. 32) and to com- plete the double fold (B, Fig. 3L), follow folding and flattening procedure previously given for making single folds.

make the first fold shown at A, Fig. 33 in the usual manner. After the first fold is made, insert the other edge of the second piece of sheet metal in the ma- chine and make the fold shown at B, in the same way. Connect both pieces and close the grooved lock with a soft-faced mallet.

UAKING FOLDS FOR GROOVED LOCKS OR SEAMS (Fig. 33). After squaring and marking the width of the grooved seam on the metal; set the gauge of the bar folder slightly less than the required width of the grooved seam. Insert the edge of the metal be- tween the fol.iing blade and the jaw, and proceed to

MAKING ROUNDED FOLDS FOR WIRED Ewxs (Fig. 34). Prior to making rounded folds or folds for wired edges, special wing adjustments must be made in the following manner: &love the wing back while it

Figure 30.


Fig,,re 31.



Figure 32.

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is idol in vcrtiwl position f, Fig. 33 ), and turn it hack SO tint the W:H of the bar fvlder is eli’o’ed. With :III qxv cud wrench, loosr~ the wedge lock-nuts (Fig. :3C j. Turn the ived~e adjmting screw and luwer the wirlg until the wedge is as faz- to the right as possible, thrn raise the operating hmdle to put the wing into a ve:-tical position. Procred ‘nv turnin;: the w~~lge ndjusting SCKW to set the wquked distmce hv!wcen

SET GAUGE TO i-iii x 0th. OF WIRE



- Fi:urr: oi.


I.O@SEN!NCj T!iF I.:!:‘::=~NUT.

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~ the \ving and the rdge of Ihe folding blade (Fig. ,35). For ;xop@r clearance this distance should be :Ibout 1 ::L’ ir:. more than the diameter of the wirt: Lo be used. !t can be checked easily by holding a piece of the wire that is to br used in the posit;on slwwn ill Fig, :3;. After checking tbc clearance, tightctl ttrr wedge lock-nuts; pl:tce the operating bandlr in its normal position. and proceed as follows: Squal-e the material and set the gauge to the diawter of wire ,::<I 11, as shown in Fig. 3-1. Place the edge of the mctnl bet\veen the blade and jaw of the folder. Hold the rmd lii-rnl~~ a+nst the gauge fin~el-s with me hand and puii the bandie iis far as possiblr with the other. Hr!n~:vt~ tbr folded sheet aft&r I-@turning the opwat- ing h;md!c to its original position.

~IAKIXG 43 DECREE, 90 DECRKE, OH SPECIAL AK;CLE Focus. The wing of tire bar folder must be set a? pwviorlsly described before rounded angle folds mav he made. For sharp folds this preliminarv procedure is not nccessarv. The \~ilrious t)-!ws of ‘;u~gle folds tllat cnn be made OII the hx folder are stlown in Fig. 38.

When 45 01 90 degree angles are to be formed, powed by moving the desired angle stop in place (Fig. 39).

When angles other than these two are to be formed, it is wcessary to set the adjllstable collar to produce the req~~il-ed angle. To do ttris, a metal tnn- plate cut to the deg:z of angle reqnir-ed is hrld be- tween the wing and the folding blade (Fig. 40). The adjustable collar is then set so that the stop just touches the frame and the gauge is set for the re- qrlil-ed width of the fold. Insert the sheet nnd pro- cwd in the usual manner.

Uuking Dodde Right An& Folds. .4fter deter- mining the size of right angle folds desired. xribe a line on squared material for the first fold sEown at A-A, then se&e a line for the second fold ‘j-E! (A, Fig. 41). If rounded bends are desired. the wing of the bar folder must be set as pre\%xlsly described.

Place the 90 degree angle stop in correct position (Fig. 39) and set the gauge to liw .%A. Insert the material and proceed to make the first fold (B. Fig. 11 i in the usnat rn~nw~. If several idaticnl pieces we to bc folded. make oil of these A.4 folds hefore proceeding with the second fold.


‘T - o complete the double angle fold, n-set the gauge to scribed line B-B, insrrt tbr material, and proceed to make the srcw~l fold ill the IISII~I man- ner (C, Fig. 41).

ANGLE FOLDS i’ .,-_,__-

Figure 38,

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Figure 40.




Figure 4;.

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Figrm 42.


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t’igurc 44,


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Pipe Folders

Yipr foldws (Figs. 43 and 46) we used in edging or forming locks on c:%:~dcl-s after the cylinders have been formr:i. The pipe folder shown in Fig. 46 has a capacity of *K;o. 22 gauge iron and lighter (U. S. Standard), and will turn a lock $i in. and $6 in. Locks of larger sizes, !,& ;,I. and j& in., can be formed by the use of lock increasing steel strips (Fig. 46). These are inserted under the work and between the Folding blade iFig. 46).

USING THE ?IPE FOLDER. To edge or form a lock on a cylinder, proceed as follows: Insert one edge of the cylinder between the fniding bar and the lip of the folding blade, and ciamp the work by moving thr hand lever to the left (Fig. 46). Pull the folding bar over toward you untiI the lock is completed (Fig. 45 j. Push the folding bar back and release the work by pushing the hand lever to the right (Fig. 46j. Form the corresponding edge by inserting the other edge of the cylinder over instead of under the folding bar (Fig. 46) and compIete the operation as pretious:y outlined.


\Vhen changing the gauge to secure ?,i in. and s/H in. locks, be careful not to turn in the gauge SCI’CW (9, Fig. 46) so far that it strikes against the folding bar. This will draw the folding blade out of line, By the same token the gauge screw (A, Fig. 46) must not be turned so far that it pushes the gauge and folding blade out of line. These two gauge screw (A and B, Fig, 46) hold or release a concealed gauge that is under the folding blade. ~he correct adjustment of these gauges is extremely important when the pipe foldw is adjnctrd for these two sizes of locks. When gauge screw B is screwed in and gauge A is unscrewed, the gauge is held up against the folding blade and will turn a 3’1 in. lock. When gauge screw B is unscrewed and gauge A is screwed in; the gauge is held down and will turn a +k in. iock. Before changing the gauge, push the hand lever to- ward the left as far as possible. After making the adjustments, return the lever to its original position.

Screws securing the cap and folding blades must be inspected frequently. If they are loose, tighten them to prevent springing the folding blade. Lubri- cate as directed by the r&ufacturer of the machine.

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[emailprotected],ON FOLDER AND BRAKE. --

Fi:r,,rc 4x.

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a lower jaw, between which the metal is clamped, are attached to the frame of the machine (Fig. 47). The bending leaf handles are used to move the bcntl- ing leaf, which forms the metal IO wquirrd fold LX farm ( Fig. 47). The beutling leaf is rrccssed to hold n 1,; in. steel bar (Fig. 47). This bar can be removed when making narl-ow, reverse bends.

The two clamping bar handles are employed tb move the upper jaw, which clamps or xleases the wl-k. E&I of these handles can be moved inde- pendently of the other.

To form curved shapes, molds (Fig. 50) are clamped to the bending leaf with the special friction &mps shown in Fig. 50. Molds are available in di- amrters ranging from 7,: in. to 3 in. Brakes operated by hand or powel- are available in various lengths ranging from 3 ft. I> in. to 10 ft. 1 in. ill cxpxities of mrxe than 1 ill. width bends 01 I~r;&rs.

Basic Operating Procedures of Standard Hand Brakes


Firm 49.

A standard hand brake of the type shown in Fig. 47 is usr~~lly operated by the mechanic from the right side of the machine. When operating a h;md brake, be sure that the fingers of the operator and the helper are clear of both clamping bars and bal- ancing weights.

Do not attempt to bend or brake more than a single thickness of sheet metal within the capacity specified by the manufacturer of the brake at any one time. \Vire, rod, band iron, or warned picu~s of metal must not be bent or formed on this machine.

Fill oil holes and lubricate all sliding surfaces at least once a week, using machine oil specified by the manufactwer. Strict adherence to these precaution- ary mea5ures is necessary to assure efficient and ac- curate performance of this machine.


PKELIMINAHY PROCEDURES. Before proceeding to make any sharp bends or brakes on this or any ‘hype of machine, it is important to determine and plan the proper sequence of braking operations. The rm- son for this is that sheet metal, irrespective of the type of metal used, will either be weakened or will dreak if it is hrnt up at a 90 degree angle or bent over square and then straightened and rebcnt in the opposite dirrctiori. This condition will wry in de- grce with the type of matwial used. The charactw- istics of th,: vwiolls mr~t:ils Ilsrd in tllo sheet Inctal iridllstj-y arc flllly drwrihd in Chap. 1.

- Fi<wc 50.

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F‘ig~rc 52.


Fictbrc 5%

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Figure 55.

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,,-is,i,r,. .33.

xl-t the pwviw:sI~ bent sheet, I-ele;se the clamping 1,:~ txu~dks. ins(.rt tl IV wwk, id dose both clamp- iy!; t,;u I~a~~dl~s (Fig. ~8). St;rlld i11 front of the t,r;tti<~, t,l;ic,~ both t~;~~rds on thr WI-~. awl txwd the


Figure 57.

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Combination Folders and Brakes

Combination fotdrvs of the type shown in Figs. 60 and 61 are availat)tr in sin5 ranging from RG ill. to 60 in. with wpwities v:u-ying frum I8 to 22 gnrlgr.

%ese machines are designed to fold locks ns tbr! ar 1 folded or bent on regular bar folders, and to .nake bends or brakes at any point on sheets as is done on brakes. They wilt also do a variety of other forming operations with the sheet remaining station- iwv as the bends are made.

‘OPERATING PIWWDUHES (Figs. 60 and 61). The ~lpper clamping bar with the folding blade is oper- ated by a hand crank through eccentrics and con- oectioas and may he adjusted for the various thicknesses of material by the hand sc~~‘ws on top of the side frames (Fig. 60).

.tdjust the bar so that the matvriat is bcld stc~uely when the crank is at its highest position.

The front gauges are used for forming narrow bends (Fig. 60). For wide bends. the rrar garage is used (Fig. 61 ). For bends wider than can be mndc with the rear gatige, scribe the shret at the point of

59). To ~CT~OV~ the formrd shrrt. reiensr hotb bend and bend CO the line.

clamping bar handles. in forming sharp bends or !ocks, the edge of the Remove &mps and mold with an upward blow folding bar should be even with the top of the bed.

of the mallet on the bottom of the cinmps. liounded bends or open locks for wire with a radius



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of not more than !i in. can be made by dropping the folding bar in the folding bar holders by means of the setscrew in the underside.

The adjustable stop on the left hand end permits the making of bends to the desired angle (Fig. 60).

The clamping b&r can be raised to 3 in. above the bed, and, by removing thr folding blade, will permit the use of special-shaped bars for special bending and forming (Fig. 61).

Two types of drill presses used for sheet metal work are the bench and floor types. The bench type is secured to the work bench in the usual manner. The floor drill press does not have to be secured to the floor, but can be set wherever desired. The floor m~ide!. however. should always stand on a level place in the workshop. The essential parts of a drill press are shown in Fig. 62.

The table m&t be readily adjustable for height over the entire range of the column, and should not have R tendency to become shaky or to spring when work is done up to the full capacity of the tool. It should be tiltable to any desired angle, and should he furnished with several slots for securing various fixtures and accessories to the tsblr. The table should

be sufficiently rigid to permit the attachment of a larger additional top required for various operations. It should be equipped with n device enablirlg it to be set quickly and accurately in any desired position.

The spindle of the drill puss should revolve in bearings that are entirely independent of those car- rying the belt pulley. If work other than drilling holes is to be done, the spindle must be easi!)- remov- able, so that other spindles can be substituted.

The head of the drill press should be reversible so that the tool can be driven from below the table, giving all the advantages of a separate shaper in con- junction with the drill press.

The drive should be as direct as possible, to pre- vent excessive vibration and ioss of power.

INSTALLATION OF THE UHILL PRESS. The instwc- tions given here fol- the ixlstallation, adjtlstment, anrl


Figure 62.

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operation of a drill press al-e applicable to all stand- ard types. Before making any adjustments, however, be sure to check the manufacturer’s printed instruc- tions.

The type uf drill press shown in Fig. 62 should be equipped with a I$ or !& hp, 1740 rpm ball-hew- ing motor, for efficient operaticn v&h any~ required accessory. The following speeds will be obtained: {I) With the spindle, motor, and pulley in direct line-580, 1300, 2440, and 5”OO; (2) xvi& the motor and pulley raised one step--760. 1800. and 4000; ( :3i with the motor alld pullet Iowered one step-1000, 1800, and 3300 rpm.

iiount the ,nutor on the motor bracket and place the p&~y on the shaft with the large step away from the mutw. With a strai$tedge, line up the motor p~~ll~v with t!w spindh puiley. The motor should ~-~rt;~tt, is) 2~ Arkwise direction wbe~r \-&wed from tiw pky end. If motor rotates in the wxmg direc- tion, i-rwrse its actiw according to manufacturer’s instructiorls.

.iDJ”ST?,“:KT” AS:D COUTKJL~. To move the drill- press ..c‘.Y ha--l or the tsb!r to R diiferent pociti!~llr on the column. Inosm the clamp bv turning the lcwr lo- cated nes: to the column.

The quill of the drill pl-rss is locked in prlsition by turning the small handle usuallv locatrd at the IOWPI front part of the hwd (Fig. hi). .I qui11 is a hollow shaft that revol\:es rm a solid shaft, curving pulleys or clutchrs. \i’htv chltcht~s are closed; &c.: quill aud shaft rewl\.r together.

The t\w krrurltd Iruts 02, t11c spindle stop gauge can be wt at HIIV desired positicn and Iwkrd. By rnearrs of this contr-ol. a definite amo,lr,t of spir&? trzvd can be obtained. and anv xumber of co~xec~~- tir-e h&s ca,! be dri!led to R d&it-rd depth.

with respect. Never strike it with a hammer, bump it, or drop it. Use no tools on a chuck other than the wedge or the chuck wrench.

When it is necessary to adjust the tension on the quill-return spying. turn the spring lousing cnrmter- clockwise to increase the tension, or pull upward on the ratchet-paw1 to release the tension.

To tilt the table of the drill press, pull out the knurled handle located directly beneath it (Fig. 62). If the table is tilted 90 degrees righi or Irft, the knurl pin can be inserted in the holes provided in the col- umn. For any intermediate angle the table must be locked in place by tightening the nut.

TOOLS ASD ~~IC~ESS~R~ES USED. The tools used for drilling, reaming, boring, counterboring, counter- sinking, and spot fxing are shown in Fig. 83. ,411 of these operations call he accomplished with either a straight-shank w tapered-shank tool. 4!1 rizcs of drills arId rear..ers under l/i in. are usually providrd with straight shanks which can be convenirntly and firmly held in the chuck of the drill press. The addi- tional cost of taper-sbnnk tools fo, these small sizes is therefoi-r no! necessary. In larger sizrs. the differ- ence in cost bt~twwn the straight and the talwr type is triHillg. It is always more convvnirnt to hold the,

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PARTS OF A TWI Si DFil LL ,-. --- _ m


larger .-:.a *n the drill press by means of the tape; shank.

Drillirzg is the operation of producing a circular bole b\, the 1~1nova1 of solid material. For this the ttcivt &ill is used (Fig. 64).

&or&g consists of both sizing and finishing a drilled hole. A reamer is a tool with several cutting ::dges (Fig. 63)

Enlarging a drilled hole by mums of an adjustable tool is called boring. A boring tool which has only one cutting edge is used (Fig. @3).

Cylindl-ically enlarging only the end of a drilled hole to a predetermined distance is called cotrnfer- hnrirq. The tool used for this operation is shown in Fig. 63.

A cotrntemink is used to form or cut a cone-shaped enlargement at the end of a prwiotlsly dl-illed hole, to form a recess for a Hatlrradrd SCI’C’W (Fig. 63).

A spot-facing tool is used for smoothing alltl squar- ing the surface around the ends of R prrviou~ly drillrd hole to seat a nut or the head of a capscrew.

Tools with tapev shanks ion small to fit tlie taper hole in the drill-press spindle .ue brid iI1 a special socket. The shank of this special sockrt fits into the standard spindle trolr. The attaclmwli ix c:dlrd a drill-pre,ey sock9 and ,c/eeoc (Fig. 6.5 i. Y’c:!t, ihxt tllr~ taper-shank sotkct and sleeve hns a ~!;i!twrrd end fwming 3 tang. This tang fits into a slot ai the end :)f the taper holr of the spindle awl lwlps drive the <lrill (the hold of thr taper alone is Ilot sltfficint j.

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- --

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O:hr: methods of securing the work al-e shown in Figs. 67 and 70.

L.o~/orrt of work. Use the following procedure for Iaviug out wol-k prior to d4ing: By means r~f iater- srcting lines, s!:i;w tlrr position of the center of the I& that is to be drilled. With a center punch, make a rli~ht mark at the point of these intersections. If tire work is rough, rub sclme cb,-lk 011 it. If the SW- her uf the work has beeli mac.rinrd or is smooth,


- Figure $0.


USC ii <ccatine of blvz vi:riol solution instearl <>f chalk. Let it rirv 101 a C’evi mint: es t before scribixg the SM- face. Using the punch mark as a center, scribe a circle with a pair of dividers indicating the size of the hole to be d?lled. Before proceeding to drill the Me, use a larger center punch to make a larger in- dentation at tire center.

SPEEDS AND FEEDS. Speed, as applied to a drill, is the speed at the circumference of the drill. This speed is ca!led the peripheral speed and is the speed at which the drill would trawl il’ i:: ~vere laid on its side and rolled. In other words, a CL ,. with a stated peripheral speed of 30 ft. a minute would roll a dis- tance of 30 ft. in one minute. Speed of a drill, there- fore, as generally used, does not refer to rotation per minute unless so stated specifically. As a rule, a drill does not pull itself into the work but I-equires a con- sta:lt pressure behind it to advance it. This advance is always measured in fractions of an inch per TWO- lotion, and is called feed. Feed pressure, therefore, is the pressure required in order to maintain the necessary feed.

The correct speed and feed are dependent upon so many conditions that it is impossible to give had- and-fast rules regarding them. They can be deter- mined only by judgment resulting from experience. The suggestions given should be considewd only a.s a glide and as a point from which to start npera- tions.

Starting Spee&. To start a drill, bring it dowu to the work by hand feed until it centers itself in the work; then, and only then, apply the power feed. As

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prwiously mentioned, no definite rules cau be given for the speed at which a drill should ru11 and the correct amount of fee+ per revolution. The compo- sition and hardness of material, the depth of hole req~~irrd, the lobl-iamt used, the type of machine used, the condition of the machine, the setup, point grinding. quaiity of the h&s desired, and many other items have a distinct influence on the speed5 and feeds required. The following speeds are given only as suggestions. The correct speeds and feeds should, as previously mentioned, be determined by good judgrnerlt and trial in each instance.


When the extreme outer corner of the cutting edges ot the drill \vears nway tao rapidly, it is evi- dence ot too much speed.

High speed in cast iron tends to wear away tlw mugin of the drill. The maximrun s]x~d s~:ggcstrtl for ccwbon drills in cast iron is 50 ft. per mirrlltc prriphwxl s]xxxl.

Stzrf irq Fords. The stxlting fwd is hugrly ,Q:““- wned 1~~~ the size of the drill asrd and the uxttc~rial to br d;-ilied. The ~eurr;d rule is to use a feed of ,001 in. to ,002 in. per rrvolution for drills snr:dle~ than $4 in.: IHI2 in. to .001 in. for drills ‘4 in. tu ‘\ in.; ,004 ill. to .Mi in. For dril!s 1, in. to !,2 in ; .oK in. to .()I,5 in. for drills 1, in. to 1 in.; 2nd .I)15 ill. to .?.j in. for drills larger than 1 in.

Start the drili with :I modwate spwd and a mod- vr;ltr twd. IIKW;IW c,ithcr 081~ 01 both after carc*f\ll ohwr\-ation of the* colltlition of the c!rill. The follow- ing suggestions siv~~ld be carefully ~J~srr\Y*d.

If thv drill chips out at the cuttilig v+. it is 3 cwt;ti:l iltdicxtiarz of <Gthw t<na tw;~vy a t<,cul 01’ ttrc~ rm~ch lip ~lr~;u;rnw. &~fr,,-c dr*cidilrg that it is tr>r> hr;wy n frwl. &cl, the, lip cl~w;m~~ of the drill. (See Chap 3 for dct;Gh:d dcscl-iption of parts of twist drills.)

.4 drill that splits up the web may have been given too much feed for the amount of lip clearance. Either decrease the feed or increase the lip clearance, or both.

Failure to give sufficient lip clenrance at the cen- ter of a drill will a!so cause it to split up the web. On the other hand, too much lip clearance at the center (or at any other point on the lip) will cause the lip to chip. Therefore, before blaming the feed. make certair; that the drill has been properly ground. If it has been properiy ground, decrease your feed.

It is bettrl- to err ou the side of too much speed than on the side of too much feed. This is true for all metals, with the exception of cast iron. The nature of this material permits an unusually heavy feed. Speed an be incvensed to the point where the out- side corners of the drill commerce to show signs of wwr-ing awny. The speed should thcrl he reduced Qhtly.

L~JBIWXTION FOR DRILLING. It is very important to use the proper lub;.-. *Gnt when drilling metals of gnrlgrs heavier than I;,,; in. Lubricants are used to coo] both the edges of t!~e tool and the work that is bring machined. Lubricants used for drilling are called coolants. As large n volwne as possible of the coolant should be dirrctrd onto the cutting edges of the tool, and nlluwed to flow onto and nrormd the work. Proper hzbl-icntion aids in chip cl~xance. It also mntr~ially improves the finish of the hole.

Suggested 1ubrical:ts for vorions metals MY: Alumimlm aud its alloys-Soluble oil. krr~~s~~e,

:md hwd-oil cwn]~o~~~~l; kwwx~~w ;md SIIIIIII!~~ oil mix- twes.

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Fiziirc 72.


Portable Electric Kand Drills

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[emailprotected]?LE ELECTRIC HAND DRILLS 143

?i 30 75

!!!,, XK! :30ti 400 300 GO,, X00



1x 18 18 18 I6 14 12 I?. 10 10

ii i

ix is 1X 18

j 1s 16

!6 1-I 14 I7 12 : 10 IO 8 IO I 8


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36267485 Metalworking Handbook - [PDF Document] (248)



All rll;lrllrf;*ctll~c.rs of st;~rId;~rtl plable drill:; fur- rlish detailed information on tlw limitations of ttwir tools. Do not mnkv the mirhkc of overloading; if the Ml stalls it is being seriously overloaded or otherwise improperly used. Never try to force a drill. Turn the switch off and rermwe the drill from tire work. Don’t click the switch off and on in an e&l-t to start a st:d!ed drill. This will ultimately damage the switch, overheat the motor, and may break the bit. To avoid stalling it is good practice to relieve the feed pressure as the drill bit breaks through the hisbed bole.

Y!IAIXTE,Y.~NCE~ AFW LUHRICATION. To maintain an &ctric drill in top operating condition, frwpnt iu- spwtiurn and c:~wfr~l atterttirrn to first sips of wciw im! wccssiq ( Fig. 84 )


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36267485 Metalworking Handbook - [PDF Document] (250)


Forming Machines

All forming machiri~~s arr similar to the genera! type shown i;: Fig. h7. They are made in many sims and capacities, the cxpacity depending on the dial+ eter snd length of the three forming rolls.

The two fl-ant rolls (Fig. 87) grip the sheet of metal and fmce it against the rear roll, which bends it rqnval-d arow~d thr rear of the front upper roll, curving the sbtet ;wd forming the cylinder.

The ream or forming roll can be adjusted in an angular vertical prGtion by adjusting screws 011 .the rear of left and right end housings (Fig. 89). Three inch and smaller diameter fwming machines have h;m~l adjusting screws, and on 4 in. and larger form- ing m;lchiner, the adjustiltg screws ahe fitted with sprockets connected with a chain for parallel ad- jllstmerlt of the rew roll.

For forming tapered eylindws, me end of the rear fmning roll can be adjwsted somewhat higher or

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\, ?



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Figure 89.

diameter of cylinder in sheet metal possessing more sprins or of sti!&r quality The adjustment of the

formed, so material will pass through the rolls freely

rear roll can best be obtamed through experiments when the hand crank is turned or power applied

with the materiai to be formed. (Fig. 87). Forcing the material through the gripping rolls without su&ient clearance for the thickness of

The adjustment of the hvwo front or gripping rolls is c .ined through a hand adjusting screw on each

meta may cause serious damage and breakage of

left and right end housing under each end of the left or right end housings.

OPERATING FOR.MING MACHINES. The sheet of metal lower front roll. The lower front roll is adjusted up to be formed is inswted from the front of the ma- or down for sufficient clearance between the two gripping rolls for the thickness uf material to he

chine between the two front gripping 1-011s after the two front rolls have been properly adjusted. Turn


Figure 90.

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36267485 Metalworking Handbook - [PDF Document] (254)



\Vhcw forming sn~:ll diamrter cylinders up to the full ratd capacity, it will be necessary to pass the mrtal through the rolls re\w;d times. After the rear roll is properly adjusted, the Grst pass forms a srmi- cylinder. The xar roll is t!xn wised somewhat higher and the metal passed through again. The rear roll is then raised to form the complete cvlinder. A little practice will enable the operator to betermine just how high the rear roll can he raised for the hrst pass and have the rear roll bend up the metal up ward. Three inch and larger diametrr forming rolls have longitudinal grooves in the rear forming roll to prevent slippage of the edge of the sheet against the rear roll and to assist in bending the metal up- ward. On these forming machines, the rehr roll is also driven, to assist in pulling the meta’ through the rolls.

On h eavy gauges of metal it is corn: ..~..i :rrai:icF to reverse the metal after the first p, Y., through the rolls when forming small diameter cylinders-to feed the edge of the curved sheet that passed through the rolls last in the first pass through the gripping rolis first in the second pass. This will reduce to a minimum the flat spot on the edge of the sheet after the initial pass, resulting from the space between the center of the gripping rolls and the forming side of the rear forming roll.

To reduce the number of rear roll adjustments in forming small diameter cylinders when working



I’i~m! 93.

light-g;mge mrt;tl, it is com1non Ixwticr to insert the edge of the sheet hrt\vwn the two fwd or grip- ping rolls from the front of machine. pinching the metal between the two gripping rolls and hending the sheet slightiy upward al-ound the top gripping roll, then continuing to pass the sheet thl-o~~~~h the machine by hand crank or power operation (Fig. 93). This will reduce the flat spot on the initial edge of the sheet to a minimum and will enable the opw- ator to form a cylinder of the desired diameter with fewer adjustments of the rear forming roll or in one pass through the rolls.

hlodern forming rolls of the type shown in Fig. 88, are of the slip roll type. On these machines the right hand housing is provided with a hinged journal cap and locking lifting latch, commonly called open- end forma (Fig. 88 ).

On these machines, at<< ~,: the cylinder is formed around the top front gripl:.,j;; roll, the latch is lifted, then the lever on the right end of the base of the machine is pulled down, lifting the top roll so that the work can he slipped off the end of the top roll without distorting the formed cylinder. The roll- raising lever is then pulled up and the top roll drops hack into its bearing. The hinged jour~xd cap is the11 dropped bark in position, the latch automatically locks, and the former is ready for the next forming operation. The roll-raising lever should never be forced down when the joul-nal cap and latch are in a locked position because this may distort the roll- raising mechanism, causing damage to the machine.

Forming machines are provided with grooves of

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36267485 Metalworking Handbook - [PDF Document] (256)








Figure 97.

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36267485 Metalworking Handbook - [PDF Document] (258)


L- Figire IC’.


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I:i~iw~. IOO.

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b”RR!UG P.te.CH’NZ. -~ - -..--~

Figure 108.


Figme 109.


Figure 111.

Figure 112. Figure 110,

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f .,f ott ~uqrr-s for s~~ppnrtir~~~ the disc :IS showr it) Fiz. t 19. 21~1 IWII tlw oprratiy liandl~~ I-xpid!v. ;illowi~~~ the disc to pas ti-r& thnxlgh thr band ~~~~~d I*‘oI the second pass. mis; the m&et-ial :lightlv. and at each suecrediug pass continue to raise the &sc until the edq:e has been burred to the reqrlil-txl position or angle (Fig. 114 1. The bmrinz of cvlinders is sim- iiar iu titat described for discs. with the mcrpti,>ll that the material is held in the position shown in Fig. 116.

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I’ipbw 111.

of the upper fact- against tlw upri$t rdgc. At this time, the small whorl back!; up tlrv netal, taking a position as shown in Fig. 118. By rotating the crank handle, the edge is deflected and is ready for flatten- ing. A turn of the hand wheel shifts the upper face so the flat portion of the upper roll will squeeze down the deflected edge as the crank screw is low- ered (Fig. 118), thus comp!eting the double seam.

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When !-ou start working with metal there are sev- wnl things vou nlwa~s have to think about before XIII em actuallv begin the work. Some of these are: nlaterials, Invotit ~xocedures. forming processes, and :~idi mrdri III other words, you have to know what !‘~III have to work with, how you are going to plan tlw job, how VW are going to do it once it has been piamed, and just what tools are going to be required to do the job.

Edges cmd Seas

S~~mir~rtg 01 joinii~g 7~ a* iiiij~~:f.::~i pwwss in the iabrication of sheet metal. The tvj,- :A w;im ;;nd method of joining are deprnderrt on the strxil, A~KI strebs the fabl-icated article must withstand. ;md ttw tools or equipment awilable. The \-ai-ious mxhinv tools used and PI-ocedures rmplo,x~d for the forming of desired bends o,- seams haye been described in other chapters. This chapter describr~s the procedrwcs for the fabrication of seams genewIly rwxl in the sheet metal shop where machine equipment is not available.

SINGLE EDGES. Single edges cw hems of the type


Figure 1.

shown in Fig. 1 are used in hemming the edges of sheet metal and in constructing single seams, They i,re formed either on R wood block or on a hatchet stake (See Chap. 3). The desired width is marked on the metal. The nxxteri;rl is then set on the block or stake and formed with a hall prrn hammer or mal- let (Fig. 2). The bar fo!c!er (Chap. 4) is wsed where machine equipment is available.

FOLIXD SUAZIS. Foldrd sc;ims are produced by tul-nitlg singie edges on the two picws of sheet metal that are tn he joi~~<~d. hooking thr ~dg<‘s fw@r~ its sbow~r ill Fig. 3, and h;xllrnrr,Aitg tlreln Hat with a


Figwe 2,

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F C) i “ E D 5 E 4 !;! :‘a0 S,NGLL EDGES

s j ,a ;,, i D Ti?JETiEi.

_--_.,--. Fi,Lprr 5.

the siwic eclw lws bw, frIC~,nr.d, the work is tur1wl O\,‘l ;,d thr smYd hrnd is mdr.

~:Hm)\i.:l) Sb:.A\ls. Grooved SCLI,TlS “1 !ocks of t11r type sh~~w~~ in Fig. 6 are usually led ill joining o! splicing flat pieces of shret metal, making vertic:d side se:uns in flal-ing or cylindl-ically-shaped articles. and making longitudirx~l seams in either square 01 wund she& metal piping. They are producrd hy hooking and offsrtting two fol&d edges (Fig. 3). 4s a g~r,wl-al rule. where machines are available the hr foldtl- (Chap. 4) is used for small articics. a:id the combiration or cornice brake (Chap. 4) for iq:rr work. \Vhere machines are not awilnhlr. grooved seams al-e f&l-icnted with a hand groo-rr ! Fig. 7 i. a grooving rail (Fig. 7), or a mandrel stakP (Fig. 8).

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Figure 9.

iI1 the two pircrs of shwt mc:t;ll mist be uniform ill width mid frMc.d or brut as sbow~~ at A, Fig. 9. The two pieces ilre: ttren hooked together and &set with the grooving tool as shown at W for an orltside seam, and h as s own at C for an inside seam.

When making grooved seams, be sore that the edges of both pieces of r?letal have been r-t s?:aigh: and that the necessary allowance drm-ibed in the fr~ltwing paiagraph has beer, mdr for the FCZ,~. Foid the edges scmt as shww at A. Fig. 4 and pull the foidrd edges together tightly before grooving.


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It is illrpur-t;+rtt to 1c5e a burxl grcro\cr or gwxing rail larger then the width uf the seilIn j. Eioldiq the tlmt is ,l:gl,tl!. largrl- than thr, sire of the lock. and groover in the left hand, plxe it over one end of tlr< tri use ii w~deri nrdlet to fastcvn tlw scam afta it i\ sc11m wd strike it with a han~mrr as shown in Fig. g*~lK,Wi. 10. Kcpeat this oprlation at the other end of tlrc

Ktyl~:l,,k:u t\i.l.“\IANCL;.S Km GHOO\-EE SEAMS. whell work. Start at the first point and proceed to groovr Ixvizig out pttf3ns for grooved seams, allowances by moving and striking the hand groove along the must be made foi- the metal used in forming these entire iengtb of the seam. The seam is finished by wtms. \Vhrn usilig 24 gauge or iigbter material it i\ Hattening it down with a mallet. WWWL~!~ to add three times the width (Fig. 9) of hlAKrNc AND FINISHING INSIDE GIWOVED SEAMS (C, the yrwi,,~ kick to the pattern 01 layout. Add one- Fig. 9j. Mark the edges, fold and form the job as h;df of thi> nlluw;~~wz to rech side of the lock. Wheu pl-eviously outlined, and proceed as follows: ~~~ivr 22 $:I 20 gaugr Inatrl-ial it is necessary to add .,- Select a grooving rail of the required size a1~1 tt,! 8’1. tiluw the widtll i Fig Y: uf the grwving !ock make sure that the width of the groove in the SC- ,,&< :;,,I, t;i,,c.i t!w thickwss d thr metal to the pat- lrctrd rail is approximately $$,; in. larger than the t<:n ,I! law it, G~,wrd wiims are rarely nsrd on width of tire seimi. Secnre the rail to the bench, hook ///,Al~~r/,ll I~\Wdiil~~ 20 ~<;iuge.

\I \h,TI, ,?.\,, F,xw\-~;~oi.lVIIJE c;Roovau SYAhlS tbc edges of the work together WICI plxe it on tbr rail. If the work is re:ct;u@ar ilk sllape, the war-k i\

7:ii~ IF!<, ‘!. Tu ~n;tke iud finish outside gwoved \C’.iiii p”‘.‘i i,s follows:

\ixik thy wdtii crf thr rdgrs to be folded on eaclr of t!rt: twu pirces to be joined arId fold them to the !-r;l,i!!xd xvidth. then term the job. If the wwk is cv- ii,lkd place it on a mandrel stake of the required cl:-\;itnre. if it i\ flat. place it on R flat stake or plate. Procerd to hwh the ridges together as shown in Fig. 2 ;d -!i$h Hetrn tl:e seam with a mallet. S&c! a 1r;tr:d groo\rr of the correct size ( iin in. or slightl!

placed 011 the b&turn part of tlu: rail: if cylindrical, the wwk is placed on the top or curved surface of tbr rail and the swm is held in the groove with the left hand. Using the other hand. strike an end of the se:nn with a mallet (Fig. 2). Repeat at the other end of the seam. PI-owed to groove the entire length of the seam by striking the work with the mallet evenlv along the seam. Strike it hard enough tu force thr folded metal into the groove. Hemove the work from the groove, place it on the rail with the gl-oovrd

Fiptre 10.

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seau~ in the position shown in Fig. Il. and finish or and similar sheet metal fittings to other parts with- close the seam with the mallet as shown in I?:;. E. out soldering or riveting.

PLAIN, Roui,-D. DOVET~UL SEAMS. Dowtail .sean~s The plain, round, dovetail seams shown in Fig. 13 ;we an easy rund convenient method for joining collars are made by slitting the collar, shown at A, with the

Figme 11.

Figure 12.

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ICE 6.7 SEAM- .-- _



Figure 13.

36267485 Metalworking Handbook - [PDF Document] (271)

combination shears to the required width of the tabs (B), and then bending out altrrnate tabs with a ball pee” hammer and a square stake, as sho\;w at C. These bent out tabs act as stops for the H:mpti or fitting. If a flange is to be fitted over the c&r, rut itn opening io tbr fhingc tbr six of the colkw. rlsil:s il pair of circular shows. (Sw Cba~~ :3. j To c mplrtt: the seam, place the collar with the notched :,nd beut- out tabs in the cut-out opening arxd bwel the re- maining tabs over the flange as shown at D. Flatten the stops by placing the Hnnge on a flat surface and hammering as showi at E, Fig. i:3.

The width of a dowtail is usuaIIy t in. The spac- ing between the slits ranges fi-om !r t, 1 in.? depend- ing 011 the size of the \r-ork.

if~atrrtight dovetail seams must be soldered. For dt?;tilcd wldcring prowdures see Chap. 6.

‘1‘o tx’i!itxte the rwn markinS of tab-widths 011 flw c~c:!l:kr; a rrralkirr!, 7 pr~;<c is used. which is III;& im!l :i piece of SC~;I~ f~ttt;d 31d ctit 0ttt to the pat- Frau showrl at A. Fig. 14. lbe owFh,Jd of using this gauge is shown at B.




Fipw 14.


Flangrs are bent edgrs made oo the edges of cy liudric;~lly-shap~.d parts (Fig. 15). The are used to provide :&lition:d stiffrning or to make connections to other sbwt mctol parts. Flnngcs of the type show in Fig. 15 are usually made with the torning or burr- iog mncbinr described io Chap. 4. Where watertight iiange connections are required, they must be sol- dered, using the soldering procedures outlioed in Chap. 6.

\Vhere turning or burring machines are not avail- able, or where &uges on irregularly shaped jobs are required, they cao be made by h&l.

When Aan~es are towed on the outside of jobs. as shown in Fig. 16. the metal must of necessity be stretched. Whtw Fur~wd on the inside of jobs. as showo in Fig. 17, the IneM is of worse shrunk.

In :tdditiou to the r-ivrting hemmer and rna&~F dr- scribed in Chap. 5, 1 IO I q,,wc and coodoctor tl : stakes, described in Chap. 2, are r~setl when Hnogiog edges by hand.

Twwrsc Oa~srrm FLA~XS. To form a flanged edge on the outside of a job, proceed as follows:

With the gauge shown in Fig. 14. mark the width of the required Hange on the inside of the job (Fig. 18 ) Note that the fiange shoold br nude as small RS possible. The reason for this is obvious, because flanging by hand requires the working or hammering of the metal. Excessive hammering will harden the metal and make it brittle. A large flange necessitates more hammeriog than R smaller one and will, in a great many casts. rrsult in cracking of the metnl.

Procced by placing the square stake in the bench plate aod holding the work with edge to be flanged in the position shown at Fig. 19. Strike the edge with the peen end of the hammer and revolve the work until the flaoge on the entire edge has been started.

As the flange forms and the metal stretches, lower the work gradually, continuing to hammer the flange with the peeo end of the hammer until the required angie is formed (Fig. 19). After the flange has been formed to the required angle, it should be smoothed on a conductor stake by holding the fiaoge oo the stake amI smoothing it with the flat face of the rivet- ing h:nnrncr, ns shown iu Fig. 20.

TUHNINC: INW>~: FI.ANCI.:S. To turn inside Ranges, procwd as follows: With the marking gauge, mark Fhv r~~qoiretl width of Fbe fkwgc on the outside of the work (Fig. 21). Place the work on a conductor

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36267485 Metalworking Handbook - [PDF Document] (273)

_ -- _,. - -

*:?I4 ;b-ic:, _ s

(OF any round stake of the correct curvature) with the edge to be turmd or shrunk as shown in Fig. 22, and strike rdgr with a mallet. When shrinking metal, it is advisable to use a n&let rather than a metal h:inmwr. to pwvfnt stwt&ing and buckling. Pro- crcd to rmdre the work until thr entire edge has been formed. Keep lrnwring the job and striking the edge until a flange of the desired angle has been formed.



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0 0 5 n c 2.

-.I II I !A 7. o- _

ll”Z ZrnGI

36267485 Metalworking Handbook - [PDF Document] (275)



i/Q 6,‘O 50 4:O YJO 2u !lJ


,i 7 h 9


11 12 1 3 14 15

16 Ii 16 19 20

21 22 23 24 25

16 27 28 29 30

31 12 33 ,3’S 3.5

38 3; 28 :9 40

.4615 A305 3338 a25 .:33:0 JO65

.I920 .IiiO .1620 .14x:3 .I350






.0625 .a,54o .I475 .MIO .034R











.0132 .OEZR .Ol !Y .(1IW .ows


.425 380 .249

.3OG .284 .259 .238 ,220



.I65 ,145 .I.34

,5QOO ,468: ,437s ,4062 .3i50 ,343; 3125

,261” 26.56

2500 .‘44 2187






x862.5 .E452 .Qsm .(wx .G:jY,j

.5800 .5165 .4600 .4096 .364R 3248

.a?93 .25;6 .2294 2043 .1x19

.I620 .1442 .1284 .1144 .101x

.QSQ: .116

.0808 ~ ,104

.a719 ~ .oso B640 .0x0 .0X0 ~ .072

.0508 ,064

.I’452 ,056

.a403 I ,048

.a358 ~ .040 a319 , .0:36

.fmL$ .(I32

.0%E ~ .O?X .@225 ,024 .WOL .I)22 .OhiY : .MO

,500 ,464 ,432 .400 ,372 ,348 ,324

,300 .276 ,252 ,232 ,212

,192 .176 ,160 ,144 ,128


BIP7 .0139 / .OPR Figure 24.

(ii72 0142 : .0164 (il.56 .OI% : .0148 allowance is as follows: twice the diameter of the

.@I40 .0112 ~ X,1:36 OE2.5

wire is added to four times the thickness of the mn- .IIPQo- ~ .0124 t&al used. An example of how this is computed is I . .

as tollcws: Material used, !/I,; in. thick; wire to be used, fi in.

in diameter (B, Fig. 24). ?‘J in. X 2 f v16 in. >< 4 = s in. Another method of determining the neressaly al-

tow:mce for wiring is to secure a small strip of the mnterial wed, and. with a pair of pliers, Ircrrd this mat&al closely aroood the win: (6, Fig. 24 ).

~~At.~~l~A~I~(~ ~~~U)~~~ IXNC.I.II OF Wow. The cs- tabtished rules and f~~~u?~s for ~~~~~~~~~II~ the tmgtb of wire reqrrired tcr wire the edges of circular. scpwm?. and recTtangolar jobs are as fdlows:

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~:ir~~nlor. The length of u-ire required for wiring L.W. = 4 1.’ 2o:i + 2 x ‘/4 the rdge of a circulars juh is rc4md to the dianwtw of L.W. =~z 81 1 :z = Sll,$ in. tire job 41lur tlw dianwtrr of thr wire multiplied 1)) Aaxc~r 811 x in. of wire required. Pi ( 7 ) UII;CII v1411;ds 3.1416. The formril;~ is ex- Rc~tmnprlor~ The length of wire required for wir- 1 ,ICI\CC ,I 0 ows: 1~. . 1 i: f ~11 ing the edge of a rrctangular job is equal to 2 times

L.\\-. == 7r ( 43 : d) the length of the j& plus 2 times its width and plus D = diamr:er of job in inchrs 2 times the diameter of wire used. The formula is d : dimwter of wire in in&es expressed a(s follows:



? i-1111-11----.J


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L.\V. =: 2 ;A: 21 + 2 >,, 9 -1~ 2 ;..: % l..\V. ::1 42 ,t, 18 + I,+ :‘~~ lw2 An5xxr 60’ L’ in. of wire recpiwd. Pxwct:in:w:s FOH FINISIIINC WIHED Exxs. All vdjirs

of shret metal al-ticks that are cylirld~ically-shaper1 witll straight sides (such as tanks, cans, and sirnilm jobs). md the smnll ends of taped jobs. are rmdly wired while the nutwinl used is in the flat slwet:




Figwr 30.

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that is, before the articles al-e formed. Boxes of var- ious shapes, hnx shaped articles, and the laxge rods of tapered jobs al-r usually wired after the metal has been formed to the required shape.

Where mnchirles are available, the edges al-e pre- pared for wiring 011 either the standard hncd brake or the bar folder (Chap. 4). and the edge is wired on the wiring nxwhine as described in Chap. 4.

Flat sheet edges prepared for wiring OE the stand- ard hand brakv and the bar folc!el- are shown at h and B, Fig. 28. To wire straight edges on Hat sheets where these machines are not availablr. proceed as fdlWW



Figure 32.

\\.‘ith a micrometer or wire gauge. measure the diameter of wire to be used and mark the edge to a width equal ta 2’; times the diameter of the wire. Bend the edge over as shown in Fig. 29. The con- plrted bend is shown at A. Fig. :30. (IlIt the wiw to the required length with wil-e Gppcrs or pliers,




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straighten the wire, and set it in the folded edge, holding the wire in place with pliers as shown at A; Fig. 31. When sheet is to be cylindrically furmed. it is necessary to extend the wire 1 to 2 in. from one t,nd to strengthen the seam as shown at B, Fig. 31. Still holding wire in place, start closing the fold with a mallet as shown at A and C, Fig. 31. Continue to bend the metal over the wire with the mallet as far as possible. The edge completrd up to this stage is shown at B, Fig. 30. Using the prtw of a setting ham- nwr. prmw~i as shown in Fi:g. .32 to complete the wired rd~c. A completed wired edge on a Hat sheet is shown at C, Fig. 30.

!WWII wiring au inside or outside radiw on a fat rIw<?. the procrdure is the same as that given above, with the exception that the wire must be rollrd in a x!is :;;!I foi-ming Imtchinr or shaped 011 a round stake to the required shape before inserting it into the tui-wd r.dge.

\Vtwn m.>king wired edges on flat material, always lock up the work with eithtst- a rail stake or a Hat pta!e. :md ;dunys USC pliers to hold the wire to avoid injwy to fingers.

‘iV&c FOR~XED RECTANWLAR OR SQUARE JOHS. To wire edges of formed rectangular cur square jobs, px!d a.5 follows:

Mark the width of edge on all four sides of the job equal to 215 times the diameter of wire. With shears, cut each corner to the width of edge as shown at A, Fig. 03. Fwm the edge with a mallet on :I suitable stake as shown at B and C. To ascertain the correct length of wire, use the formula given previously and cut to the required length. To form the wire to the shape shown in Fig. 33, proceed as follows. Set the wire in B vise with one or two inches of wire extending at one end of the vise (Fig. 34). Form this extended end of the wire to a 90 degree angle with a setting hammer (Fig. 35), measure a point in the wire for the following bends, and repeat the operation until the wire is formed to the re- quired shape. PIftrr the wire has been formed, place it ou the job and lay the job on a flat stake as shown at A, Fig. 36. Holding the formed wire frame in place with the pliers (B, Fig. 3fi), proceed to fold the edges with the mallet, bending the metal over the wire as far as possible on ali four sides of the job (Fig. 36). Bend the folded edges over as far as pos- sible on all four sides with the face of the setting hammer as shown in Fig. 35. Complete the job by pvening the metal edge c over as tightly as pos- sihle with the peen of the L :ng hammer as shown in Fig. 37.

Figure 35.

Fignrr 36.

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-- ,..-

Figure 39.

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Corners of quare or rectmgular jobs are usuall\; For edges of the type shown in Fig. 38, 21/b times solde,-rd ad filed smooth. iFor soldering procedures the diameter uf wire usd ‘. t I n UIMY on the turning see C!mp. 6. ) mnchiue described in Chap 4. To ascrrt;~in the

fV~ivnc Fwixrr;o T.~EWS:D Joas. To wire formed hqth of wire I-rquid, use the formu!a given pre- dpt:~~wl irh ;proi.t.~d ihh fdfows: viw51y. Cut thv wiw to the wpirrd tclrgth and


Figure 40.


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36267485 Metalworking Handbook - [PDF Document] (283)

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‘MACHINE TABLE Figure 50. molding work with step block and clamp for drilling.

close to the step ‘Ilock. This setup provides the most favorable mechanical advantage. As a rule, two or more cIamps are used on each setup.

If you are required to hold thin metal, place it on a b&k of wood to provide support directly beneath the intended hole. This support wi!l also help min- imize drill breakage when the feed pz~ssure is al>- plied. Secure the C-clomp (Fig. 51) and drill

!--‘!; iii. 49. step block am? dazaps. through the metal and into the wood. Stop drilling when wood chips appear, to avoid damage to the

i’i’ken hiding :t-ark with step b!o& and clamps, drill table. vou may use a gooseneck damp. as shown in Fig. 50. Currmc SPEED. The correct cutting speed for :Yo:e that the hod\- of the damp is approximately metal drilling depends upon the type of metal and parailel with the suiface of the drill press table and its properties, plus the diameter and type of drill that the bolt is held dose to the woik rather than (high speed or carbon). ( See Table 9.)




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I-rdtant thrend is known 3s a X r~r cent thread hcxm~se the diameter of the hole is 75 per cent of the difference between the major and minor &mm @en; subtracted from the major diameter.

\Vhen the top hole is the right size. it is a little lar!;er than !he root diumeter of the tap. its shown in Fig. .ii. The tap will rnt a thread in the work which is mah 7.5 per cent as deep as the thrr:td m the tap The &.l- “5 per cent of tlw depth of threxl 01, tht. rap p”“‘ides clearmwl~ Iwt\\r.en tllr. tap holr ;lrld tlw root dimwtrr of the tap ( Fig. J-1). This mdws tap- piiq easier.

If the tap drill selected is oversize. the tap hole will be oversize. and the tap cm cut onlv shailm threads in the work (Fig. 55). \Vith less t&n n full 73 pm cmt depth of thread. stud or capscrew threads usually strip.

Fknw ,4. I’rupvr Gze drilled hole for tapping.

Threads and Thread Cutting

‘/‘LLHI:~AD Z~~~IEXCL.~~TE The outside diameter of it t!lrwd is knowm as the major rliometer. The diam- rtii- across the roots of the thread is called the rnirw ~linmeter. TLe pitch i: defined as the distance from am point on the thread of 2 screw to the COT- responding point on an adjacent thread. It is ~ISIK& measured from crest to cwst and is expressed by a specific quantity of threads per inch. (, See Fig. 30. )

Fiaurr 52. Thread tcminology. TA,,,LL~ 1


Figure .i’3. Tap drill size detemi- nation.

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.nw .0595 .059i

“701) .07w




101s .l@la

.I065 .lIM


1495 :1594l

1770 : 1820

WI0 .2131

,257n .27w

3125 ,332u

.?a%0 .39l”~


.4531 ,4”43 .IISh

::4x (rw @7§

,766 RI25


.9375 .I_

Figure Si. Working drawing for tapping and cutting threads.

of tap drill to use. A similar chart is generally in- cluded with a set of taps and dies by the man- ufacturer. (See Fig. 57.)

Curring Machine Threclds with Tops

A 50-50 mixture of white lead and lard oil, applied witb a small brush, is recommended as a lubricant when tapping in steel. When using this lubricant, tighten the tap in the tap wrench and apply the lub- ricant to the tap. Start the tap carefully with its axis on the center line of the hole. The tap must be square with the surface of the work (Fig. 58).

To continue tapping, turn the tap forward two quarter turns, hack it up a quarter turn to break the chips, and then turn forward again to take up the slack. Continue this sequence until the required threads are cut. After you cut for the first two or three full turns, you no longer have to exert down- wwd pressure on the wrench. You can tell by tbe feel that the tap is cutting as you turn it. Do not permit chips to clog the flutes or they will prevent the tap from turning. If the tap will not turn, and you notice a springy feeling, stop trying to turn it. Back the tap up a quarter turn to break the chips, clean

Figurr 58. Iking a square to ascertain a tap is sqnerc with the work.

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I 1::;:,1 ,j’, i;~,,,< ii ,vi:i. it, chr Aips from nut<, “f B tap.

,/ i,ii:i!J 1 ,~ole vmi n+ll need al1 three types of taps- +&! +,i,~- .,.,ier. the phg. and thr l~ottoming taps. He sure th itx the size and thrrad sei-ies YOV need, and :1x1; thr, tap hole is the size called for bv the working dr;liviiiS illown ill FiS. .57 and Tabie 10.

Begin with the taptv tap. snd handle it as pre- viorislv dcscri!xd. -4. Fig. 60 slio\vs tile taper tap just starting to wt. In 1%. Fig. 60 it has cut 5 little farther. In C; Fig. 60 it has h!)ttomed ill t!w hole after ha\;- ing cut seveial full threads zwzr tiw Iup of the hole. Tiiis conrpIetc5 the wvr.;~k done wi?lr the tal)er tap.

111 .A. Fig. 61~ the pl\lg till> ~;IS entered the few full threads cut bv the tsper tap. in I!. Fig. 61 it has cow timled the ~threads a little farther down il:to the hole. In C, Fig. 61 it has i~ottomrd in the hole. This is all the work that !-ou c:m do with the plug tap. as it has wt full threads aboi~i haibay down the tap liolc hefore hottaming.

In i:ig. 02 tiw !xrttmning tap lms Iwm slblxtitllted ior the p111$ t;lp In A. F’is. 62 it Il:Ls lxwl n111 dowll the full threads <:llt I,\- tll<! ,,hl(: ,a,, and is I-wily t:, Cot mme fu!l tlrrcds. In 13. Fig. 62 it h;ls ult a few nmrc tllrrads, and ill c:. Fig. 62 it has Ix2ttomed in the hole. ‘1‘1~ I,lind Me hns no\v Iren complctrly tapped.

Rcc;~~:sc these thvcnds arc brin$ tapped it1 :L blind hole, c!lip rrurtnxl must Ix> tlont~ dilfvrcntl!~. ‘I‘0 rc- mow chips. hack thrl tap cornplctcly ant of the hole vcr~. frcqucntl!;. iril:ert Ilw stock, if pos.sil~lc, and jar out thr chips or work them out of t~lw 1~1~~ with ii wire wlrile the stock is ill the invrrted position: If the work cannot lx inverted, IAow out the chips with air. W71~cnevcr ~011 usr air, IN2 s,,rc to ,ISC safet\ gogglc~s. CZhil~ rrmoval in tapping I)lind holes is much more difficult to do and is wrv important lx- muse chips will f:IlI ahead of the tap tlrrou$ the flutes and accumulate in thr Ixlttom of the blind hole. Until these chips arc remowd. no~~c: of the three taps can complete its work. In tapping blind l&s, alternate with tnppiilg and chip rcmovnl until each of the tlll-ee taps bottom in the I,lind hole.

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.\ftrr using the three taps, brush the chips out of thei,- tcrth, oil them with lubricating oil, wipe off the surplus oil, and replace them in the threading set.

Cutting Machine Thxeuds with Dies

TO cut threads on a picce of round stock, first piid 2 d~i~fer on the end of the rod, as shown in I;;~. 57~ TImi hold the rod vertically in the vise to c~tt tlrc thrends. T!ic illustration calls for a l/2 - 13 N;ltir,nal Coarse (S.C.) - 1 thread. The 112 sig- iiihs dimwtcr and the 1G Ihe numlxr of threads per Irwin. I& figure 1 after the N.C. indicates that a c:lass i bt is required. 4 clnrs 1 fit is x IOOSC fit. The iit is c~~ut~~oilecl, while threading tlv round stock. Tap i!w thrrnds in the hole first, as there is no way to ;ii’jklst :I trl,. However, as threading dies nre usually adjust:ihl(-. control the fit of the threaded rod in the tuppt~l holr II? adjusting the threading die.

The xljuvtal~le round split die shown in A, Fig. 63 hns au ;Idjllsteble screw. i3y tightening this SCT~W znd sprr;lding the die slightly, it will cut less deeply into the I-od and the fit in the tapped hole will be tighter. The shallow hole (R, Fig. 63) is placed in the die stock opposite the adjustable handle (E, Fig. 63), and serves as n drive hole. Also, when the ad- justable handle is tightened, it holds the split die together and against the adjusting screw to maintain the setting while the die is cutting. The threads or cutting teeth of the die are chamfered or relieved (C, Fig. 63) to help start the die squarely on the round stock. The die is put into the die stock with the face of the onchamfered teeth against the shoulder (D, Fig. 63).

Figwe 64 shows a plain round split die and die

Figrm 6.3. Arwnhling an adjustshle round split die tg diestock.

Figure 64. Assembling a plain round split die to dies&k.

stock. At A, where the die is split, thex is no ad- justing screw. There are shallow h&s at B and C, on both sides of the split, opposite which there are setscrews in the die stock at D and E. In F, Fig. 64 is the adjusting screw which is pointed and enters the split A in the die. D and E are the holding set- screws. They have flat points and are tightened after the setiing is made with F. D and E hold the adjustment and furnish the drive as they enter the shallow holes B and C, as shown in Fig. 64.

Figure 65 shows a section of the die in the die stock and it: relation to the chamfer on the end of the work. The taper on the face of the die will accept the chamfer on the end of the work to start the threads square with the common center line.

To thread the work, brush some 50-50 white lead and lard oil on the rod. Start the die square with the work. Hold one hand!e with each hand, apply down- ward pressure, and turn clockwise until you feel the thread has been started. When the die has started to cut, rotate ,the stock two quarter turns, back it off one quarter turn to break the chips, and re- peat the cutting (Fig. 66). When you have cut enough threads so that the rod comes through the back of the die, remove the die and try the rod in the tapped hole.

figure 65. Position nf diestock in relation to chamfer CXI end of work.

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To cut internal pipe threads, drill a tap hole in the stock to be tapped. and following the suggested procedure for tapping machine threads as previousl! described in thiy chapter under the heading Cutting hlxhine -I-breads \rith Taps. rl,,, the pipe tap into the tap hole. Note that the first few threads on the pipe tap are ground away. This makes starting easier. Plenty of !ard oi! is th, 0L - -*andard lu’bricant fol sreel. Tap copper and brass with no lubricant. The depth to which it is desirable to tap pipe threads. is usually determined 1~); turning the threaded pipe into the tapped hole for a trial. As shown in Fig. 68: the lust fe\v threads on the pipe should still be vis- ible y.v!wn the pipe is drawn up tight in the tapped hole Figure 68 shows the Goes of dimension A (the length of thread on pipe I-equired to make a tight plint ) frr various sizes of pipe up to 13 in.

Tlw ~cwrw1 practice in tapping holes for pipe tlwads is to drill the proper size tap hole and then start the pipe tap right into the tap hole. Some wr~rkcrs recommend using a pipe reamer, especially when large, deep holes are to be tapped. A pipe xamer has the same 3/4 in. per foot taper as a pipe tap. .4 reamed pipe tap hole would have the same shape as the pipe tap, and therefore would make tapping easier and reduce wear on the tap.

Cutting External Pipe Threads

Usoally, both ends of a pipe are threaded with external pipe threads. (Note in all the illustrations showing pipe threads that they are V-shaped.) The standard 314 in. tqxr per foot of pipe threads is equrtl to 1116 in. per inch. Therefore, the taper of the threads on each side of the pipe is l/32 in. taper per inch. This taper cannot be changed, and this produces a tight joint. The angle between sides of the threads is 60 degrees, and sewrnl threads on the end of the pipe are perfect threads. The neat few

have V-bottoms but Hat tops, and the last few threads have both Hat tops and bottoms. Each size of the pipe has a certain number of threads per inch, built into the pipe taps and dies.

Adjustable pipe dies have a reference mark on each die which when lined up with the cor;;q~ond- ing reference mark on the die stock will give a standard-size thread. You adjust the dies one way or the other from the reference mark to cut a thread with the fit you want.

To cut external threads on iron pipe, first deter- mine its nominal si-e. Nominal size means the tuame size of the pipe, such as 118 in., 314 in., and so on. Except in the sizes below 1 in., nominal sizes COT- respond closely to inside diameters, For 1 in. pipe and larger, measure the inside diameter (I.D.) with your de, to the closest l/32 in., and you will have

‘ml size. For sizes below 1 in. voo can deter- nominal size by measuring the outside diam-

eter (O.D.) to the nearest l/32 in and reading the corresponding nominal size in Table 12. This method can also be employed for sizes 1 in. and above in lieu of the I.D. measurement.



To begin cutting, put the die siock or. the pipe SG that the pipe passes through the guide and enters the tapered face of the pipe die. Turn the die stock clockwise for right-hand threads, applying pressure only when startiq. It is not necessary to turn the die back and forth as you do when cutting machine threads. Pipe-threading dies can cut continuously be- cause thev cut only as many threads on the pipe as there arc on the die itself and because there is plenty of room in a pipe die for the chips to escape. After the die has taken hold, it will feed itself. When cutting threads on steel pipe, ;apply lard oil to the pipe and die where the cottiq is actually taking place. (Jontinuc twning until the end of the pipe has gone t!uoq!l thb I- die and is flush with the near face. (See Fig. 68. )

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Wns \r-i!i ;:iw \OI, till. length of thread called for i/! tlir t:thli. ‘i1mw in Fig. 69. Yore that in the liSSC!ili)l~d iI,li>? join! in Fig. 69 several threads re- main ou both pipe and Et&g to permit further tightmillg Fhdd it leak develop.

Reaming Operations

seaming operations are jobs that smoothly en- large &iiied holes to an exact size and finish the hole at the same time. .4 hole that has been made b> drilling is usually slightly oversize. This is quite sat- isfactory for holes in which bolts or rivets are placed. When greater acc~nw~ and a smooth finish are re- quired, the hole is first drilled undersize and then finished by wan&g. l<eamers are also {Ised to w- move burrs from the insides of pipe.

STRAIGEIT HOLES. .4 solid straight-bole reamer is used for most wrk, since it is the most accurate and rugged reamer. Tbe straight-hole hand reamer is turned by means of a tap wrench that is tightened on the square end of the reamer shank (Fig. 70). Se- cure the work in a vise so that the hole to be reamed is perpendicular to the top of the vise jaws. Position the seamer at tht top of the bole (Fig. 71). Straight- hcio reamers have a slight taper at the end so that they will fit into :he bole casilv. Turn the wrench clockwise 7 -;,- sl~w~ly until the reamer is centered in the hole.

After the rean er is centered in the bole, turn the wrewh clockwise with a steady firm pressure until the reamer has been turned all the way through the hole. When reaming steel, use cutting oil or machine oil to lubricate the tool. When reaming soft iron, do

Figure 70. Using a tap wrench to turn a hand reamer

not lubricate the tool. To remove the reamer from the bole, turn the wrench clockwise and raise the reamer simultaneously.

Note, turning the wrench too fast or too slowly will cause the reamer to chatter, producing an unevenly reamed bole.

TAPERFD HOLES AND PIN INSTALLATION. When in- stal!ing a tapered pin, be sure you have the proper size of pin to use. The size will be given as a num- ber and length in in&s. (See Table 13.) For in-



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I 2iamewr !

tSna!i i, End 01, j

Remet i

j 00497 : GGbli / 0,07?9 I LIOW? j 01021 i C8 1 : 3 i 1 a~1187 : o.i407 I 'Ii605 j Cl.?813 1 oearr , 02409 , 3,1745 i a31w ! 039i! j a 4805 a5795


Lenqth oi


4 7/ra 5 3/f6 5 ?;I6 6 13116

Cutting Piping and Tubing

The main difference between pipe and tubing lies in their wall thicknesses: Pipe has thicker walls than tubing. Though pipe cutters are larger than tube cutters. the\: work 011 the same principle.

PIPE. lkhre cutting a pipe to iength, Ix SUT~ you have the correct measurement. Figure 74 shows methods of measuring threaded pipe to desired k”f$lS.

-I-lit? edto-UK1 rnethorl inchdes I~nensuring the threaded portions of the pipe and mr:tsuring thr pipe from IW.I to end. Tlw cdto-center rneihotl is med on a section of pipe that has ii fitting screwed

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on one end only Measure from the free end of the pipe to the center of the fitting at the other end of the pipe. The center-to-center method is used when both ends of the pipe have fittings. Measure from the center of one fitting to the center of the other fitting at the opposite end of the pipe.

The approximate length of thread on l/2 in. and 3/4 in. wrought iron or steel pipe is 3/4 in. On 1 in., 1 l/4 in.. and 1 l/2 in. pipe the length of the thread is approximately 1 in. long. On 2 in. and 2 l/Z in. pipe the length of thread is I I/8 in. and 1 l/2 in.. respectively.

To determine the ler.gth of pipe required, take the measurement of installation such as center to centa of the pipe requiring two fittings. Measure the size of the fittings as shown in Fig. 74. Subtract the total size of the two fittings from the installation measure- ment. Multiply the approximate thread length by 2 and add the result to the length obtained. This will give the length of pipe required.

After the length of the pipe has been determined, meamre tht pipe and mark the spot where the cut is to he made with a. scriber or crayon. Lock the pipe securely in a pipe vise.

Inspect the cutter to make sure that there are no nicks or burrs in the cutting wheel. Open the jaws of the cutter by turning the handle counterclockwise. Position the cutter around the pipe at the marked point. Make sure the cutting wheel is exactly on the mark and close tb< iaws of the cutter lightly against

Figure 75. Cnttinp pipe with a pipe cutter.

the pipe by turning the cutter handle clockwise. After making contact, turn the cutter handle clock- wise one-fourth of a turn more. This will put a bite on the pipe.

Grasp the cutter handle and rotate the cutter as a whole one complete revolution, swinging it around the pipe in the direction indicated in Fig. 75. Turn the cutter handle clockwise one-fourth of a turn more to take another bite on the pipe and rotate the cutter another complete revolution. Keep the cutter perpendicular to the pipe at all times or the wheel will not track properly. Repat this operation until the pipe is cut. Remove the small shoulder on the outside of the pipe with a file and remove the burr on the inside with a reamer.

TIJRINC, Copper tubi-g is one kind nf metal!ic tttb- ing that you can cut readily with a tube cutter. To cut tubing, place the tube cutter with the cutting wheel on the mark where the wt is to be made. Move the cutting wheel into light contact with the tubing. (See step 1 in Fig. 76.) Then swing the han- dle around the tubing as you feed the cutting wheel a little for each revolution by turning the screw ad- justment. Different wall thicknesses, kinds, and diam- eters of metallic tubing require different feeds. Step 2, Fig. 76 indicates the direction of rotation. The feed pressure is correct when it keeps the wheel cutting hut does not flatten the tubing.

The design of some tubing cutters will permit cut- ting off n flared end close to the base of the flnre. Note the groove in the backup roller in Fig. 77. Place the flare in this groove so that the cutting wheel rides at the base of the flare. Then cut off the flare as you would cut tubing.

13urrs that form may he simiiar to those formed in

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pipe cutting. Remove the inside burr with the reamer ;ittnched to the tubing cut:er opposite the handle (Fig. 7X j, In some cases, R three-cornered scraper, pocketknife blade, or round file may work better than the ximw After ieaiiiiiig. c!ean out the chips. Then ~wnrove nnv outside burr with :I file.

Bending and Flaring Metallic Tubing

The objective in tube bending is to obtain a smooth bend without flattening the tube. Tube bend- ing is usually accomplished with one of the tube benders discussed in this chapter. In an emergency. nluminom tubing with n diameter of less than l/4 inch ma:< be bent by hand.

SPWNC BENDERS. External spring-type benders (A, Fig. 79) come in sizes to bend l/4 in., 5/16 in., S/S in., 7116 in., l/2 in., and S/8 in. outside-diameter soft copper, aluminum, and other soft metallic tub- ing. To bend tubing with this type of bender, first select the size that will just slip over the size of tubing you want to bend. Then slip it over the tub- ing so that it centers at the middle of the proposed bend. Grasp the bender with both hands and make the bend (B, Fig. 79). The restraining action of the bender wil! prevent the tubiq from collapsing at tht bend and will produce a smooth curve. To remove the bender, grasp the belled end and pull it off the tubing.

~nterd springdype benders (C, Fig. 79) are available in sizes to bend Z/i3 in., l/2 in., and 5/R in. outside-diameter tubing. This type can be llsed


Figure 77. Cutting tubing close to the base of a flare

Figure 78. Reamiug tht: hrrs from a piece of tubing

when both ends of a length of tubing are flared and the external type cannot be applied. To bend tobing with ;n internal spring-type bender, select the proper size bender nnd slip it inside the tubing. III- sert the bender so that the center of its length is at the center of the proposed bend. Grasp> the tubing with both hands and make the bend. If the bender sticks out of the end of the tubing, remove it by pulling it out. If not. remove it with ii fish wire or other simple menns.

HAW TURE RENDER. The hand tube bender (Fig. 80) consists of four parts-handle, radius block (mandrel), clip, and slide bar. The radius block is marked in degrees of bend ranging from 0 to 180. The slide bar has a mark which is lined up with the zero mark on the radius block. The tube is inserted in the tool, and after fining up the marks, the slide bar is

Figure 79. Brmding tubing with spring type tulle benders.

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Figure 80. Tube bending.

moved around until the mark on the slide bar reaclxs the desired degrees of bend xi the radius block. Follow the procedure shown in Fig. 80.

Thins type of bender is furnished in 3116 in., l/4 in., S/l6 in., 318 in., i/2 in. sizes. For Larger sizes of tubing, similar mandrel-type benders are used. The only dilierence is that these larger benders nw geared for greater mecbanicai advantn~r.

FLAHINC. Tube Haring is a method of forming the end of n tube into a funnel shape so that it can br held 1~~ a threaded fitting. A part~inlly threaded Harr nut is slipped over the tube, the end of the tube is &red, the flare is seated with the inside of the flaw

against the end of a fitting which has threads on the outside, and then the flare nut is screwed onto the fitting, pushing tbe outside of tbe Hare against the seating surface of the fitting.

The tube-flaring tool shown in Fig. 81 is one type which is commonly r~sed to flare coppe: tubing. To flaw the end of tobing, first clreck to see tbnt it bns been cut off s<pm+ and hs Ihe! bllrrs r-emoved from both inside and outside. I<cumnlwr to slip tbc flarc~ nr1t on the trr??e twfmx! y!!: make tt,c: hre. Threw xs shown in A, Fig. 81, open tbc flaring tool nt the die wbicb corresponds to the size of ttre tub- ing being flared. Insert tbe end of the tubing to pm

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(: !:::,~ !;ii$is,\ atiow tire top face of the die biocks. ‘~tjt; ,ir;~ot~at by which the tubing extends above the !~lc,ci:x detrrmines the i&shed diameter of the Bare. .i.!h hre mmt be large enough so that it will seat prq~~l~~ against the fitting. but md enough so that the threads of the flare nut ~~~11 slide over it. You &.termine the correct size by trial-and-error. Then, as sho\t:!i in BI Fig. $1 dose the die block and secure : -, the tool with the wiry nut. Use the handle of the >~oke to tighten the w;ng nut. when place the yoke over ttre end of the tubing (C, Fig. 81), 2nd tighten the handle to force the cone into the end of the tubing. ‘Fbe completed Ewe should be slightly vis- ihlr irt:ow the face of the die blocks.

Removing Brcken Bolls m‘d stuck

Wkn the removaI of a broken bolt or stud is re- quired; flood the part being worked on with pledty of penetrating oii or oii of wiDtergreen. Time per- mitting soak the mea for several hours or overnight. A week’s soaking ma>: ioosen a bolt which would otherwise have to be &i&d out.

1f enough of the broken piece protrudes, take hold of it with vise-grip p!iex as sbcwn in Fig. 82 and cart~f~dly try to ease it out. If the bolt cannot be t~~rrmi. further soaking with penetrating oil ma) i~t!p or. try remwing the pliers and jarring the halt with light tmmmer blows on the top and around the sides. This may loosen the threads so that the bolt can then be removed with the vise-grip pliers.

If rt iwIt has been broken off flush with the surface as shown in Fig. &3, it is sometimes possible to back it out with light b!ows of a prick punch or center

Figure 82, Removing a broken stud with vise-grip pliers.

Figure 83. removing a brokeu bolt with a prick punch.

punch. If the bolt was broken due to rusting, this method will not remove it. If it cannot be removed by careful punching first on one side and then on the other, a screw and bolt extractor (IS, Fig. 84) may remove it.

When using n bolt extractor, file the broken par- tion of the bolt to provide R smooth surface at the center ior a punch mark, if possible. Then carefully center punch the exact center of the bolt (A, Fig. 84).

Figure 84. Screw and bolt extractors for removing broken studs.

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194 WORKING WlTM METAL T.<s~r: 15


Extractor r- Size No.

1 2 3 4 5 6 7 8 9

10 11 12

..-__- __~..._.

overall Length, Inches

_-- -. 2 2 3:a 2 11/16 3 3 3/8 3 3/4 4 1/a 4 3/8 4 5/6 5 5 5/E 6 l/4

--__ ---- Used For-

See 7‘nblr 15 to .;elect the proper drill size to use according to the size of the broken bolt that you are trying to remove. If possible, drill through the entire length of the b&en bolt. Then carefully work some penetmting oil through this hole so that it fills the cavity beneath the bolt and has a chance to work its way upward from the bottom of the bolt. The more time you let the penetrating oil work from both ends of the broken bolt, the better are your chances of removing it.

When drilling a hole in a stud which has broken of? below the surface of the piece which it was hold- ing, as shown in A, Fig. 85, a drill guide will center the drill and may be preferred rather than a center punch mark.

When the hoie has been drilled, aud additional penetrating oil has had time to soak, put the spiral end of the screw and bolt extractor into the hole. Set it firmly with a few light hammer blows and secure the tap wrench as shown in B, Fig. 85. Carefully try to back the broken bolt out of the hole. Turn the ex- tractor counterclockwise. (This type of extractor is designed for right-hand threads only. )

A screw and bolt extractor can sometimes be used to remove an Allen head capscrew when the socket has been stripped by the Allen wrench (Fig. 86). When attempting this removal, carefully grind off the end of the extractor so that it will not bottom before the spiral has had a chance to take hold. B, Fig. 86 shows this end clearance. In doing this kind of grinding operation, great care must be taken to keep the temperature of the extractor low enough so that the tip can be handled with the bare hands. If

-.,,----~~--~ Nominal Screw And Bolt Size,


3/16- l/4 l/4 - 5/16 5/N- l/16 7/16- 9/16 9/16- 3/4 3/4 - 1

: 3/8 : 1 1 3/8 3/4 1 3/4 - 2 1/a 2 I/a -2 112 2 l/2 - 3 3 -3 l/2

-- -

Nominal Pipe Size, Inches

- _ _ _ _ - - - _ _ _ _ _ _ _ _ - _ _ _ _ I - _ _ _ _ _ _ _ _ _

I/4 3/8 l/2 3/4

1 1 l/4 1 l/2 2

Use Drill Size Dia., Inches

5/64 7/64 5/32 I/4 17/64 13/32 17/32 13/16

1 l/16 1 5/16 1 9/16 1 15/16

Figure 85. Removing a stud broken off belnw the surfxe.

the hardness is drawn from the tip of the extractor by overheating during the grinding, the extractor will not take hold.

REMOVING A BROKEN BOLT AND RETAPPINC HOLE. To remove a broken bolt and retnp the hole, file the bolt smooth, if necessary, and center punch it for drilling.

Then select a twist drill which is a little less than the tap drill size for the particular bolt that has been broken. As shown in Fig. 87, this drill will just about but not quite touch the crests of the threads in the threaded hole or the roots of the threads on the threaded bolt. Carefully start drilling at the cen- ter punch mark, crowding the drill one way or the other as necessary so that. the hole will be drilled iu the exact center of the bolt. The drill shown in Fig. 87 has almost drilled the remaining part of the bolt away and will eventually break through the bottom of the bolt. When this happens, all that will remain

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Figirc 6’. tir~movin~ a broken holt and retapping hate to same

of the bolt will be a threaded shell. With a prick pun& or with n suitable tool, chip out and remove the hst two or three threads, if possible, at the top of the shell. Then start a tapered tap into these sev- eral clea~t threads and continue tapping until the shell has been cut away and the original threads re- stored.

In GISCS where the identical size of capscrew or bolt is not necessary as n replacement. center punch and drill out the old holt with R drill larger than the broken bolt as shown in A, Fig. 88. Tap the bole first and then finish it with a bottoming tnp as shown in B, Fig. 88. Replace with a larger size capscrew or stud.

Removing o Broken Tap from a Hole

To remove n broken tap from a hole, apply pene- trating oil to the tap, working it down through the four Antes into the hole. Then grasp the tap across the Rats with vise-grip pliers (Fig. 89). Adding

A B Figure 88. Removing broken bolt and retapping hole to larger

Figure 89. Rmnoving a broken tap with vise-grip pliers.

Figure 90. Removing :I broken tap with a tap extractor.

penetmting oil as necessary, ease the tap out of the hole.

If the tap has broken off at the surface of the work, or slightly below the surface of the work, use a tap extractor to remove it (Fig. 90). Again, apply a liberal amount of penetrating oil to the broken tap. Place the tap extractor over the broken tap and lower the upper collar to insert the four sliding prongs down into the four flutes of the tap. Then slide the bottom collar down to the swface of the work so that it will hold t1.e prongs tightly against the body of the extractor. Tig’lten the tap wrench on the square shank of the extractor and carefully work the extractor back and forth to loosen the tap. It may be necessary to remove the extractor and strike a few sharp blows with a small hammer and pin punch to jar the tap loose. Then reinsert the tap re- mover and carefully try to back the tap out of the hole.

Each size of tap will require its own size of tap extractor. Tap extractors come in the following sizes:

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l/4 in., S/16 in., 318 in., 7/16 in.. l/2 in.. 9/16 in. 5/B in., 3/4 in., 7/R in.. and 1 in.

When n tap extractor will not remove a brokrn tap, try the following nletbod. Place n hex uut OVCT the tap (Fig. 91) and weld tlw nut to the tap. tie sure to choose a nut with n hole somrwbat smaller than the tap diameter to reduce the possibility of welding the nut and the tap to the job. Allow the weld to cool before trying to wmove the tap. When the nut, the tap, and the job have come to room tem- perature. it is often helpful to heat quickly the im- mediate wca around the hole with an oxyncetylenc torch. This quick heating expands th, adjacent metal d tlrv work after which the removal of the tap may

be less difiiadt. If the heating is too slow, the tap will expand with the adjwent metal of the work end thrw will be no loosening elfcct.



Figure Si.,IJ& a pln& weld to remove R broken tap.

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%ldaving is ihe process of joining two pieces of ilhe ur \llhlilw metals together by means of an alloy Irving ;I lower melting point tha.- that of the pieces I)tGrrz j9iilr,d.

PW strength of soldered points depends largely U~XK> the nature of the solder used and the tempera- ttli-e at \vhich the soldering is done. Therefore, the degzt: of strength required for joints must be kept in mind in choosing a solder for a given class of work. A large percenlage of soldered joints are de- fective due to improper cleaning and fitting of the parts to be joined. Seiection of the proper flux ! which is used to prevent and remove oxides) when necessary, is important. The m&J surfaces must he kept chemica!ly clean and free from oxide through- out the operation. If the base metal is one that oxi- dizes slowly, and if it is kept at the correct soldering temperature, it is usually sufficient to coat the freshly cleaned surface with tallow, rosin, or some other similar substance. For such soldering, the only re- quirement of the flux is that it should he present during the actual soldering process. If, however, either the metal surface or the solder is covered with an oxide film or coating, some method must be used to remove it. Most of the metal fluxes meet this re- quirement, thus enabling clean metal surfaces to come together and alloy. In soldering sheet metal parts that must be kept free from corrosion, rosin or some other noncorrosive flux should be used.

Soft and hard soldering are the two general classi- fications of soldering materials and procedures used. Soldering coppers (Chap. 3) are used for soft sol- dering and occasionally for aluminum soldering. Blow torches are always used for hard soldering, and often for aluminum soldering. Various types of soldering coppers are shown in Fig. 1.

I Because soft soldering is the type of soldering used

extensively by the sheet metal worker, the soldering procedures described in this chapter will be con- fined to that particular method.

The mest important points for the student to cm. sider in all soft soldering operations are: thorough cleaning of the parts to be joined, careful fitting to- gether of the parts, application of the proper flux, heating and tinning of the soldering copper, and ap- plication of the solder to the seam o: joint. The parts may be cleaned by scraping, filing, or brushing with a wire brush. This removes all scale, dirt, and oxides.

Figwe 1. Solrlt:rin~~ copperS. rap to bottom: regrhr, TO ing, bottom, and hatchet.


I 197

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in a chuck. It has an indexing arrangement as well as a gearing which is connected to the driving mechanism for the purpose of imparting such rotary motion to the work as is required when cutting helices. The dividing head is mounted on the milling machine table at the operator’s right when facing the machine.

The work may be indexed by any required portion of a revolution, thus providing a means to space notches and grooves on its periphery. These may be either straight (parallel to the axis of the work), as in the milling of spur-gear teeth, or at an angle, as in the flutes of twist drill and helicai mills, heiical and bevel-gear teeth, cams, and a variety of similar work.

Accurate spacing is obtained by means of a side index plate mounted on the dividing head, as shown in Fig. 11. This plate is made with a number of holes arranged in circles and equally spaced in each circle. Each successive circle contains a larger number of spacing holes; in addition, interchangeable plates with different arrangements of holes make it possible to obtain a wide range of indexing. Direct indexing for a low number of divisions is obtained by using the front index plate.

CIRCULAR MILLING AITACHMENT. The circular milling attachment (Fig. 12) can be used on the plain, universni, and vertical types of milling ma- chines. It provides rotary motion to the workpiece in addition to the longitudinal, cross, and vertical motions already available in these machines. It is bolted to the top of the tabIe of the machine, and can be driven either by hand or by power from the table-feed drive shaft. This attachment mounted on the table of a milling machine enables the operator to produce any profile-straight or curved-by using the table and cross feed of the machine and the rotary motion of the attachment. It is also employed in con- tinuous milling operations by using the rotary motion of the table as in the rotary type of milling machine. This feature is valuable in surface milling large numbers of small identical parts.

An indexing attachment can be used in place of the hand crank for work requiriug accurately spaced holes, slots, or grooves.

Figure Il. Dividing head mounted on the table of a universal milling machine set up for milling helicsl gear teeth.

Figure 12. Circular milling attacbnwk

MILLING MACHINE VISES. Vises are used for hold- ing the workpiece while it is being milled. They are bolted to the top of the milling machine table, and are provided with means to locate them properly with respect to the axis of the spindle. Vises are made in three styles known as the plain, the swivel, and the toolmaker universal.

The plain oise (Fig. 13) is the simplest of its kind. By means of tongues bolted on the under surface of the vise and engaging the T-slots of the table, it can be set with the jaws parallel to or at right angles to the axis of the machine spindle.

The swioel vise is identical to the plain vise with the exception of a swivel base under the vise body, graduated in degrees, on which the vise can be swiveled in a horizontal plane. The swivel vise is used for milling surfaces and boring holes at a given angle with respect to another surface or hole.

Like the swivel vise, the toolmaker universal vise is mounted on a base for swiveling 360 degrees in a horizontal plane. In addition, however, it is hinged for tilting in a vertical position, and may be clamped

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Figure i3. Application of a plain vise bolted to the table of a plain mibg machine.

at any angle between zero and 90 degrees. ARBORS, ADAPTERS, rn~ Cormx.s FOR MIWC

C~;~EPS. Milling cutters are mounted on the spindle- nose of a milling machine, or on arbors, adapters, or collets held in the spindlenose. These accessories are provided with various taper sizes for insertion in the milling machine spindkzenose. The main func- tion of adapters and coil&s is to extend the range of sizes and types of tapers that can be used in a milling machine having a hole of a given taper size in the spindlenose.

There also are quick-change collets and shell-end mill arbors which, used in conjunction with a special clamping assembly known as the quick-change adapter mounted on the spindlenose, make it possible to perform a variety of operations such as drilling, milling, and boring without changing the setup of the part being machined.

Fiiqm 14

The cutting tool used in milling machines is known as the milling cutter. It usually has a cylindrical body, rotating on its axis, and provided on the periphery with equally spaced teeth which engage intermit- tently with the workpiece.

Figure 15

Figure 16 Figure 16

Figure 17

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2. Tine teeth may be straight (parallel to the axis of rotation) or at an angle known as the helix angle.

3. Milling cutters may be made with a center hole for mounting on an arbor; integral with or mounted on a shank for insertion in the end of the milling machine spindle; or with the back recessed for bolt- ing directly on the spindlenose.

4. They may be made for either right- or left-hand rot&on, and with either right- or left-hand helix.

The bond of a milling cutter refers to the direc- tion of cutting, and may be determined by looking at the front end of the cutter when mounted on the spindle. A right-hand cutter requires counter-clock- wise spindle rotation; a left-hand cutter requires clockwise spindle rotation. These conditions are termed, right-had cut and left-hand cut.

The hand of the helilr may be determined by look- ing at the teeth or flutes from the cutter end. If they lead to the right, the helix is right hand (Figs. 14 and 15); if they lead to the left, the helix is ieft hand (Figs. 16 and 17).

Arbor-type milling cutters are made with either right or left helix. They can be mounted for either right- or left-hand cutting regardless of the direction of the helix. Reversing the position of the cutter on the arbor will change the direction of cutting to the opposite hand. Arbor-type milling cutters having straight teeth can also be mounted for cutting in either direction.

In the shank-mounted cutters such as end mills, the hand of the helix and the band of the cut can easily be determined by the operator by placing the shank of the cutter against his body and noticing whether the helix and the cutting edge lead toward the right or the left. If the helix leads toward the right, the helix is right hand; if it leads toward the left, it is a left-hand helix. Similarly, if the cutting edge is on the right-hand side, the cutter is right hand; if the cutting edge is on the left side, the cutter is left hand.

The same method can be used with face miUs and shell-end mills, holding the back of the cutter against the body and noticing whether the teeth and the

CLASSIFXATION, TYPES, AND USES. Milling cutters are made in many sizes and types for milling both regular and irregular shaped surfaces on the work- piece. They are classified as follows:

1. They may be of the solid type, with teeth and body integral; or of the inretied-tooth type, with re- movable teeth held and rigidly locked in slots or suitable holes in the body.

Figure 18

cutting edge Jead toward the right or the left. The four combinations of right- and left-hand helix

and right- and left-hand cut possible in shank- mounted milling cutters are illustrated in Fig. 18.

Cutters fall into two classifications: Standard milling cutters are those which conform to dimen- sions approved by the American Standards Associa- tion. The dimensional standards, relating chiefly to cutter diameter and width, size of center hole, and

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width and depth of keyway, have been adopted by cutter manufacturers.

Special milling cutters are those designed for work on special jobs. They may or may not have stand- ard dimensions and do not couform to any gener- ally accepted standard; therefore they will not be discussed in this book.

Standard Milling Cuttera

The many types of standard milling cutters may be classified as follows:

PLAIN MILLING Cwrr~ns. Plain milling cutters are cylindrical cutters with teeth on the circumferential surface only, and are used to produce flat surfaces parallel to the axis of the spindle. They are made in a wide variety of diameters and widths for “slab milling” operations, and may be grouped as follows:

Light-duty plain miIling cutters of less than ~~ in. in width generally have straight teeth (parallel to the axis of the cutter; those over Y* in. in width have the teeth on approximately a 25-degree helix angle. These cutters are useful in taking light cuts, but they have too many teeth and insufficient chip space for average milling work.

Heavy-duty plain milling cutters (Fig. 19) are


Figure 19. Milling of forged steel part with il heavy-duty plain milling cutter.

made in larger widths only. The teeth have a helix angle greater than 25 degrees and ranging up to about 45 degrees. Heavy-duty cutters have fewer teeth than the light-duty type and also are termed “coarsetooth milling cutters.”

As the name indicates, heavy-duty plain milling cutters are designed for applications in which a considerable amount of stock must be removed. Be- cause fewer teeth are used, the spacing is wider, providing ample chip space and permitting greater support to the cutting edge.

Plain milling cutters with helix angles of 4.5 to 60 degrees and higher are called helical mills. They may be of either the hole type or the shank type. Shank-type helical mills (Fig. 20) can be used to advantage for milling intermittent surfaces in con- tour and profile milling. Shank-type helical mills with pilot (Fig. 21) arc commonly used for milling elongated slots through the workpiece and also for milling wide surfaces.

The helical mill is efficient for taking light cuts on soft steel or brass, but is not as efficient as the plain milling cutter for deep cuts in slab milling, although it provides smooth cutter action and a good finish on the milled surface. This is a particu- larly desirable characteristic which makes shank- type helical mills valuable in profile milling.

END MILLING C-as. End milling cutters are solid-type cutters with teeth on the circumferential surface and one end. All styles except the shell end mill have a straight or tapered shank for mounting and driving. They are used for facing, profiling, and end milling operations. End milling cutters are made ixi three general types, grouped as follows:

End mills (Figs. 22 and 23) are multiple-tooth cutters with straight or helical teeth like those in plain and helical mills. They are used for light opera- tions such as the milling of slots and the profiling and facing of narrow surfaces.

Figure 20. Standard shank-type helical mill.

Figure 21. Standard shank-type helical mill with pilot.

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Figure 22

Figure 23

Figure 24

Figure 25

Two-Zip end miZ.?s (Fig. 24), also known as slotting miZZ.s, have two straight or helical teeth on the cir- cumferential surface and end teeth cut to the center. 1n milling grooves, this type of ciltter can be sunk into the material like a drill and then fed lengthwise in the groove. A depth of cut equal to the diameter of the mill usually can be taken from solid stock.

Shell end mills (Fig. 25) are solid multiple-tooth cutters without shanks having teeth on the face and periphery. The face is recessed to receive a screw- head or nut for mounting the cutter on a separate shank or stub arbor which is driven by keys on the spindlenose. Driving slots across the back of the cutter are engaged by drive collar keys on the arbor.

The teeth are generally helical in modern shell end mills, with either a right- or left-hand helix.

They may also be cut straight (parallel to the axis of rotation), although more efficient and satisfactory operation is obtained with the helical tooth form. Shell end mills are used to advantage in face milling operations requiring the milling of two surfaces at right angles to each other.

SUE MILLING CUTTERS. Side milling cutters have teeth on one or both sides as well as on the periphery, and are made for mounting on an arbor. The various types are classified as follows:

Half-side milling cutters are used in face milling operations and other applications where only one side of the cutter is required. Half-side mills have either straight or helical teeth on the circumference and one side only. The periphery of the cutter does the actual cutting and the face does the sizing and finishing. The length of the side teeth on half-side

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mills is greater than on the standard side mill. These cutters are efficient for taking heavy side milling cuts.

Slide mills (Fig. 26) are comparatively narrow cylindrical cutters having teeth on both sides as well as on the periphery; they are used for cutting slots and in face milling operations.

StraddZe milling consists of milling the right- and left-hand parallel sides of the workpiece simultane- ously. Such operations can he performed with either the half-side or the side mi3ng cutters mounted to- gether on an arbor with one or more spacers between them. When using the half-side mills, it is necessary to use one right- and one left-hand cutter. Cutters used in this way are referred to as “straddle mills.”

Z@d3cking slotting cutters consist of two cutters similar to the side mills but made as a unit with interlocking teeth. Interlocking cutters are used in preference to staggered-tooth cutters because of their flexibility. The cutters can be adjusted to the required width by interposing collars or shims. This also nxakes it possibie to compensate for the changed dimensions resulting from wear and sharpening. Interlocking cutters are effective in accurately sizing slots of shallow or medium depth. If the slots being milled are narrow, however, and the cutters used are consequently thin, the tendency of the cutters to “close in” will result in an undesirable change in the width of the slot.

Staggered-tooth milling cutters (Fig. 27) are nar- row cylindrical cutters with alternate teeth of op- posite helix angle. To reduce the possibility of drag- ging or scoring the work, the side portion of the teeth is relieved by leaving a narrow land near the edge of the teeth. Staggered-tooth milling cutters are used for keyway and other slotting operations. They have a free cutting action, even at high speeds and feeds, which makes them effective in milling deep slots. However, their use is limited to slots of narrow width, and the interlocking type of cutter is to be preferred for wide slots. In the solid-type staggered- tooth cutter, the width will change through wear and with each resharpening, thus altering the width of the slot.

METAL Srxrrm~ SAWS. Metal slitting saws are thin, plain milling cutters with the side slightly re- lieved or “dished” to prevent rubbing or binding. They usually have more teeth for a given diameter than plain milling cutters, and are made in widths from ‘/ia to 3/1a in. Saws are used for cutting-off

Figure 26. Slide milling cutters, straddle milling both sides of a reverse shifter bracket fur an automotive transmis- sion (sample of work shown at right, on top of fixture).

Figure 27. Standard staggered-tooth milling cutter.

operations and in milling deep, narrow slots. For heavy sawing in steel, metal slitting saws are


Figure 28

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made with staggered teeth and also may have side teeth simi1a.i~ to side milling cutters. Such saws usu- ally range :‘.I width from %o to 3/a in.

Special saws with form relieved teeth, sharpened by grinding the tooth face, are sometimes used for cutting copper and other similar materials. The teeth are given considerable peripheral clearance, and they are so constructed as to break up and throw out the chips, preventing clogging of the saw to a great extent.

When considering speeds and feeds, metal slitting saws are in a class by themselves. Because of their fragile section, they should be operated at approxi- mately % to ‘,b of the feed per tooth used for other types of cutters, except in cutting nonferrous metals, when the speed and feed can be much greater.

It is preferable, especially for thin saws, to use driving means other than the standard key. A de- sirable mounting utilizing tinges is shown in Fig. 2s.

ANGLE MILLING Cux-r~~s. Angle milling cutters shaped like segments of a cone are used ior angular milling-cutting of dovetails, grooves, V-notches, serrations, and reamer teeth. They are designed in . .


Figure 29

two general styles: SI!:g?e-angle cutters (Fig. 29) have teeth on a

conical surface at an angle of 45 or 60 degrees to the plane of the face. In most cases, the face is also provided with teeth.

Double-angle cutters (Fig. 30) have V-shaped teeth with both conica! surfaces at an angle to the end faces. The two angles are not necessarily the same. They are usually made with an included angle of 45, 60, or 90 degrees.

T-sto~ MILLING C~TIEX. The T-slot milling cut- ters are special purpose shank-type cutters (Fig. 31) for milling the wide groove at the bottom of T-slots after the narrow upper groove has been cut with a slotting mill or end mill. Straight or staggered teeth are cut on the circumferential surface and on both sides. Large ‘Mot cutters are made for monnt- ing on a separate shank.

WOODRZIFF KEY MILLING Currm. Woodruff key milling cutters are small standard keyseat cutters which are similar in design to plain and side mills. Sizes up to two inches in diameter are made with a solid shank for mounting in the spindle; the larger sizes are made for arbor mounting. The smaller sizes have straight teeth on the circumferential surface only, with the sides slightly relieved for clearance. The larger-diameter cutters are made with staggered teeth on both the periphery and sides. Woodruff key

Figure 30

Figure 31

Figure 32. Shaped profile cutter

milling cutters are especially suited for blind cuts such as in milling semi-cylindrical keyways on shafts.

I?CJRMEEI MILLING CUTTERS. Formed cutters usually have a curved-tooth outline, and are used in milling contours of various shapes. They may be divided into two classes; the shaped or formed profile cutters, and the form or cam relieved cutters. They can also he classified as profile-ground and face-ground formed cutters, according to the method of sharp- ening. Shaped or formed profile cutters (Fig. 32)

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have an irregular shape or profile, but in other re- spects they are similar to plain milling cutters. They may be of either the solid or inserted blade type. Their use is limited to simple outlines or profiles due to the d~ifficulty of maintaining the accuracy of this profile when the cutter is resharpened. Shaped profile cutters are resharpened by grinding a small land back of the cutting edge like that in plain mill- ing cutters. This means that the contour of the cutter must be reproduced every time the cutter is re- sharpened. There should be no difficulty in ac- curately reproducing simple geometric profiles like those in cutters of the plain milling type, but the grinding of a shaped profile cutter having a com- plicated outline may be difficult, and can be done more cnsily oo the cutter contour grinding machine shown. To obtain the necessary accuracy, gauges of the pro& should be made. In addition, a template for guiding either the cotter or the grinding wheel wiil often be required to secure the desired accuracy and speed in the resharpening operation.

Form or coon relieood cutters are ~of the solid type. They are so-called in contradistinction to shaped profile cutters because the clearance back of the cutting edge is produced by a form or a master tool in a cam relieving machine, giving all the teeth the contour of the master tool. Whereas shaped pro- file cutters are sharpened by grinding the land along the profile of the tooth, form relieved cutters are sharpened on the face of the tooth, thus preserving the contour of the original profile produced in the manufacture of the cotter. Form relieved cutters may be resharpened many times until they have been ground to a point where the teeth are too slender to withstand the strain of the cutting load. The teeth of form relieved cutters may have a radial face (zero rake), or may be made with a rake angle or “under- cut.” They may also be either straight (parallel to the axis of rotation) or helical. The helix angle is gen- erally five to ten degrees. As in profile-type cutters, the helical tooth form produces a gradual engage- ment of the teeth with the work, thus reducing shock and the tendency to “chatter.”

In some cases, form relieved cutters are made with an angular gash. This type is easier to sharpen than cutters having the teeth formed on a helix, but it is practical only on narrow cntters. Straight-tooth cutters are used for standard production work when the finish is of secondary importance. Helical-tooth cutters produce a superior finish and have a smooth cutting action which permits higher speeds. Formed cutters are osed for the accurate duplication of vary ing outlines or shapes, and make possible economical


Figure 33



__- --- -- El _-- --

Figure 31

Figure 38


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milling of complicated contours. Typical form re- lieved cutters include gear cutters, chain and sprocket cutters, convex and concave cutters (Figs. 33 and 34), corner rounding cutters (Fig. 35), spline and thread cutters, hobbing cutters, and others which, through wide usage, are now made with standard dimensions.

FLY Curr~ns. The fly cutter (Fig. 36) is a single- point cutting tool applied to an arbor. The cutting edge can be made in any desired shape. Fly cutters are used mainly in the experimental shop and tool room.

INSERTII~.TOOTH MILLING Currrms. Almost all types of milling cutters can be made with inserted teeth. bxhxletl are plain milling cutters, end mills (Fig. :37), sidr mills (Fig. 38), face mills (Fig. 39), shell end mills, and slotting mills. This type of conshuc- tion is pencrally applied to large cutters although it is also used in milling cutters as small as two inches in diameter. The object of the inserted-tooth con- struction is economy in the first cost as well as in maintenance. These cutters are made with a cylin- drical body of low-cost steel, an important factor in cutters of large dimensions. Grooves or slots are cut into the body for inserting the cutter teeth or blades. This makes it possible to replace the teeth quickly or adjust them to compensate for wear. It also permits using different materials, such as high- speed steel and sintered carbide, as the conditions of the job may require. In addition, the inserted- tooth construction prevents the loss of the entire cutter due to accidental tooth breakage because the damaged tooth or blade can be readily replaced. Various types of inserted-tooth milling cutters are as follows:

Face milling cutters are the most commonly used cutters of the inserted-tooth type, and are effective for facing wide surfaces. In sizes up to six inches in diameter they are termed shell end mills and are mounted on tapered shanks. Larger sizes are called face ariZ2.s and are mounted directly on the spindle- nose. Face mills are made in light-duty and heavy- duty types. Tbe light-duty face miII has a lighter body and a larger number of teeth, being used principally for finishing cuts. The heavy-duty face mill has a stronger, heavier body and fewer blades and is employed for heavy roughing cuts.

The general practice is to obtain the desired quality of finish and accuracy by one cut wherever practicable. This eliminates the additional time in- volved where the operation is performed in two cuts, known as roughing and jinishing cuts. The combin- ing of two cuts in one is sometimes applied to face

Figure 37. End mill with inserted blades.

Figure 38. Application of inserted-tooth type half-side milling cutters, performing a straddle milling operation.

Figure 39. Inserted-tooth type face mill with sintered carbide tipped blades.

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Figure 40. Slab mill with inserted blades.

Figure 41

mills having blades tipped with sintered carbide ma- terial. The roughing and finishing blades are mounted on the same body, with a limited number of finish-

ing blades set to a smaller diameter and extending slightly farther from the face than the roughing blades. They also have a wide face to sweep the milled surface effectively.

Face mills with blades of cast-tool material are used for milling steel, cast iron, and nonferrous ma- terials at a speed somewhat faster than is practicable with high-speed steel blades. Face mills tipped with sintered carbide cutting mate&& are run much faster than face mills with blades of high-speed steel or cast-tool material, and may be used for milling steel, cast iron, and nonferrous materials.

ZnseTtzd-tooth slob mills (Fig. 40) are long, cylindrical cutters of large diameter. The teeth are inserted in helical slots in the cylindrical body and are held in place by wedges and screws.

Notches known as chip breakers are often provided on the blades of these cutters, spaced so as to break up the extreme width of the chip into smaller seg- ments of more convenient size (Fig. 40). Where wide surfaces are to be milled, however, it is preferable to use cutters made in short, interlocking sections (Fig. 41).

SOLID MILLING CUTTERS wrni BRAZED-ON TIPS. Milling cutters are also made with the cutting ma- terial in the form of tips brazed directly on a solid cutter body. Inserted blades are thereby eliminated. These cutters ere usually made with fewer teeth than cutters of high-speed steel. This method of mounting the cutting material offers the advantage of greater rigidity and better performance as well as higher economy resulting principally from the con- siderable saving in the time required for main- tenance.

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peruting Milling Machines

With some milling machines, the machinist may stand either to the left or to the right in front of the table (Figs. 1 and 2), whichever is more con- venient for the work under cut. The machinist has at hand, in either position, all cortrols necessary for the operation of the machine (Fig. 3). As a further aid to operation, the table movements on the type shown ig the various illustrations are always in the direction the controlling lever is thrown, and, from both operating positions, as a general rule, a single lever is within reach to stop all machine move- ments immediately.

setting up

METHOD AND c UTTERS. The two important factors, to the successful milling of any job are: the choice of the method to be used, and the selection of the type of cutters to be used. Each is dependent upon the other, to a degree. However a third factor must be taken into account, the matter of feeds and speeds. A feed and speed must be selected, tentatively at least, before any analysis of methods and cutters can he made.

Whatever cutter is used, it should be of as small

Figure 1. Left operating position. F’igure 2. Right operating position.

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Figure :3. Operating Controls and principal parts of a r.ertic+l milling machine. (A) Machine start-stop Irver, (B) Scale for angular setting of spindle head, (C) Spindle feed handwheel and adjustable dial. (II) Swiveling spindle head, (E) Spindle stops, (F) Spindle skew clamp lever, (C) Spindle head clamp bolts, (H) Spindle head vertical alignment lever, (I) Adjustable co&m& distributor.

a diameter as possible for economy in cost and to avoid unnecessary “run in” allowmxes. Figure 4 illustmtes the relative “run in” required on large- and small-diameter cutters.

ARBORS. The cutter arbor seiected. if one is used, should be of as large a diameter as possible to get maximum rigidity. The use of too small-diameter arbors is a very common fault, and, unfortunately, their weakness is often emphasized by inadequate supports. If the stocks of cutters on hand make the

r-G 4

Figure 4

use of small arbors necessary, care should be taken to procure cutters, when replacements are made, lzge enough to permit the use of substantial arbors.

When an arbor of the proper size has been found and inserted in the machine spindle, the cutter should be mounted as close to the column of the machine as possible, and, if a helical or spiral cutter is used, it should be rotated in such a direction that, as the teeth enter the work, they tend to push the arbor toward the spindle rather than pull it away. Cutters should be securely keyed to the arbor because fric- tion from tightening the arbor nut cannot be relied upon to hold them. Spacing collars and the arbor nut must be perfectly clean before clamping because dirt or chips between a,ny of the members on the arbor are sure to cause a spring when the nut is set up, and, consequently, the arbor will run out. This not only prevents accurate machining, but causes uneven cutter wear, needless stress upon the machine, and severe wear in the bushings of the arbor yokes. On most arbors are hardened and ground sleeves, larger in diameter than the regular collars, that are used as bearings for the arbor yokes. These

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sleeves should be placed as near to the cutter as is practicable so that the arbor yokes may support the arbor close to the cut. Two arbor yokes are furnished with most machines. The smaller sires usually have a yoke with a small bushing to fit the pilot on short arbors in cases where support at the extreme end of the arbor only is permissible. The smaller sires also have a yoke with a larger hole to fit the sleeves mentioned for occasions when the arbor yoke may be placed nearer the spindle end or when both yokes are required. Heavy machines have two yokes with large bushings. Upon some work it is advisable to use both arbor supports, attempting at all times to keep the yokes near the cutters, and whenever possi- ble the arm braces (which tie the overarms and the knee together) should be used. Arbor yoke bushings are adjustable for wear, and a good fit on the arbor sleeves or pilots should be maintained (Fig. 5).

HULUINC METHODS. The most common holding device is the milling machine vise, and it is used extensively for both short- and long-run jobs. Formed he jaws for irregularly shaped work are inexpensive and freqrxntly offer the only means of handling some parts. Before the work held between the vise jaws can be machined accurateIy, the vise must be squared up with the machine spindle. To set a plain vise or a vise without tongues so that its jaws are parade1 to the spindle, place an arbor in the spindle and bring the vise jaws up to the arbor (Fig. 6). The vise can be set at right angles to the spindle by a square placed against the arbor and the laws. Swivel vises may be set by the aid of the graduations on their bases. Work that cannot be ham&d in a vise be- cause of its weight, shape, or other characteristics may be fastened directly to the machine tabie. An assortment of clamps and straps, jacks, a shim, a step block, and a clamping bolt, are shown in Fig. 7. Whenever clamping a piece to the table, the straps should be placed squarely across, in order to have a good bearing at each end, and, if possible, upon a solid section from tabte to strap at the work end. If it is necessary to place a strap on an overhanging part, a support should be placed between the work and the table or the lip will be sprung or broken. Another important consideration is the position of the clamping bolt. It should always be placed as near to the work as conditions will allow, for in this posi- tion it will exert the greatest pressure in the right place and be easier to set up or loosen.

Frxronns. If a suihcient quantity of pieces war- rants the expense, fixtures are usually built to facili- tate handling and to increase production. Since these

Figure 5. Arrangements of d&rent arbor yokes

Figure 6

fixtures a:e made in an endless variety, it is not practical at this time to discuss this phase of milling machine work.

Mounting of Mllllng Cuttera

Milling cutters are mounted on the spindle of a milling machine either directly or by means of arbors

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and adapters. For this purpose, the front end of the spindle or “spindlenose” is provided with (Fig. 8):

I Wrong



1. AIL accurately ground face which is square with the outer surface of the spindle.

2. Four threaded holes and two driving keys for locating and driving adapters and large face mills.

3. An accurately machined tapered hole or socket for locating shank-type arbors,

cutters, and adapters, and to align them with the axis of the spindle.

No. of Taper D d L E B F

30 1% ,692 2% 54 2.7493 ,625s ,685 2.7488 .6252

40 1% 1.005 3% % 3.4993 .6255 ,997 3.4988 .6252

50 2% 1.568 5% 5% 5.0618 1.0006 1.559 5.0613 1.0002

60 4% 2.381 8% 1% 8.7180 1.000 2.371 8.7175 .999

Figure 8

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CLASSIFICATION OF TAPERS AND SIZES. The tapers used for mounting milling cutters are conveniently divided into two general groups or classes known as selj-holding and self-releasing or steep tapers, re- spectively.

Self-holding tapers are characterized by a small inc2uded angle (generally less than about five de- grees) and by the fact that the shank will stay in place without using additional means other than the frictional force between the contacting surfaces when it is firmly seated in the socket.

Self-releasing or steep tnpers are characterized by a large included angle (generally more than about fifteen degrees ) They are dictated by the desirability of achieving uniformity in design; obtaining inter- changeability of various devices such as arbors, collets, and adapters while at the same time pro- viding a taper which will permit easy and quick removal of arbors, cutters, and other tools from the spindle of milling machines.

Types of Mounting for Niing Cutters

Milling cutters may be grouped with respect to the method of mounting as follows: face milling cutters, shank-type cutters, and arbor mounted cutters.

FACE MILLING Cm. Face milling cutters of ‘seven inches in diameter and over are usually mounted directly on the spindlenose and are held in position by four cap screws (Fig. 9).

SHANK-TYPE -as. The shank-type class in- cludes a variety of cutters with an integral shank,

as in end mills, or a sepnrote shimk, as in shell end mills and sometimes in smaller face mills. The shank may be straight or tapered, and it is inserted in the spindlenose either directly or with an adapter, de- pending on the type and the size.

Shank mounted cutters may be classified in two general groups; cutters mounted on a removable shank, and cutlers having an integral shank.

Cutters with Remoonble Shrink. Milling cutters of the shell end mill type are not large enough to permit a counterbore which will fit over the spindle- nose as in face mills. Consequently, they are mounted on the spindle by means of a short arbor known as a shell end mill arbor or “stub arbor” (Fig. 10).

Large-size face milling cutters may also be mounted on the spindle of a milling machine by means of a face mill arbor or adapter. Figure 11 shows this type of face mill mounting used with a quick-chnnge nrlnpter for multiple tooling without flanging the setup of the workpiece.

Standard single-angle milling cutters with threaded boles may be inchtded in the group of cutters having a removable shank. The arbor for these cutters has either a right- or left-hand threaded end. The thread is selected in relation to the “hand” or direction of cutting of the cutter and the hand of rotation of the spindle. There are four combinations of hand of rotation, hand of cutter, and hand of thread (Fig. 12).

Cutters with Integral or Solid Shank. This group includes a wide variety of small milling cutters of standard and special shapes, standard end mills, T-slot, and Woodruff key-seat cutters. These cutters are made solid, with either straight or tapered


Figure 9

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Figure 10

Figure 11




Figure 12

shanks, and are mounted on the standard spindle taper of milling machines by means of adapters and collets.

Adapters and CoUets. The term adapter is used to denote an accessory for mounting various types and sizes of milling cutters on the spindle of a milling machine. A co&t is a two-taper sleeve which is used to reduce the taper of the spindle or an adapter to a smaller-size taper (Fig. 13).

The spring chuck is actually an adapter with a removable spring collet, and is made in different

hole sizes to accommodate straight-shank cutters and drills from 1/8 to 1 inch in diameter. Double end mills can be used with this type of collet (Fig. 14).

ARBOR MOUNTED CUTTERS. Milling cutters of the plain, side, angle, formed, metal slitting saw and other types are made with a standard center hole and keyway for mounting on an arbor held on the spindle of the machine.

Arbor Shank and Flange. Arbors for hole-type milling cutters are made in various lengths and diameters and in two styles which are identified by

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Figure 13

Figure 14

the letters A and B (Fig. 15). The arbor diameter carbon steel, hardened and drawn to a blue. In is ground to close limits throughout its length to fitting a key to the cutter and arbor, both the key insure interchangeability and sliding fit for all and key slots should have dimensions correspond- milling cutters. ing to the standard nominal sizes of arbors and

Use of Keys to Drioe Cutters. The arbor (Fig. 16) cutters. is provided with a fulI-Iength keyway to accommo- Spacing and Bearing Collars. Spacing and bearing date keys for driving the cutters and the bearing collars are used to locate milling cutters on the collars. A good key material is 0.70 to 0.50 per cent arbor and maintain them accurately and rigidly in

Figure 15

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the desired position (Fig. 16). The spacing collars are inserted on the arbor on either side of the cutter, and are used in various lengths to permit the re- quired spacing combinations. Bearing collars are made in one length and have a slightly larger di- ameter than spacing collars. They are used in con- junction with arbor supports (style B, Fig. 16). The collars and the cutters are tightened by means of the arbor nut at the outer end of the arbor.

Use of Style A Arbors. The style A or short arbor is provided with a shank and flange on one end. The opposite end has a pilot and a ,threaded portion for the arbor nut. The pilot is used to support the free end of the arbor. This style of arbor is used chiefly in small-size milling machines.

Use of Style B Arbors. The style B or long arbor, supported by means of one or more arbor supports and bearing collars, is used on both small and large milling machines. Bearing collars fit into the split bushing in the style B support (Fig. 16). The bush- ing is held in the tapered hole of the support by an adjusting nut, thus allowing adjustment of the bushing to the proper fit with the bearing collar. Too loose a fit affects the operation of the machine ~by ca~using inaccuracy and sometimes chatter; too tight a fit generates excessive heat which eventually

may damage both the bearing collar and bushing. A special inner support of the cop type permits

easy arbor removal from the machine without dis- mantling the cutters.

SPECIAL Aa~oas AND ~NPTERS. It is sometimes necessary, particularly in production jobs, to pro- vide special arbors and adapters which permit the execution of milling operations on parts presenting obstructions or which are not accessible when the cutters are mounted on standard accessories. A spe- cial extended c&et adapter for supporting an end mill to circular mill the bolt lugs of a master rod is shown in Fig. 17.

0.n-r~~ Sr~tis. It is not possible to give definite speeds at which milling cutters should be run be- cause varying conditions make corresponding varia- tions necessary in cutter speeds. The size of cutter, type of cutter, rate of feed required, and the rela- tion between the rate of feed and depth of cut all have a bearing on the speed.

The following surface speeds will be found suit- able as a basis from which to work. To achieve the very best results in a particular case, some deviation from the given figures will be, no doubt, advnn- tageous. A plentiful supply of coolant must be used on materials that require it.

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Surface Speeds of Cutters Carbon * High-Speed

Material steel cutters Steel Cutters

Brass . SC-100 FPM 150-200 FPM Cast Iron 40-60 FPM SO-100 FPM Ld~inery Steel 30-40 FPM 80-100 FPM Annealed Tool Steel 20-30 FPM 60-80 FPM

’ Considerably higher speeds can be used with cutters of the new fasl: cutting alloys.

COOLANT. The oil or cutting compound used in milling work is not essentially a lubricant although it is frequently so called, but a cooling agent. In machining some materials, steel for example, con- siderable heat is generated by the cutting action which. unless dissipated, will soon burn the extreme edges of the cutter, causing it to become dull quickly. An abundance of coolant (Fig. 18) is a positive necessity on most steel jobs if the feeds and speeds that are considered right are to be used. Cutting oils are used mainly on high-speed work and where a good finish is desired. Oils vary somewhat in com- position and cutting e5ciency, but in general, they should be fairly clean and have no corrosive action and no objectionable odors.

Fundamentals of the Millinq process

Milling is a process of generating machined sur- faces by progressively removing a predetermined amount of material or stock from the workpiece which is advanced at a relatively slow rate of move- ment or feed to a milling cutter rotating at com- paratively Ligh speed. The characteristic feature of the milling process is that each milling cutter tooth takes its share of the stock in the form of small in- dividual chips. Milling operations are classified as follows:

PERTPHER~L MILLING. The milled surface generated by teeth located on the periphery of the cutter body, as when milling with a helical mill, is generally in a plane pnr&Z to the cotter axis. Milling operations with form-relieved and formed-profile cutters are included in this class. The cross section of the milled surface corresponds to the outline or contour of the milling cutter or combination of cutters used (Figs. 19 and 20).

Figure 18 Figure 19. Combination of peripheral milling cutters for multiple milling operations.

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: i : / ,..~_~~ __..~.-...~~: I Cow / i. -‘m I : ; ; : j cl

21 j it ‘CL_ +- ___.., ----~--, ---. , ; : ,



i 4


Figure 24. Milling locating surfaces on a milling &ture unit at a 36” angle.


Figure 25. Setting workpiece at a known distance from miUing cutter.

CONVENTIONAL OH UP Mr~u~c. In conventional or up milling, the cutter rotates against the direction of feed as the workpiece advances toward it from the side where the teeth are moving upward. The separating forces produced between cutter and work- piece oppose the motion of the work.

CLIMB CUT OR DOWN MILLING. In climb cut or down milling, the cutter rotates in the direction of the feed, and the workpiece thus advances toward the cutter from the side where the teeth are moving downward. As the cotter teeth begin to cut, forces of considerable intensity are produced which favor the motion of the workpiece and tend to’ poll the work under the cutter.

If the workpiece is not held securely on the mov- ing slide, or the slide is not steadily fed by the feeding mechanism, yielding of the work may result in a broken cutter, damaged work and machine, and possible injury to the operator. For this reason, down milling operations are best performed on milling machines which are provided with the necessary equipment to secure positive control of movement of the work, such as the bockhh eliminating deuices used in machines of the screw feed type.

Selectfon of setup

h,CA~NG THE WOBXPIECE WITH &SPECT TO THE CUTTER. To locate the workpiece with respect to the cutter, it is necessary to determine the distance of the workpiece from the axis and face of the milling cutter by using a known reference point on the work- piece. The +/a-in. diameter construction hole indi- cated in Fig. 24 is used for this pmpose. A l-in. diameter aligning bar is inserted in the spindle of the machine or attachment, and a $&in. plug is in- serted in the construction hole.

Lo4xTu.x rmz WORKPIECE WITH RFSPECT To THE CUSTER AXIS. By manually operating the adjustments of the knee, table, and saddle, the %-in. plug is placed in light contact with the aligning bar, held in the spindle of the machine, by gauging the dis- tance between them with a 0.002-in. feeler gauge. This thickness must be added wber. calculating the distance between the axis of the spindle and that of the plug in the workpiece. When contact is finally established, the distance between the axes of the cutter and the plug is 0.752 in. (Fig. 25). This dis- tance is equal to the sum of the aligning bar radius, the plug radius, and the O.OO%in. thickness of the feeler gauge. The micrometer dial in the cross ad- justment is set to zero reading, and the machine table

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is lowered so that the workpiece clears the aligning bar. The bar is then replaced with the 3-m. diameter shell end mill selected for this job.

LcxxTlNC THE WoRIcplEcE WITH RESPECT TO THE FACE OF THE Curraa. The table of the machine is adjusted vertically so that the reference plug in the workpiece is near the face of the cutter. The cross adjustment is not moved, and the cutter &.s will remain at 0.752 in. from the center of the plug (Fig. 26). The distance, d, between the face of the cutter and the surface of the plug is measured by means of a vernier height gauge (Fig. 28). The difference (d - y4) in. will be the distance between the face of the cutter and the center of the plug. The mi- crometer dial on the vertical hand adjustment is now set to zero reading. To place the cutter in the plane of surfaces A and C it is necessary to move the knee a distance which is obtained by subtracting the distance (d - Y’ in.) from the limits 2.127 in. maximum - 2.123 in. minimum (Fig. 24). If the distance d is 0.500 in., tbe following results are obtained:

2.l.27 - (0.500 - 0.250) = 1.877 in. 2.123 - (0.500 - 0.250) = 1.873 in.

Hence the knee will be lowered 1.875 in., which is the noerage of the two limits.

To mill surface A, the table in this case is moved out so that the periphery of the cutter lines up with the shoulder at 1.002 in. to 0.998 in. from the center of the plug (Fig. 24 ) . The amount of the adjustment is calculated as follows:

1.002 + 0.75% + 3/2 = 3.254 in. 0.998 i- 0.752 + 3/2 = 3.250 in.

where 0.752 in. is the center distance between the axis of the plug and the cutter, and yz is the cutter radius. If the cutter runs out, as determined by in- dicator check, one-ha% of the total run-out should be added to the above figures.

After lowering the knee 1.875 in., the table is moved out 3.252 in., which is the average of the calculated limits. These adjustments will place the workpiece in position for milling surface A.

SELECTION OF Currr~c Spano AND FEED. The cutting speed for the high-speed steel shell end mill is selected from Table 33 in the Appendix. The cut- ting speed for medium cast iron of B30-220 Brinell hardness is 95 ft per min. Because of the depth of the stock to be removed, the cutting speed is conserva- tively reduced to about 75 ft per mm to avoid prema- ture dulling of the cutter. At this speed, the cutter

Figure 26. Setting the face of the cutter at a known distance from the locating plug.

rpm is approximately 92, which is the rpm available in the machine. The feed rate, based on a feed per tooth of 0.095 in. (Table 28 in Appendix) is 0.905 X 10 X 92 = 4.60 in. per min. The actual feed wih be 4% in. because this is the nearest feed available in the machine. The rate of stock removal is there- fore 2ah x */a x 45/s = 1.60 cu in. per min, and the power at the cutter for a value of a = 1 (Table 30 in Appendix, hne 2, face milis) is 1.60 horsepower, well within the power capacity of the milling ma- chine. The above calculations can also be made by means of Table 34 in the Appendix.

Mnxuc fhRFAcFs B AND C. When surface A has been milled, the workpiece is cleared from the cutter and repositioned for milling surface .B by reading 1.999 + 3.338 + 3.999 = 7.338 in. on the dial of the table screw. This is equal to the dimension on the workpiece plus the diameter of the cutter. Surface C is milled by lowering the knee 2.438 - 2.125 = 0.313 in. from the previous position as indicated by the dimensions on the workpiece.

Milhg thfaces ot Compound Angles on SibPoint Tools

Examples of surfaces inclined at compound angles are commonly found in single-point cutting tools, milling cutter teeth, and dovetails. ‘rhe following cases have been selected for the purpose of illus- trating the variety of settings which may he encoun- tered in practice together with the procedure to follow in machining:

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Fiylrre 87. hiilling tool point to given angles and dimensions.

Figure 28. General views of setup used for milling cuuing angles of hzming tool shown in Figure 27.

MILL~NC THE CW~TINC ANGLES OF A fiIGHT-HAND CUT, STRAIGHT, SINGLE-POINT Toot. (See Fig. 27.) The single-point tool is used for turning a square shoulder. Tool meterial: 18-4-l high-speed steel, an- nealed 200 BHN.

Selection of Setup. The tool blank has been ma- chined on the four sides previous to milling the surfaces on the cutting end of the tool. It is then clamped in a toolmaker universal vise located on the table of a horizontal milling machine. The vise jaws are set in a horizontal plane and parallel to the axis of the machine spindle (Fig. 28). In order to place the work at the proper working distance from the cutter, the vise is aligned with the center T-slot of the table and is bolted near the center por- tion of the table travel to avoid unnecessary table overhang.

A llh in.-diameter standard high-speed steel end mill (8 teeth, right-hand cut, right-hand helix, ‘A s-in. corner radius) is mounted on the spindle of the machine by means of a quick-change adapter.

A cutting speed of approximately 80 ft per min is indicated in Table 33 in the Appendix for the 200 Brine11 hardness number of the material to be milled. But this figure is conservatively reduced to about 70 ft per min. The revolutions per minute corresponding to this cutting speed can be deter- mined from Table 34 in the Appendix. Here it is found that for a cutting speed of 70 ft per min and a cutter diameter of 1% in., the rpm is approxi- mately 175. However, the nearest available rpm in the machine used for this job is 187. Hence, the actual cutting speed will be approximately 75 ft per min.

The feed rate is calculated from the number of cutter teeth, the rpm of the cutter, and the feed per tooth. With a feed per tooth of 0.003 in. for the alloy steel to be milled (see Table 28 in the Ap- pendix) and using an 8-tooth cutter, the feed rate is approximately 3’i/s in. The actual feed of 4% in. is selected, however, because it is the nearest feed available in the machine.

First Operation-Milling the Tool Face at a 7-De- gree Side Rake Angle. (See Fig. 27.) The tool blank is clamped in the vise with sufficient shank length projecting beyond the jaws toward the cutter (Fig. 28) to allow the cutter to take the width of cut cor- responding to the dimension of the tool point. The width of cut should be slightly larger than the final dimension shown in the drawing, thus allowing a small amount of stock for finishing the front end of the tool. In this case, the tool blank is set with respect

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Figure 29. Setup for milling the 7” side rake angle.

to the cutter by means of the cross adjustment so that the width of cut taken by the cutter is 1%6 in.

With a bevel protractor set at a 7-degree angle and resting on the shank at right angles to the vise jaws, the body of the vise is tilted in the direction shown at A, Fig. 29 until the air bubble in the level is centered. The angle can also he read on the gradu- ated scale located on one side of the vise body. The vise body is then clamped to the dBASE, and, after raising the machine knee so that the cutter will cut 1/3* in. below the rough edge of the blank (Fig. 29), the table feed is engaged in a right-to-left direction, allowing the cutter to take an up milling cut. A close-up view of the equipment used in this opera- tion is shown in Fig. 30.

Second Operation-Miliing the Tool Flank at a 7-Degree Side Relief Angle. (See Fig. 27.) The set- ond operation is the same as the first operation, but the surface to be milled (tooE flank) is now located in a vertical plane at right angles to the face of the tool. The setup is changed as follows: (See Fig. 31.) The vise is indexed 180 degrees on its base, and the tool blank is relocated so as to place the flank of the tool on top. The table is now fed from right to left after raising the knee to take a l/&-in. depth of cut below the rough edge of the blank.

Third Operation-A4ilhg the Tool End at on &De- gree End Cutting Edge Angle and 7-Degree End Relief Angle. (See Fig. 27.) The S-degree end cutting edge angle and the ‘I-degree end relief

Figure 90. Equipment used in milling 7” side rake angle on tool shown in Figure 27.

,. W , y.+..--- j- ..-.. 1.; TABLE r.F-J -___-.. iw.-.--l.

-1. _-._ --..- -._--..- 4 .-..---- 1 1-

Figure 31. Setup for milling the 7” side relief angle

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angle, measured in two planes at right angles to each other, determine the location of the end surface DEFG of the tool point with respect to the tool shank (Fig. 32). In order to mill this surface so that the angles determining it have the given values, the tool blank must be placed with respect to the cutter so that the sulfate DEFG is parallel with the face of the cutter.

For this purpose, two lines DE and DG are scribed on the tool shank, making angles of 7 and 8 degrees with the end of the tool on the sides corresponding to the end relief and end cutting edge angles, re- spectively. The vise jaws are placed horizontally and parallel to the spindle axis. The tool blank is placed in the vise with the base of the tool up and with the cutting end of the tool toward the milling cutter. The tool shank is clamped lightly so that, when a bevel protractor, preset to the 7-degree end relief angle, is placed lengthwise on the tool shank, the

,’ tool blank can be tilted in a vertical plane in the ,‘, vise until the air bubble in the level is centered.

The line DE will now be in a vertical plane and ‘,: paral!el to the face of the cutter (A, Fig. 32).

The same result could be obtained by placing a :I’ straightedge against the face of the cutter and

subsequently tilting the tool shank until the line DE :i, lined up with the straightedge. The tool shank is ‘:: then clamped tightly between the vise jaws.

In order to set the tool for the S-degree end cutting ~,,~ edge angle without disturbing the previous setting,

the vise body is now swiveled in a horizontal plane, parallel to MM (A, Fig. 32), until the line DG is parallel to the face of the cutter. A straightedge held against the face of the cutter can also be used for this setting. This method of setup is generally satis- factory because, in practice, it is not necessary to hold the angles of cutting tools to close tolerances. In some cases, however, it may be required to mill surfaces at compound angles to greater accuracy than this method would provide. In this instance, it is advisable to know the angle C (B, Fig. 32), at which the tool blank or the vise must be swiveled in a horizontal plane such as MM, after tilting it in the vertical plane to the ‘I-degree end relief angle. This angle is not the .same as the S-degree end cutting edge angle because it is located in a different plane. The tool angles are always given in the ortho- graphic projection of the various views of the cutting end of the tool.

The angle C can be calculated by means of the following general formula which is derived from the geometry of Fig. 32:


tanC=tanbcosa (1)

C = compound angle, degrees a = given angle, degrees (first angle used in the

setup ) b = given angle, degrees (second angle used in

the setup).

Substituting the known values of angles a and b in formula 1 (which in the present case are 7 and 8 degrees, respectively ) :

tanC=tanScos7 = 0.141 x 0.993 = 0.140


In this example, the angle C differs but slightly from the given S-degree end cutting edge angle so that no appreciable error is made by swiveling the vise to this angle rather than the ‘i-degree 58- minute angle C.

Figure 32. Determining the compound angle for milling the end of cutting tool shown in Figure 27.

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In other cases, however, the compound angle mey deviate appreciably from the value of the given angle, and the accuracy of machining will be affected if the setup is made by using the given angles instead of the compound angle.

As a general rule, ~clwn the gicert trrtglcs we small these angles can be used in making the setup, the compound angle being very nearly the same as one of the angles. When the gicea nngles ore large, the compound angle differs appreciably from either of the given angles.

For example, if o = 79 degrees and b = 30 degrees:


tan c = tan 30 cos 29 = 0.577 x 0.875 = 0.505

C = 26” 48

In this instance, it would be desirable to use the \:niae of the compound angle in making the setup.

To avoid mistakes which may prove costly, it is preferable to calcufate the value of the compound angle in all cases, using the result as a guide in making the setup.

Figure 33. Equipment use:i in milling the end surface of cutting tool hwn in Figure 32.

Figure 34

In setting up for machining the end of the cutting tool shown in Fig. 32, the order in which the two angles have been used might be reversed. The tool blank can be set first in the vertical plane at the S-degree end cutting edge angle, and afterwards swiveled in the horizontal plane at the 7-degree end relief angle. In Formula 1, for determining the com- pound angle, the functions of the two angles would then be interchanged. The milling operation is com- pleted at one setting of the tool blank by removing the required amount of stock with the end of the cutter (Fig. 33).

MILLING THE FACE OF .% LE.FT-HAND CUT, SINGLE- POINT TOOL HAVING RACK AND SIDE HAKE ANGLES. (Fig. 34.) Other conditions are the same as for the tool shown in Fig. 27.

Selection of Setup. The setup for machining the faces of tools having back and side rake angles (Fig. 34) is similar to that used in milling the end of a tool as outlined in the third operation for milling the cutting angles of a right-hand cut, straight, single- point tool.

Lines are scribed on the tool blank to indicate the location of the angles. After aligning the vise jaws with the spindle axis, the tool shank is clamped so that the back of the blank is on top. The vise is then tilted at 7 degrees, corresponding to the side rake angle.

To obtain the 15-degree back rake angle, the vise body is swiveled on its base until the scribed line is parallel to the face of the cutter.

The compound angle C is then calculated by sub- stituting the values of the side rake angle (first angle used) and back rake angle (second angle) as in formula 1:

tan c = tan 15 cos 7 = 0.268 x 0.993 = 0.266


c = 14” 54’

Therefore, use of the 15-degree back rake angle will provide sufficient accuracy in this setup becnusc the compound angle is nearly the same as the value of the back rake angle. The milling operation is now performed with the periphery of the cutter, using the same feed and speed as dcscribcd for milling the cutting angles of a right-hand cut, straight, single- point tool. The setup is shown in Fig. :33. The other angles we milled under the same proccdurc as dc- scribed previously.

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Figure 35. Use of motor-driven universal-milling overarm attachment in milling surfaces at compound angles on a single-point cutting tool.

Setup with Motor-Driven Uniuersal-Milling Over- arm Attachment. When the milling machine is equipped with a motor-driven universal-milling over- arm attachment (Fig. 35), which is provided with two independent angular adjustments at right angles to each other, the setup can be made by utilizing the angular adjustment of the cutter in conjunction with the angular adjustment of the vise (Fig. 36).

The milling operation is performed with the face of the cutter and using the feed rate previously out- lined. However, the cutting speed is changed to ap- proximately 70 ft per min. which corresponds to the 180 rpm available in the motor-driven overarm attachment rather than the 187 ‘pm of the machine spindle.

The combination of the motor-driven universal- milling overarm attachment and toolmaker universal vise provides a very convenient combination for quick and accurate milling of the cutting angles of single-point tools an< face recesses for tips of sin- tered carbide or other materials (Fig. 37). The vari- ous operations, including recesses for carbide tips, can be completed without relocating the tool blank in the vise. The procedure is as follows:

MILLING THE FACE AND CARBIDE TIP Hwzss IN A SINGLE-POINT TOOL. The dimensions of the recess and the values of the tool angles when milling the face and carbide tip recess of a single-point cutting tool having negative side and back rake angles are

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shown GI Fig. 38; The tool blank is made of SAE 1040 steel of 170-180 BHN.

First Operation-Milling Tool Flank. In the first operation, the flank of the tool is milled at a 1% degree side cutting edge angle and a IO-degree side relief angle using the periphery of the cutter. The general setup is shown in Fig. 37. The tool blank is clamped in the toolmaker universal vise, and the vise jaws are set in a horizontal plane parallel to the cutter axis.

The vise body is now swiveled on the base to a 15degree angle. The spindle of the motor-driven universal-milling overarm attachment is swiveled counter-clockwise on the compound bracket, parallel to the face of the column, until the cutter axis is parallel to the scribed line on the tool blank. This line marks the position corresponding to the lo- degree side relief angle (or to the value of the angle C, the compound angle of the lo-degree side relief angle, nbtained from formula 1 after substituting the known vahes ) :

tan C = tan 10 cos 15 = 0.176 x 0.966 = 1.700

Figure 37. Milling the flank of a sin&-point twl to 10” side relief and 15” side cutting edge angles, by using a motor-driven universal-milling overarm attachment and a toolmaker universal vise.


C=9”39’ -TGh, 1

SeZection of Milling Cutter, Cutting Speed, and Feed. The milling cutter for this operation is a I?&i!-in. diameter, standard, high-speed steel end mill (S teeth, right-hand helix), mounted for use with a quick-change adapter. The cutting speed is about 70 ft per min, the same as used in the previous operation.

The feed rate is calculated from the assumed value of the feed per tooth, which is taken equal to 0.003 in. for the 180 BHN alloy steel being milled (see Table 28 in Appendix). IIence, for the given number of teeth and actual rpm (see Table 34 in Appendix), it is found that the approrimate feed rate is 4.49 in. per min. The actual feed rate is 4ys in. per mio

Figure 3M. Dimensions of a single-point, right-hand cut

because this is the nearest feed rate available in the carbide tipped turning tool.

machine. The work is fed to the cutter by using the other small-size milling cutters, the strength of the cross feed. cutter is a factor in determining the rate of stock

To avoid the possibility of the cutter striking the removal. Cutter breakage may occur if the selected vise, a stop dog should be placed in the cross feed rate of stock removal is too high for the size of the controls to automatically stop the feed as the cutter cutter. completes the cut. The proper rate of stock removal can be obtained

RATE OF S=rocK REMOVAL IN RELATION TO STRENCTH by determining the allowable horsepower at the OF TKE CUXXXR. In operations with end mills and cutter in relation to the cutter size. In end mills

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this can be calculated by means of the following formula:


where: H, = horsepower allowable at the cutter. D = neck diameter Of cutter in inches (Fig.

39). S = allowable stress, psi. Depending on oper-

ating conditions, this value varies between lO,OOO and 20,000 psi for high-speed steel cutters. For end mills tipped with carbides, the allowable stress is that Of the material of the shank.

C = cutting speed in feet per minute. L = distance between neck section and point

of load application (Fig. 39) in inches.

t 1000 -- 300 350

--0 ;: AM) ..A ..Y)

-- 600 .Scm .I ,550



__ ,600

400 100 250


-- -- /900 .,oo/’ .d


=7/I: ;;iF /’ -- I.404 ,/’

i :

I:% 100 l.800 80 *.ooo

Figure 39. End mill dimmsions for calculating allowable horsepower.

Figure 40. Alignment chart for calculating aUowabIe horsepower for end milk.

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When the values of the variables shown in formula 2 are known, the calculation of H, can also be made by means of the alignment chart shown in Fig. 40.

Knowing the allowable horsepower at the cutter, the rate of stock removai V can be calculated from Table 34 in the Appendix, or from the empirical formula 3 which follows, after selecting the value of the factor a from Table 30 in the Appendix.


H, = a V” (3)

H, = horsepower at the cutter. V = rate of stock removal in cubic inches per

mmute. a = horsepower at the cutter u&n the rate of

stock revumal is one cubic inch per minute. n = slope of the curve, or exponent for the

rate of stock removal V.

The application of formula 2 is illustrated by checking the value of the feed rate used in this operation. Standard end mills of 11/z in.-diameter have a neck diameter D of approximately 1 in. The length L is 1 in., the work having been as close as possible to the cutter shank.

The value of the allowable stress S for high-speed steel cutters is assumed equal in this case to 15,000 psi. The cutting speed C is 70 ft. per min. Substitut- ing these values in formula 2:

H = 15,000 x 70 p 336,000x1

105 =m = 3.13

This is the allowable horsepower H, the cutter. From formula 3, it is found that for an average value of a of 1.25 (Table 30 in the Appendix) the rate of stock removal is:

3.13 = 1.25 V3”

” = 3.134/s 1.25

but: = 3.40 cu. in. per min.


In the present case, the feed rate is 45/s in. per min., the width of the cut is 1 in., and the maximum depth of the cut approximately 0.267 in. Hmce:

V = 4ys x 0.267 x 1 = 1.24 cu. in. per min.

This value is well within the maximum allowable value of 3.40 cu. in. per min. obtained in the c&ula- tion for the cutter in question. Thus the feed rate of 4j/s in. per min. is satisfactory and not excessive.

Second Operation-Milling Tool End. In the sec- ond operation, the front end of the tool blank is milled to a lo-degree end cutting edge angle and a lo-degree end relief angle.

The vise setting in the horizontal plane is now changed from the 15-degree angle of the previous operation to the IO-degree end cutting edge angle. The table is moved longitudinally to the left to locate the work so that the cutter will cut as in up milling.

To obtain the lo-degree end relief angle, the spindlehead of the attachment is tilted counter-clock- wise in the plane at right angles to the machine column. The angle to which the spindlehead is tilted is the compound angle C, obtained as previously de- scribed by scribed lines or by means of formula 1:

and :

tan C = tan 10 cos 10 = 0.176 x 0.9S4 = 0.173

c = 9049

The cut is taken with the teeth on the periphery of the cutter by feeding the table from left to right. The setup used in this operatioo is shown in Fig. 41.

Figure 41. Setup for milling end of sir&-point tool shown in Figure 311.

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Third Operation-Milling Tool Face. When mill- ing the face of the tool to the S-degree negative side rake angle, the B-degree negative back rake angle, and the recess for the carbide tip is as shown in Fig. 38.

Setup for Milling the Tool Face. The tool blank is clamped in the vise, and the vise is then tilted in the plane parallel to the face of the column to the 3-degree negative side rake angle. The spindle- head is set at the compound angle of the B-degree negative back rake angle by tilting it away from the column 6 degrees (Fig. 42); this is approximately the value of the compound angle obtained from formula 1. The cut is taken with the face of the lr/$in. diameter end mill, used in the previous operations, by feeding the table of the machine from left to right.

Setup for Milling the Recess for the Carbide Tip. To mill the recess for the carbide tip (Fig. 38), the lr&n. diameter cutter is now replaced with a 4/a-m. diameter standard high-speed steel end mill (4 teeth, right-hand cut, right-hand helix) which will produce the r/i-in. radius on the inner corner of the recess.

At the cutting speed of 95 ft. per min. used to re- duce the cutting load on the rather small cutter, this will operate at 726 rpm (see Table 34 in the Appendix). The available rpm in the motor-driven universal-milling overarm attachment is 740. Conse- quently, the actual cutting speed will be 96.8 ft. per min. With a feed per tooth of 0.002 in., the feed rate would be approximately 5.920 in. The actual feed rate, however, is 5% in., this being the nearest feed rate available in the machine.

Checking the Rate of Stock Removal in ReZution to the Strength of the Cutter. At the feed rate estab- lished, and with depth and width of cuts of 3/1s in. and a/’ in., respectively, the rate of stock removal is:


= 0.404 cu. in. per min.

and the corresponding horsepower at the cutter (formula 3) for the average value of a of 1.25 (Table 30 in Appendix is:


= 1.25 (0.404)%

= 0.633

But from formula 2, the allowable horsepower H, where D = r/a in., S = 10,009 psi, C = 95 ft. per min., and L = sh in., becomes:

95 x 4 -33.6~3~8 = 0.470

Since the horsepower corresponding to the selected operating conditions is higher than the allowable horsepower, a modi6cation of the assumed values of the depth, width, and feed rate becomes necessary in order to avoid the possibility of cutter breakage.

By maintaining the same values for the feed rate and width of cut, but reducing the depth of cut to 3/3a in., the rate of stock removal becomes 0.202 cu. in. per min, and the horsepower at the cutter is reduced to 0.377. This value is now lower than the allowable horsepower, and the cut can be taken safely at the selected feed rate.

Figure 42. Setup for milling face of tool shown in Figure 33 at angles of 3” side rake and 6” back rake.

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However, two passes will now be required to com- plete the operation, or one pass can be taken at the full depth of cut but with half the feed rate. If the cut is taken in two passes, the width of cut in the first pass should be 0.010 in. less than the specified value of $6 in. to avoid leaving a ridge on the sides of the recess.

Procedure for Locntirg the Tool Blank in Position for Milling the Recess. The sides of the recess are at right angies to each other, and the side S, Fig. 38, is at right angles to the side cutting edge. Hence the tool blank must be set with the side cutting edge at right angles to the direction of feed. This is done by swiveling ihe vise oo its base to the 15-degree side cutting edge angle. The bottom surface of the recess should be parallel with the face of the tool. Since the tool face was set parallel with the face of the cutter in the previous operation, this condi- tioo will not be altered when the vise is swiveled to the 15-degree angle required for the present operation. Therefore it will not be necessary to make any other change in the setup. The workpiece is aligned with the cutter, with sufficient accuracy for

Figure 43. Setup for n&ing the carbide tip recess on a single-point tool.

this job, by utilizing scribed lines which give the outline of the recess on the surface of the tool.

If the operation is completed in two passes, the position of the saddle at the beginning of the cut is marked on the top of the knee, which has been spotted with red lead, by drawing a pencil line along the edge of the saddle. This mark will be used for relocating the starting position for the second pass. The work is set for the 3/32-in. depth of cut. As the cutter rotates at the selected cutting speed, the table (and consequently the work) is fed to the cutter by hand to the proper width of cut. The cross power feed is then engaged to feed the work away from the column. The second pass is taken in the same manner after the table is moved to the right, and after the saddle is correctly positioned with the help of the pencil mark on top of the knee. A view of the setup used when milling the recess is shown in Fig. 43.

cutting spirals

The spirals most commonly cut on milling ma- chines are spiral gears, spiral mills, counterbores, and twist drills.

The method of producing the spiral movement of the work has been previously described, and the manner in which the head is geared is shown in Figs. 44 and 45. The four change gears are known as gear on screw, first gear on stud (because it is the first to be put on), second gear on stud, and gear on worm. The screw gear and first gear on stud are the drivers, and the others are the driven gears. By using different combinations of the change gears furnished, the ratio of the longitudinal movement of the table to the rotary movement of the work can be varied; in other words, the leads of the spirals it is possible to cut are governed directly by these gears. Usually they are of such ratio that the work is advanced more than an inch while making one turn; thus the spirals cut on milling machines are designated in terms of inches to one turn, rather than turns, or threads, per inch. For example, a spiral is said to be of 8 inches lead, not that its pitch is +&turn per inch.

The feed screw of the table has four threads to the inch, and 40 turns of the worm make one turn of the headstock spindle; accordingly. if change gears of equal diameter are used, the work will make a complete torn while it is moved lengthwise 10 inches; that is, the spiral will have a lead of 10 inches. This

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Figure 44. Gearing when no idler is required.


Figure 45. Gearing with idler in use.

is the lead of the machine, and it is the resultant of the action of the parts of the machine that are always employed in this work, and it is so regarded in making the calculations used in cutting spirals.

PRINCIPLE SAME AS FOR CHANCE GEMS OF A LATHE. In principle, these cahxlations are the same as for change gears of a screw cutting lathe. The compound ratio of the driven to the driving gears equals, in all cases, the ratio of the lead of the required spiral to the lead of the machine. This can be demonstrated readily by changing the diameters of the gears. Gears of the same diameter produce, as explained, a spiral with a lead of 10 inches, the same lead as the lead of the machine. Three gears of equal diameter and a driven gear double this diameter, producing a spiral with a lead of XI inches, or twice the lead of the machine. With both driven gears, twice the diameters of the drivers, the ratio being compound, a spiral is produced with a lead of 40 inches, or four times the machine’s lead. Conversely, driving gears twice the diameter of the driven produce a spiral with a lead equal to I/ the lead of the machine, or 21/ inches.

Driven gears = Lead of required spiral Driving gears Lead of machine

or, since the product of each class of gears deter- mines the ratio, the head being compound geared, and since the lead of the machine is 10 inches,

tie Product of driven gears =Lead of required spiral. Product of driving gears 10

That is, the compound ratio of the driven to the driving gears may always be represented by a frac- tion whose numerator is the lead to be cut and whose denominator is 10. In other words, the ratio is as the required lead is to 10. For example, if the required lead is 20, the ratio is 20 : 10. To express this in units instead of tens, the ratio is always the same as one-tenth of what the required lead is to 1. And frequently this is a very convenient way to think of the ratio; for example, if the lead is 40, the ratio of the gears is 4 : 1. If the lead is 25, the gears are 2.5 : 1, and so on.

To illustrate the usual calculations, assume that a spiral of l&inch iead is to be cut. The compound ratio of the driven to the driving gears equals the desired lead divided by 10, or it may be represented by the fraction ‘2/1a. Resolving this into two factors to represent the two pairs of change gears, ‘%a = 3/2 x ys. Both terms of the 6rs.t factor are multiplied by such a number (24 in this instance) that the resulting numerator and denominator will correspond with the number of teeth of two of the change gears furnished with the machine (such multiplications do not affect the value of a fraction) 3/1 X 24/24 = rss. The second factor is similarly treated, $&, x 8/8 = s2/4a, and the gears with 72, 32, 43 and 40 teeth are selected.

The first two are the driven, and the last two the drivers, the numerators of the fractions representing the driven gears. The 72 is the worm gear, 40 the 2rst on stud, 32 the second on stud, and 48 the screw gear. The two driving gears might be transposed, and the two driven gears might also be transposed, without changing the spiral. That is, the 72 could be used as the second on stud and the 32 as the worm gear if such an arrangement were more con- venient. The following rules express in abridged form the methods of figuring change gears to cut given spirals and also of ascertaining what spirals can be cut with change gears.

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~~. ,,,, ,,,: ,,,, ~, ,,‘, ,‘, ,~,, ,., ,, ~, ,~,,


RULES FOR OBTAINING ~tp: RATIO OF THE GEARS NECLWARY TO CUT A GIVEN SPIRAL. Note the ratio of the required lead to 10. This ratio is the com- pound ratio of the driven to the driving gears. Ex- ample: If the lead of the required spiral is 12 inches, 12 to 10 will be the ratio of the gears. Or, divide the required lead by 10 and note the ratio between the quotient and 1. This ratio is usually the most simple form of the compound ratio of the driven to the driving gears. Example: If the required lead is 40 inches, the quotient is 40 c 10, and the ratio 4to 1.

RULE FOR DETERMINING NUMBER OF TEETH OF GEARS REQUIRED TO CUT A GIVEN .%‘IBAL. I~iaving obtained the ratio between the required lead and 10 by one of the preceding rules, express the ratio in the form of a fraction; resolve this fraction into two factors; and raise these factors to higher terms that correspond with the teeth of gears that can be conveniently used. The numerators will represent the driven and the denominators the driving gears that will produce the required spiral. FOI sample: What gears shall be used to cut a lead of 27 inches?

48 x 72 2x0 z 74 x y5 = (3/2 x “y&J) x (“it x %) =mo

From the fact that the product of the driven gears divided by the product of the drivers equals the lead divided by 10, or one-tenth of the lead, it is evident that ten times the product of the driven gears divided by the product of the drivers will equal the lead of the spiral. Hence the rule:

RULE FOR ASCERTAIN~NC WHAT SPIRAL MAY BE CUT BY ANY GIVEN CHANCE GEARS. Divide ten times the product of the driven gears by the product of the drivers, and the quotient will be the lead of the re- sulting spiral in inches to one turn; For example: What spiral will be cut by gears with 48, 72, 32, and 40 teeth, the first two being used as driven gears? Spiral to be cut equals

10 x 48 x 72 32 x 40 = 27 inches in one turn.

This rule is often of service in determining what spirals may be cut with the gears the machinist chances to have at hand. Combinations of gears that are too small in diameter to reach for right-hand spirals can generally be used for left-hand spirals because the reverse gear is then required sod will enable the gears to reach.

As mentioned, the two driving gears or the two driven gears of any combination can be transposed, but a driver must not be substituted for a driven or vice versa. Four different arrangements of the

gears of any combination are thus possible without changing the ratio, and when one arrangement inter- feres or will not reach, the others should be tried. Thus, the gears to give a lead of 3.60 in. are: drivers, 100 teeth and 32 teeth; driven, 24 teeth and 48 teeth. By transposing the gears, the following four arrangements may be obtained:

Gear on screw 1st gear on stud

DNVERS 1st 2nd 3rd 4th 100 32 100 32 32 100 32 100 DIUVEN

2nd gear on stud 24 24 43 43 Gear on worm 43 48 24 24

The first arrangement, however, is found by actual test to be the only one available owing to the fact that the interference of the gears in the other com- binations prevents their meshing properly.

When very short leads are required, it is preferable to disengage the wormwheel and connect the gear- ing directly to the headstock spindle (using the differential indexing center). This method gives leads one-fortieth of the leads given in the table for the same combinations of gears. Thus, for a lead of 6.160 in., the table calls for gear on worm, 56 teeth; 1st gear on stud, 40 teeth; 2nd gear on stud, 44 teeth; and gear on screw, 100 teeth. Putting the %-tooth gear on the spindle instead of on the worm gives the following lead:

6.160= .I,54 in. 40

By this method, very short leads may be obtained without excessively straining the mechanism, but the regular means of indexing the work cannot be employed. A method that can be used for indexing when using the differential center is to have the number of teeth in the gear on the spindle some multipie of the number required to be indexed. Swing the gears out of mesh and advance the gear on spindle the number of teeth required to index the work one division at each indexing. Thus, if 9 divisions are required with a lead of ,261 in., select a lead from the table equal to about ,261 in. X 40 = 10.440 in. when the gear on worm (which will not be the gear on spindle) is some multiple of 9, as 72. The nearest lead is 10.467 in., which gives

10.467= .2617 in. lead 40

giving an error of .0007 inch. To index the work, the gear on spindle is advanced 7% = 8 teeth at each indexing.

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There are also short lead attachments which can be used to cut short leads. An index plate is pro- vided for use in cutting multiple threads.

POSlmON or THE TABLE IN Cum~c SPIRALS. The change gears having been selected, the next step in cutting spirals is to determine the position at which the table must be placed to bring the spiral in line with the cutter as the work is being milled. The correct position of the table is indicated by the angle shown at A, Fig. 46; note that this angle has the same number of degrees as angle B, which is termed the angle of the spiral and is formed by the iater- section of the spiral and a line parallel with the axis of the piece being milied. ‘The reason that angles A and B are alike is that their corresponding sides are perpendicular to each other.

The angle of the spiral depends upon the lead of the spiral and the diameter of the piece to be milled. The greater the lead of a spiral of any given diameter, the smaller the angle, and the greater the diameter of any spiral with a given lead, the greater the spiral angle. The angle desired can be ascertained in two ways, graphically or, more conveniently, by a simple calculation and reference to a table of natural tan- gents. ;:n determining it graphically, a right triangle is drawn to scale. One of the sides which forms the right angle represents the circumference of the piece in inches, and the hypotenuse represents the line of the spiral. The angle between the lines representing the path of the spiral and the lead of the spiral is the angle of the spiral. This angle can be transferred from the drawing to the work by a bevel protractor, or even by cutting a paper template and winding it about the work as shown in Fig. 47. The machine is then set so that the spiral or groove as it touches the cutter will be in line with the cutter. The angle may also be measured and the saddle set to a corre- sponding number of degrees by the graduations on the base.

The natural tangent of the angle of the spirai is the quotient of the circumference of,the piece divided by the lead of the spiral. The second method of obtaining the angle of the spiral is to divide the circumference of the piece by the lead and note the number of degrees opposite the Ggures that corre- spond with the quotients in a table of natural tan- gents. The angle having been thus obtained, the saddle is set by the graduations on the base. This second method is more satisfactory because it is more accurate and there is less liability of error than with the first. The saddle can be set to the proper angle, but before cutting into the blaak, it is well to let the mill just touch the work, then run the work along

Figure 46

Figure 47 Figure 48

Figure 49 ’ ’

by hand and make a slight spiral mark, and by this mark see whether the change gears give the right lead. Special care should be taken in cutting spirals that the work does not slip. When a cut is made, it is well to drop the work away from the mill while coming back for another cut or the mill may be stopped and turned to such a position that the teeth will not touch the work while the table is brought back preparatory to another cut.

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SE~TINC CUTER CENTRAL. In making such cuts that are alike on both sides (for instance. the threads of worms or the teeth of spiral gears), care must be taken to set the wsxk centra!!y perpendicular with the center iine of the cutter before swinging the sadd!e to the angle of the spiral.

Cots that have one face radial, especially those that are spiral, are best made with an angular cutter of the form shown in Fig. 48 because cutters of this form readily clear the radial face of the cut, keep sharp for scune time, and produce a smooth surface.

TWIST DRILLS. The operation of milling a twist drill is shown in Fig. 49. The drill is held in a co&t or chuck, and, if very long, it is allowed to pass through the spindle of the headstock. The cutter is brought directly over the center of the drill, and the table is set at the angle of spiral. The depth of groove in a twist drill diminishes as it approaches the shank in order to obtain increased strength at the place where the drill generally breaks. The varia- tion in depth is conditional, depending mainly on the strength it is desirable to obtain or the usage to which the drill is subject. To secure this variation in the depth of the groove, the spiral head spindle is elevated slightly, depending on the length of the flute and diameter of the drill. The outer end of the drill is supported by the center rest, and when quite small, should be pressed down firmly, until the cutter has passed over the end. The elevating screw of this rest is hollow and contains a small center piece with a V-groove cut therein to aid in holding the wtirk central. This piece may be made in other shapes to adapt it to special work.

Another and very important operation on the twist drill is that of “backing off the rear of the !ip t3 give it the necessary clearance to prevent excessive friction during drilling. Figure 50 shows the saddle is turned about one-half degree as for cutting a right- hand spiral, but since the angle depends on several conditions, it will be necessary to determine what the effect will be under different circ*mstances. A slight study of the figure will be sufficient for this if the effects of the different angles, miIIs, and pitches of spirals are assumed. The object of placing the saddle at an angle is to cause the mill E to cut into the lip at e’, and have it just touch the surface at a’. The line r being parallel with the face of the mill, the angular deviation of the saddle is shown at a in comparison with the side of the drill. Note that although the drill has a positive traversing and rotative mnvenlent, the edge af the mill at e’ must always touch the lip at a given distance from the

front edge, this being the vanishing point. The ather surface forming the real diameter of the drill is beyond reach of the cutter and is left to guide and steady it while in use. The point e, shown in the enlarged section, shows where the cutter commences and~its increase until it reaches a maximum depth at e, where it may be increased or diminished ac- cording to the angle employed in the operation, the line of cutter action being represented by ii.

Before backing off, the surface of the smaller drilis irr particular should be colored with a solu- tion of sulphate of copper, water, and sulphuric acid. This solution can be applied with a piece of waste; it will give the piece a distinct copper color. The object of this is to show clearly the action of the mill on the lip of the drill. When the action is satis- factory, a uniform streak of coppered surface the full length of the lip from the front edge g back to e is left untouched by the mill.

The coloring solution can be made by the follow- ing formula:

Sulphate of copper ( satura~ted solution) . 4 oz. Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807.. Sulphuric acid . . . . . . . . . . . 1 oz.

Some machinists prefer to begin the cut at the shank end. By starting the cut in at this end, the tendency to lift the drill blank from the rest is lessened.

CUTTING LEFT-HAND SPIRALS. For the production of left-hand spirals, the only changes necessary are the swinging of the saddle to the opposite side of the center line and the introtduction of an inter- mediate gear upon the stud (Fig. 45) to engage with either pair of change gears for changing the direction of rotation of the headstock spindle.


Figure 50

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cannot be conveniently cut with side or angular milling cutters, as previously described, it is sorne- times convenient to use end mills. Such instances might occur when the diameter of the piece is very large or when the spiral is of such a lead that the table cannot be set at the requisite angle. In such cases, the work is so held that its center and that of the mill will be in the same plane and the saddle is set at zero.

Lubrication and Maintemmce Procedures

OILING. It is well to remember when applying oil that ordinary bearings can hold only a few drops at a time, and that this amount applied at regular and frequent intervals is far more beneficial than a flood of lubricant at irregular periods. There are so many good machinery oils on the market that it is hard to specify any one as the best to use for lubri- cating a milling machine. Any good coal or mineral oil can be used. Animal oil will gum up the bearing surfaces, oil channels, and tubes, and it has a tend-

” ency to retard rather than render easy the move- ments of the d&rent parts. It is cheaper to buy

good oil than to run the risk of damage to bearings from overheating or scoring.

CARE OF DRWINC CHAIN on MOTOR-DRIVEN MA- CHINES. The chain on motor-driven machines should be kept clean, well lubricated, and properly adjusted. The tension at which the chain should run is ob- tained by a convenient adjustment on the motor bracket. Properly adjusted, the chain should have a little less tension than would be considered right for a leather belt.

tb)VSTMENTS. As parts and bearing surfaces wear, it becomes necessary to make adjustments from time to time, and, at all important points, convenient means are provided for doing this. Flat bearings are provided with tapered gibs that are easily adjusted, and any cylindrical bearings subject to hard wear have adequate means for readjustment. It is essential that any adjustment required be made promptly, for otherwise the accuracy of the machine is impaired. Furthermore, parts wear much more rapidly as the lost motion becomes greater. By a little examination and adjustment every now and then the efficiency of a machine can be maintained and its life greatly prolonged.

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Before proceeding to adjust or take anything apart, it is a good plan to study the machine’s con- struction carefully. Many times this simple precau- tion will obviate considerable trouble. Manufacturers usually provide detaited instructions regarding im- portant adjustments with each piece of equipment. It is therefore unnecessary to give detailed instruc- tions on adjustments in this book.

Figure 51 will be of interest in showing a typi- cal set of instructions for the adjusiment of the spindle bearings of the back gear and sliding gear shafts usually furnished by the manufacturer of the machine.

To adjust the front spindle bearing, loosen screw

A and tighten nut B; tighten screw A after the adjustment.

To adjust the back gear bearing, remove cover D and adjust nut E so that the bearings are snug; then replace cover D, making sure that the locking pin registers in the hole in the nut.

To adjust the bearings on shafts F-G, remove the locks J from the two nuts H and adjust to suit. Replace the locks io each nut.

To adjust the bearing in holder K, remove nut L, bolt M, and lock N. Adjust nut P to suit. Replace lock, bolt, and nut.

When it may be necessary to make adjustments, avoid putting too great a pressure on the bearings.

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Chapter 15


Shapers are used for the machining of flat or plane surfaces which may be in horizontal, vertical, or angular planes, and for the machining of irregular shapes. This machine is indispensable for the ma- chining of jig, fixture, and other small parts. Figures 1, 2, 3, and 4 show the various parts and adjustment of the shaper. Shapers are classified in several differ- ent ways; for example, the name applied to a given design may indicate the action of the machine when in operation, the type of driving mechanism, or other constructional features. The two types of shapers commonly used in machine shops, toolrooms, and production plants are the horizontal and the vertical (Figs. 2 and 4). The size of the shaper is designated by the maximum length of its stroke given in inches.

On shapers, the work is held on a table 01 knee, and the tool is held in a tool post on the reciprocat- ing ram by means of which it moves across the work. The knee has both transverse and vertical adjust- ments and is provided with hand and power feeds.

I- -I

Figure 1

These machines are particularly adapted to small work of the kind usually held in a vise. The length of the ram stroke is adjustable, and the work can be readily shaped close to the shoulder because the length of stroke of the ram is positive.

Vertical shopem

The vertical shaper (Fig. 5) is generally consid- ered a heavy-duty machine. It is usually used to pro- duce work that cannot be handled on other types of machines. The rated size of a vertical shaper is given in terms of the stroke of the ram. Sometimes the diameter of the table is given to ascertain the &e of the work a particular machine is able to handle, similar to the swing of a lathe in order to specify its rated size. Since vertical shapers are gen- erally designed and constructed for special opem- tions, it would be impractical to give the procedures for operating this type of shaper. Modern horizontal shapers, however, are in general use, and the opera- tion procedures of this type of shaper are, to a great extent, standardized.

Iio?tzontal Shapers

The horizontal shaper shown in Fig. 6 is a modem universal type. It is equipped with a revolving table with a tilting top that revolves at any angle. The table has one solid face and one tilting face with adjustments up to 15 degrees either way on an axis at right angles to the trmmion of the machine. Each movement is made by a crank wrench through a worm wheel, and all settings are indicated by gradua- tions. The swiveling vise that is usually furnished by the manufacturer permits the machinist to rotate the work around three possible axes.

POWER RAFWJ TRAVERSE. Where some jobs have to be performed at speciRc speeds, the power rapid


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Figure 2. Crank-driven column shaper.

Figure 3 Figure 4

Various parts and adjustments of a shaper shown in Figures 1-4. (A) Clapper Box, (B) Down-feed Handle, (0) Head, (D) Head Swivel Lock Screw, (E) Ram Clamping Handle, (F) Ram, (G) Switch Box, (H) Hand Wheel, (1) Drive-pulley Guard, ( K) Motor, (L) Motgr Cradle, (M) Tension Release Lover, (N ) Eccentric, ( 0 ) Feed Rod, (P) Table Elevating Crank, (Q) Cross Feed Crank, (R) Cross-rail, (S) Base, (T) Work-table Support, (U) Support Locking Handle, (V) Work Table, (W) Vise, (X)Lamp, (Y) Tool post, (Z) Tool holder, (2) Motor Pulley Guard, (3) Column, (4) Cover Plate, (5) Gib Ad- justing Screw, (6) Gib, (7) Motor Cradle Adjusting Screw, (8) Elevating Lock Handle, (9) Adjustable Wrench, (10) Tail-stock Wrench, (12) Clapper Block, (13) Feed Lock SC~CW, (14) Feed l$,wl, (1.5) Counter-&It, (16) Counter-shaft l’ulle~, ( 17 ) Counterbalance Adjusting Screw.

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This gives compact and powerful transmission that is practically noiseless and accessible at all times.

Fmm. The feeding motion in modem shapers is actuated by a series of cams. This gives a smooth, rather than an abrupt, movement and enables the entire feed under any condition to be confined within the return stroke.

The thrust bearings on each end of the three feed screws reduce the friction at these points and make hand feeding easy. Another feature is the omission of the usual feed box on the end of the cross rail. This is transferred to the side of the column of the ma- chine. Eleven feeds ranging from ,010 to 270 inch (MIS to ,085 inch optional) are provided. The amount of feed is controlled by the machinist by means of a lever that is mounted on a direct reading dial which indicates the feed in thousandths. Three- quarters of one turn changes the feed from minimum to maximum. A second lever for feed engagement has three positions marked stop, right-hand, and left- hand, indicating the direction of the table movement. All feed changes may be made while the machine is running.

Figure 5. Vertical shaper,

traverse is a valuable addition to any shaper. Time is saved when the p&z is finished because the power rapid traverse can be quickly traversed to one side without taking time to crank the table. The work can be unloaded without interference of the tool and the post.

LENGTH OF STROKE. In modern machines, the length of the stroke is maintained without the usual clamp- ing nut on the stroke adjusting shaft> the purpose of the nut being fulfilled automatically. The length of the stroke can be changed while the ram is in motion. The indicator dial shows the setting for the length of the stroke at all times, whvtheer the ram is in motion or stopped. A guard covers the stroke adjusting shaft.

The quick traverse operates directly off the drive pulley of the machine. It is actuated by a lever and is always available to the machinist. Five antifriction bearings are used in mounting the shafts which bring the quick traverse to the tabIe. A safety crank hangs free in place during rapid traverse, ready for instant use in hand feeding; it is also used by the machinist for rail elevating and lowering. The same lever engages and controls the direction of tbe table during feed and also controls the direction of the power rapid traverse.

TRAXSMISSION. Changes are made by two levers within easy reach of the operating position. They are on the speed indicator usually attached to the machine. The ease with which speed changes can be made encourages the machinist to use the correct cutting speed. The gears in a modern shaper are placed entirely within the column of the machine. Figure 6. Universal shaper.

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RAM. The ram is a V-type. Adjustment is made with a full-length ::L~.Y gib that is controlled by a single screw. The c;~~rinuous full-length tap:r gib affords a solid bearing and forces the ram to wear straight, Adjustments can be made quickly and easily. Another advantage is that the length of tbp ram bear- ing is the same length as the ram its& ‘hs, the extension of the ram bearing out to the a >.:i*, el head reduces the overhang from the ram to the t,z! to an absolute minimum. The movement of the ram clamp lever is limited in its open position, and no damage can result to the ram positioning screw.

COLUMN. Both sides of the column top (the ram ways) are built to form a solid part of the column casting, adding to the rigidity of the column. The colrmn throat is closed by a guard so that chips can- not be swept off the work into the shaper.

TOOL SLIDE. The tool slide is solid and fits into the swivel instead of clamping around it, thus avoiding the open or hollow form with its spring and breakage under overload. The guides in the tool slide are fitted with a taper gib having a single-screw adjustment, The tool head is graduated; when it is swiveled to any angle, it can be clamped by using a T-slot in the ram. The feed screw is fitted with a micrometer dial graduated to thousandths. The tad post is made un- usually large and is provided with a specially hard screw of the same size as the screw on tbe vise of the machine. This permits the use of the long vise range when it is necessary to tighten large tools in the tool slide. The tool slide has a clamp screw which assures a set position of tbe tool for horizontal surfacing and acts against the gib. This prevents burring the tool slide.

CLAPPER Box. The clapper box in the modern ma- chine is constructed of steel instead of cast iron. The clapper and the serrated tool plate are made in one piece and hold the clapper.

CRANK GEAR. The crank gear is made in one piece witb helical-cut teeth (Fig. 7). This type of construe- tion insures long life to the crank gear plus finishing cuts that are always free from gear-tooth chatter marks. The crank gear is usually located as near as possible in the column of the machine without cut- ting the ram bearing, and it fits beneath a guard cast with the column.

ROSEB ARM. The rocker arm (Fig. 8) is made :rn one piece, fulcrumed at the bottom, and connected to the ram of the machine by a steel link. Both the fulcrum and the link pins are hardened and ground.

CRANK HLOCK. The crank block is held in the

Figure 7. Crank gear.

Figure 8. Rocker am.

dovetail slide of the crank gear by a taper gib and is made of drop-forged steel with a hardened and ground pin (Fig. 9).

SLIDING RLOCK. The sliding block is made of gray iron with a hardened and ground steel taper gib on its driving side to compensate for wear. Therefore, there is a hardened steel crank bearing in the gray iron sliding block and a hardened steel crank block gib bearing against the semisteel rocker arm, thus

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Figure 9. Crank block.

affording ideal bearing conditions. If the shaper is used on a great variety of work-some long and some short-the wear will be cxoparatively uniform over the entire sliding surface of the rocker arm, and adjustment for the wear can be made with the taper gib which is on the driving side of the crank block.

COMPOUND CROSS RAIL. The compound cross rail is square-locked to the column.

APRON. The apron is secured to the long and narrow guide of the cross rail by taper gibs at the top and bottom. It is provided with T-slots for hold- ing the work when necessary. These T-slots do not run across the entire width; they leave reinforcing ribs at the center and the sides, making a solid wall

Figure 10. Cast i-on cutting tools.

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Figure 11. Mild steel cutting to&.

Figure 12

Figure 13

apron ,and a much stiffer member. A slot is also placed across the face of the apron for the proper alignment of fixtures.

TABLE. The table is a full box form having small openings in the front and the bottom. Two bolts fasten the table at the top of the apron, and four bolts secure it to the front. The spacing of the T-slots in the table is made so that the vise will fit either the top or the side of the table.

Cumm Tocw AND Ho~u~ns. The straight-shank tool M&r holds the tool parallel with the front and rear surfaces of the tool holder. Since the tool is held parallel with the surfaces, it is at right angles to the direction of the stroke. Thus, the clearance angles which are needed for cutting are easily deter- mined and ground without having to take into con- sideration the inclined angle of the tool. With the adjustable head of the tool holder, the tool may be trwned either to the right or the left, still maintaining the same attack angle to the work. The shape of the tool varies with the character of the work. A number of tools generally used are shown in Figs. 10 and 11. The shape or form of the tool depends upon the shape of the cut, the kind of finish required, and the kind of material to be snachined. The rake, the cutting angle, and the clearances depend upon the nature of the material.

Figures 12 and 13 show the terms to dcsignatc

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HORZZONTAI; SHAPERS 341 I the parts of a single-point cutting tool and the working angles used in grinding them. The following terms are accepted standards used in connection with shaper cutting tools:

The point is the part of the tool which is shaped to produce the cutting edges and face.

The shank is the part of the tool on one end of which the point is formed or the bit i,s supported. The shank, in turn, is supported in the tool holder of the machine.

The face is the surface of the tool on which the chip rolls or flows as it is cut from the work.

The cutting edge is the portion of the face edge along which the chip is separated from the work; it consists of the side-cutting edge, the nose radius, and the end-cutting edge.

The shape of the tool is the contour of the face when viewed as presented to the work.

The working angles are the angles between the tool and ,i:he work which depend on the shape of the tool and on its position with respect to the work.

The cutting angle is the angle between the face of the tool and the surface to the machined surface at the point of cutting. It equals 90 degrees minus the true-rake angle.

The Zip angle is the included angle of the tool between the face and the ground flank measured in a plane at right angles to the cutting edge. When measured in a plane perpendicular to the cutting edge at the end of the tool, it is called the end-lip angle.

The back-rake angle is the angle between the face of a tool and a line parallel to the base of the shank.

The end-relief angle is the angle between the por- tion of the end flank immediately below the cutting edge and a line drawn through that cutting edge perpendicular to the base.

The side-rake angle is the angle between the face of a tool and a line parallel to the base.

The true-rake angle is the slope of the tool face toward the base from the active cutting edge in the direction of chip flow. This angle will vary with the setting of the tool and with the feed and the depth of cut.

A right-cut single-poi,nt tool, w&n viewed from the face, has the cutting edge on the right side (Fig. IO).

A left-cut tool has the cutting edge on the left when looking at the face (Fig. IO).

The shape of the tool may be curved, fiat, or its sides may converge to a sharp point, depending upon the surface being machined.

There is usually a difference between the rough- ing and the finishing tool. In addition, a tool may be offset, or bent to the right or to the left, and may feed either in a right-hand or left-hand direc- tion (Fig. 10).

Although the contours of shaper tools are gener- ally similar to lathe tools, they differ in their clear- ance angles. Lathe turning tools are usually ground with a front clearance of 10 to 12 degrees, and are set above the center so as to have the effect of 2 or 3 degrees of working clearance. Since there is no rocker in the tool post of the shaper, the shaper tool cannot be adjusted for clearance, and the cor- rect clearance angle must be ground on the tool itself. The clearance angles of shaper tools generally used, shown in Figs. IO and 11, are as follows:

The roughing tool is similar in contour to the lathe turning tool. It has a side rake but no top rake, and the amount of side rake depends on the hardness of the metal being cut, the harder the metal the less the rake. They are usually used to cut to the left, but they may be ground with the proper clearance and rake and used to cut to the right.

The roundnose tool is used for cutting down; its cutting edge is the widest part of tbe tool; the corners are slightly rounded for longer life; and it cuts down equally well on either :be right or the left side. This tool may be used with a very light chip, a coarse feed, and a slow speed for finishing horizontal cast- iron surfaces.

The squarenose tool is available in any desired width for roughing and finishing sides and bottoms of grooves, keyways, and shallow shoulder cuts. The cutting edge of this tool is the widest part of the blade.

The spring tool or “Gooseneck” is used, for finish- ing cast iron. In using this tool, there is less tendency to chatter and to “dig in” than with the shovel nose.

The downcutting tool is made in the shape of a left-hand roughing tool except that it is bent in order to cut down on a vertical surface.

Side tools are made for both right-hand and left- hand cuts. They are used for finishing vertical cuts and occasionally for Ilnishing a narrow, horizontal cut adjacent to the vertical cut.

RIGHT-HAND AND LEFT-HAND TOOLS. Figures 10 and Xl show that some shaper tools are both rigbt- hand and left-hand. When a job is being set up in a machine it is advisable to arrange the work and the cutting tool so that the cut can be observed. When taking a horizontal cut on either a shaper


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or a planer, start the cut on the side toward the machinist. When shoulder cuts or cuts of a similar nature are made, the work must be arranged so that these cuts will come on the side toward the machinist in order to observe the action of the cutting tools.

A great many shaper jobs include the cutting of tongues, grooves, and angles, and they involve cuts on both sides of the work. To assure greater accuracy and speed in one setting df the work, all the surfaces require right-hand and left-hand tools. The terms, right-hand and left-hand, are derived from lathe tools of similar shapes.

TOOL HOLDERS. The forged tool has been super- seded to a great extent by the modern tool holder and the modern high-speed steel bit. There are dis- tinct advantages to using the tool holder, for the tool bit can, easily be ground to the required shape to accomplish any specific operation. Several types of tool holders are available, and their general con- struction permits the tool bits to be securely and rigidly held in any position so that right-hand or left-hand borixmtal, vertical, or angular cuts can be made. When heavy cuts are to be made, these tool holders can be reversed in the tool post. Tool bits are reversible. The cutting edge will be back of the shank of the tool, and any tendency to dig in or to chatter is eliminated.

Holding the Work

Shaper operations are performed on small pieces; therefore the work is held either in a vise or a chuck. Vises or chucks are auxiliaries to the machine, or specifically to the platen, or the table of the shaper. Pieces that are too large to be held in a vise or a chuck must be fastened directly to the platen or table of the shaper. When clamping the work to the table of a machine, tighten the ciamp bolts so as to hold the work firmly on the table to avoid any


Figure 14

Figure 18

distortion or spring. The method employed to secure the work is to a great extent dependent upon the type of job to be machined. The work can be fastened by bolts, clamps, stop pins, stop pins and toe dogs, stop pins and strip, special strip pin block and stop pins, or indirectly with a fixture.

BOLTS. A complete bolt assembly consists of a bolt, a nut, and a washer (Fig. 14). Table bolts are equipped with T-heads of a size to fit in the table slots. The bolt should always have an ample length of thread to adapt it to work of various thicknesses. ,A clamping unit consists of a bolt, a bolt assembly, a clamp, and a fulcrum block (Fig. 15).

CLAMPS. When using clamps, position the work on the table close to tbe table slot so that the bolt will be as far as is practical from the fulcrum block. Be sure to have the bolt near the work, and screiv the nut enough to anchor the work properly. Do not ,screw the work too tight, for this will have a tend- ency to spring it.

Where a number of clamps have to be used, pro- ceed as follows: Turn the bolts until the work is lightly clamped. Then tighten the bolts in the se- quence as shown in Fig. 16; this will distribute evenly the stress that is brought on the work during clamp. ing.

Select a block of the same thickness as the part that is being clamped when fastening the work to the shaper table. The end of the clamp wilt then have an even bearing on the work, and the work will lbe held more securely than if the clamp were bolted

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Figure 17


Figure 18

,by using a block that was either too high or too low. ‘,, The effect of low fulcrum blocks is shown in Fig. 17.

STOP PINS. Stop pins are one-leg screw clamps. They are anchored in one of the table holes or slots.

‘The screw can be forced directly against the work or used in conjunction with some other device such as a toe dog to force it against the work (Fig. 18).

STOP PINS AND TOE DOGS. When working on thin stock, stop pins are used in combination with toe dogs as holding units (Fig. 19). A toe dog is a holding device (Fig. 20) similar in shape to a center punch or a cold chisel. It is designed to be forced against the work by a stop pm (Fig. 19). Stop pins are inserted in the table on each side of the work, and the dogs are forced against the work by tighten- ing the stop pin screws. The end of the stop pin screws projects into the short bore in the end of the toe dog, thus connecting the two parts. The work is pressed against the table because of the angular position of the dogs. The angle between the screw and the dog must never be too great. The work must be anchored by a number of stop pin toe dog units to take the thrust properly and secure the work to the table.

STOP Prws x.m Srrun. A combination of stop pins and strip is usually adapted to hold down rectangular work of suillcient thickness to project above the strip and stop pin screw (Fig. 21). This combination has a tongue on one side which fits in the table slot and positions the work so that it is parallel to tbe travel of the tool. Figure 2i shows the strip upside

down to illustrate the tongue and holes that are pro- vided for slot bolts.

The procedure for using this combination is as follows: Place the two bolts in the slot, insert the strip tongue side down so that the bolts will pass through the holes with the tongue projecting into the slot, and then secure with the nuts. Put the stop pins into the table holes, and screw them firmly against the work with the strip aligning the work parallel with the tongue of the cutting tool of the shaper. Suitable stops must he provided to take the thrust of the cutting tool.

BRACES. One or more braces are required to take the thrust of the cutting tool where the work that has to be machined projects high above the table of the shaper. When machining work of the type shown

Figure 19


Figure 20


5Lo --iii5



Figure 21

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in Fig. 22, the thrust of the cutting tool will tend to rotate the casting around the point marked, A, Fig. 22, as the center, indicated by the curved arrow. A properly placed brace will offset that tendency. Tbe clamp at point A, Fig. 22, will resist the tendency of the casting to move upward in a circular path around the point marked B, Fig. 22, as center. By placing the clamp bolt at point A against the lower flange, the clamp will act as a lower stop, and the work will be securely stop-anchored on both the upper and the lower flanges. The number of braces

Figure 22

Figure 23



Figure 24

Figure 25

required will depend upon the size and shape of the work.

%%CIAL STOP PIN BLOCK AND STOP PINS. A special strip pin block and stop pins are used to hold circular or round stock. The setup shown in Fig. 23 should provide a rigid anchorage.

In this type of work, a special strip having one side marked A inclined toward the work is used. As with the ordinary type of strip, the tongue which fits into the table slot of the machine insures parallel- ism. The holding unit at the right is a block with one side marked B inclined toward the work, with a distance filler piece plus a stop pin. The axis of the stop pin shown at C, Fig. 23 must always be higher than the center of the work as shown at D, Fig. 23. Under these conditions, the work will be forced firmly against the table at all times when it is clamped with the stop pin. Assume in clamping that the stop pin in axis C is at an elevation below D, as indicated by C. The wedge block would then simply rotate as shown by the dotted curved arrow marked E. On general production work where such holding devices as the strip and block are employed, they will be specially designed to give the most efficient clamping. A thrust-resisting stop must ai- ways be included in any shaper setup.

Another method of clamping a shaft in which the table slot instead of a strip insures parallelism and L-clamps and stop pins are used is shown in Fig. 24. This method is adapted to shaper tables having transverse slots.


TABLE. A typical example of the setup for mounting irregular work indirectly to the table is shown in Fig. 25. A fixture for holding and positioning the work that is being machined is used. In Fig. 25 the fixture is an angle plate that is fastened to the table on one side, and the work is fastened to the other side of the plate. Since the casting projects a dis- tance from the angle plate, provision is also made in this setup for supporting it on wedge blocks so

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as to prevent a spring. The clamps are in line with the wedge blocks so that they can be seen by the mechanic, but in an actual machine shop setup they would be shifted about 90 degrees to make the wedge blocks more accessible for any adjustment that might be necessary.

The wedge blocks must not be forced together too tight as tc spring the casting, but just tight enough to give adequate support. This condition can be ascertained by testing with a surface gauge and previously scribed marks. Figure 25 shows that the angle plate acts also as an efficient stop.

HOLDING THE WORK WITH A VISE. The machine vise is designed to attach to the machine table. It consists of a base, table, and stationary and adjust- able jaws. Two general types are used in the shaper; the plain vise which can be single- or double-screw, and the universal vise.

The plain vise shown in Fig. 26 is equipped with a base that has a tongue to fit in the machine table slot and lugs or open holes for bolting to the table with the T-head bolts. On the base of this vise is a circular gauge that is graduated in degrees to indicate any angular position in which the jaw tabie is turned. The table of the vise has a stationary jaw at one end and ways on which the adjustable jaw moves.


Figure 26


Figure 27


Figure 28


Figure 29

It also carries the clamp screw. When clamping the work in the vise, the movable jaw should be brought into position to engage the work.

When a thin piece of work placed in the vise pro- jects above the jaws it has to be raised high enough by resting it on parallel strips so that the jaws of the vise will not interfere with the cutting tool (Fig. 27). If the piece of work is long and narrow, the vise should be turned above 90 degrees so that the cutting tool of the machine will take long strokes rather than a number of short ones.

Where it is necessary to place round work which is too small in diameter to rest on the vise ways, the work can be held in horizontal alignment parallel with the vise table by using suitable V-blocks (Fig. 28).

The procedure for clamping an odd-shaped piece is shown in Fig. 29. Ordinarily, the jaw on the con- cave side wguld not get a good grip because it wouId make contact only as shown at A, Fig. 31, and would tilt the work. This coxlitiox GUI be avoided by using a round rod as shown in Fig. 29.

Figure 30 shows a wedge-shaped piece clamped in a vise of the universal type. If the angle of the inclined side of the work is too great, a stop is neces- sary to prevent the work from shifting sideways.

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Figure 30


Figure 31

When the movable jaw of a vise is forced against the work, the jaw will raise and lift or even sometimes tilt the work. The jaw will invariably conform to the irregular sides of the casting so that the opposite sides, when machined, will not be true; this can usually be avoided by using a round rod in the clamp- ing setup as shown in Fig. 31. If the jaw drifts, it will cause the rod to roll from position A, Fig. 31, to the dotted position B, Fig. 31.

FUNCTIONS OF SPECIAL FIXTURES. Special fixtures are designed and used in conjunction with the ma- chining of irregularly shaped castings and where the quantity production and machining of a large number of identical pieces is required. The basic requirement is that the fixture must position and support the casting in the right places to prevent any stresses which may spring the casting due to uneven clamping. These fixtures must be constructed so that castings can be attached to them without loss of time and effort.

FUNCTIONS OF SIJ&PER CENTERS. Shaper centers are employed for finishing work that cannot be com- pletely machined on lathes. They are similar to the headstock and tailstock of a lathe except that the heudstock spindle rotates only when turned to a

desired angular position as determined by an index head.

Work partly nrzhined in the lathe, when finished in the shaper, is placed between the shaper centers. The same centers are used on the work that were used when it was turned on the lathe. Shaper center-s are constructed with a tongue on the base. This tongue fits in the shaper table slots and insures parallelism and correct alignment (Figs. 32 and 33). The alignment of the centers should be carefull! checked before the machining operations are started.

HOLD-Downs. Hold-downs or grippers are gener- ally used to hold down thin pieces of work in the vise of the shaper. They are made of thin pieces of triangular cross sections of required lengths. The narrow edge of the hold-down is usual!y rounded, and the opposite edge is beveled to about two de- grees toward the bottom as shown in Fig. 31. The) are especially valuable when thin material has to be held down on the bottom of the vise or on a parallel. Hold-downs are useful when parallels of a height necessary to raise thinner pieces jnst above the vise jaws are not available in the machine shop. They are also employed when only two opposite surfaces of a piece require finishing.

Figure 32

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Figure 33


Figure 34

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Chapter 16

Fundamental Shaper Operations

To start the modern shaper shown in Fig 1, put the change gear shift lever in the neutral position. The stroke dial should read zero. Then put the feed lever into neutral. When starting the motor, make certain that it is running in the proper direction. Arrows on the belt and pulley guard show the COT- rect direction. Engage the clutch lever with the gears in neutral and the stroke at zero, allowing the shaper to run from three to five minutes to fill all the oil tubes before the ram is set in motion. Oil should be visible to the machinist in the sight feed station pro- vided at the top of the column of the machine. Be sure that the rocker arm and the siiding block are getting sufficient oil. The oil pressure gauge should read 50 pounds when the clutch is engaged.

General Opemiing Procedures

In the type of machine shown in Fig. 1, the stroke is adjusted by turning shaft 8 with the crank that is furnished with the machine. The stroke adjusting shaft is self-locking. The length of the stroke is shown on the dial at 5, Fig. 1 whether the shaper is in motion or has been stopped. When necessary, the ram is unclamped by the lever (6, Fig. I), and is adjusted to the required position by turning the shaft (2, Fig. 1). The same crank is used for positioning the ram and for adjusting the stroke.

If the slide has been set at an angle, do not run the ram back into the column until the slide has been set straight again.

There are eight speeds shown on the direct read- ing selector plate. Four speeds are obtained by means of the lever shown at 9, Fig. 1. Four additional speeds are obtained through the back-gear control lever shown at 7, Fig. 1. For all surface cutting speeds, refer to the tables on specific cutting speeds usually furnished by the manufacturer.

The lever shown at 4, Fig. 1, regulates the amount

of feed transmitted to the table. The automatic feed is engaged and disengaged by the lever shown at 3, Fig. 1. This lever is directional; it shows the direc- tion of the table movement whether employed fog feed or for power rapid traverse.

To prevent breakage to the machine in the event that the table should run against an obstruction, a safety clutch is provided for both feed and power rapid traverse.

VERTICAL ADJUSTMENT OF THE TABLE. To adjust the table in a vertical direction, unclamp the rail by putt@ a large wrench on the shaft (1, Fig. l), and pull it toward the front of the machine. Loosen the table support nuts (13, Fig. 1). Remove the safety crank (12, Fig. 1) from the cross feed shaft atid engage it on the elevating shaft (II, Fig. 1). Remove the crank by placing the clutch teeth opposite each other and pushing the crank. Raise or lower the table to the desired position and r&amp the rail by tarn- ing the shaft 1. Tighten the front table support by pulling up the nuts, shown at 13, and at the same time be sure that the apron is centered on the rail to prevent cramping. The large hexagon head cap screw holding the rail clamp at each side of the column of the machine must always be tight. The socket-head cap screws should never be disturbed.


TRAVEXSE. To operate the horizontal power rapid traverse (Fig. 2), place the feed lever j in the direc- tion of the desired movement and raise lever KK.

To operate the vertical power rapid traverse, loosen clamp shaft L, Fig. 2, and loosen the table support bolts (13, Fig. 1). Place feed lever J, Fig. 2, in neutral, place lever JJ in the direction of move- ment, and raise lever KK. Always use the head feed for feeding the table.

OPERATION OF CLUTCH. The shaper shown in Fig. I is equipped with a modern electric clutch and brake. Finger-tip control and braking of the ram


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Figure 1. Shaper operating points. (1) Rail clamp control, (2) Ram positioning shaft, (3) Cross feed engagement lever, (4) Power cross feed selector, (5) Stroke indicator dial, (8) Ram clamp lever, (7) Back gear lever, (8) Stroke ad- justing shaft, 9) Genr shift lever, ( “I) Power rapid haverse lever, (11) Rail elevating manual control, (12) Cmss feed safety crank, (13) Table support clamping nuts, (i4) Power elevating engagement lever, (15) Glntcb znd brake switch lever, ( 16) Tool post, ( 17) Clapper clamping nuts, ( 18) Tool slide crank.

movement is convenient and fast for both setup and operation. No adjustment is required on the elec- trically operated clutch and brake (Fig. 3).

The control switch furnished by the mar.ufacturer is standard. Duplicate controls are available for the opposite side of the machine. A foot control or port- able control can be used if required.

CUTTING SPEED. The cutting speed on a shaper is governed by the length of the stroke and the strokes per minute. For the same strokes per minute, the cutting speed increases as the stroke is lengthened. Avoid operating the shaper on excessively long stroke at high speeds. A diagram showing a typical full stroke is shown in Fig. 4. The cutting speeds in feet



Figure 2. Power rapid traverse.

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Figwe 3. Cltitch and b&k.

Figure 4. Diagram for typical full stroke.

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per minute for the different strokes per minute an3 various iengths of strokes for various sizes of shapers are shown in Table 29 below and in Table 35 in the Appendix.

Tal3l.r. 19 ~,.,.o\v~,BLE CUTTIYG SPEEDS-FSST PER Mm’um

RIG” SPEED STEEL TOOLS ~hterial Roxghing Finishing

Cast rrnn 60 100 .I@ t” .20 c so 120 .%I to .40 c 60 130 Die Steel 40 40 Hard Bronze 60 1.00 3rz?s5 150 .liar. Speed .&minun 150 Max. Speed

~~:~i\-rm;rl tables itI combination with the swivel \ i,;t, f~~n~islwd with the machines permit the work to !il. rot:ited ~lround all three axes. This type of table is esprciaily useful in tool arid die shops. It is rotated hy iirsc loxening the four nuts at 6&e front oi the table 2nd then operating the shaft (AA, Fig. 5). the crani- for this shaft is the same as that used for the ram and &r&e adjustmeat. The plain face of ihe table is brought into position by rotatins the t&k c!ock .I.__ -=-.~~~ irice 2oainst the stop. The ti1Fir.g face is brought into the required working position using the graduations an the front of the table. After the table is rotated to rhr proper position. tighten the four nuts on the front of the table.

The- tilting face of the t&Be is adjusied by first looseriing the clamp rruf; 3B and CC, Fig. 5. Adjust the fxe to the desired angle ‘iby operilting the shaft DE)> Fig. 5, with FYae crank. Crairuati:,ns on Fbe side nf the tilting fxe towd the front show the angle of the tik The tiking face shcmld then be secured in position by tightening nut CC iirst and nut BB last. a’; shown in Fie. 5. The r.u;t CC apemtes the xedges to serrt 2.. ‘tiiting &me ier iFs f&scraped bertring. acd nut BEG clamps it securely in position.


Figure 5. Uoiversnl table.

Oil the skew as required around the shaft (AA, Fig. 5) at the point marked for oil. Keep the scraped bearing surfaces of tilting face of the table and the scraped bearing between the apron and the rotating table clean and oiled. On the universal shaper with a table support, be sure to keep the slide clean, and oil daily at the point provided near t!le bottom of the table support.

To se the automatic down feed to the bead (Fig. 6), first set tht: stroke for length and positior. Stop the rm at md~troke. Then locate the cam bracket in the approximate position on the column for the end of the return stro!=e. .4ltemately stroke the ram and adjust the cam bracket until the required feed graduation coincides with the zero mark on the bracket mounted on the ram. The smali clutch lever starts and stops the power dowx feed. For different depths of cuts, use the positive stop on the Read of the machine. Fill the oil pocket io the bracket r~twrrnted on txn diiily ii the power doam feed is wc:tP d;dy, otherwise oil 85 required.

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Tool L&r >peration


) : .,-23~r~~

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Figure 10. Head adjustments.

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square as shown in Fig. 18. Arrange the indicator as shown in Fig. 18, and move the work table the distance from A to B. If the indicator shows the same registration at both ends of the blade, then the jaw is square. Try the jaw near each end and in the middle; it may be necessary to shim the jaw until it is absolutely square.

SETTING THE VISE PARALLEL wrr~ ‘THE DIRECXON 07 THE STROKE. The graduations on the swivel plate of the &per are usually accurate enough for prac- tically all jobs. Occasional!y, however, a shoulder must be cut exactly parallel with the edge located against the jaw or the work will be spoiled. To make the test for this position, arrange the length of the stroke to the length of the jaw holding the indicator in the tool post, and run the shaper slowly by band to see if the indicator reg:sters the same at botb ends of the jaw. If any aJjustment is necessary, the vise should be clamped lightly and tapped with a babbitt hammer until the setting is wrrect. The vise should then be clamped tight and tested again before pro- ceeding with the actua! job.

SElTlXG TEE \h3 SQUARE WIT11 THE ,,lREC~ON OF TIE STROKE. To set the vise square with the direction of the stroke. and to correct the setting if incorrect, the indicator should be arranged as shown in Fig. 18. The \-ix is turned 90 degrees. and the worktable is moved by band to show the movement, if any, of the indicator wzedle.

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Figwe 17


TAWNC ~IOIUUIN+AL (Iurs. When the work is fed in a horizontal ~~~r~~~~ under the reciprocating cutting tool of tire stqm, the result, depending on the tool used. is a ~~~~t~~ dot or plane surfxur. Th hgtb of the stroke in a shaper is set approxi-

n the work. The position of that a, in. of this extra length

of the cut to allow the tool or ahr mr:xt cut.

~ta~~~fa(~M~~q ad cr,r&ntet the clapper blwk WP that it titr abe beas., met tx%lring surfau!s arc srrapld to pwi& tt6z Ew4t sliding fits. with tlic axis of &r $ringe pin at ri&t aa&s; the block

The cut is usually started on the right side in order that the depth of the cut, the action of the tool, and the other movements can be radily ob-. served by the machinist. The feed of the table should br arranged to move the work toward the machinist on the return stroke, and the left-h;uvl tool should be used.

Hold small pieces of work, or p&es that will tend to tip up at the pressure of tht cut, rith the v&e jaws at right angles to the thrust. Wtth the excep- tion of the cutting speed> there is practically no difference in roughing steel or cast iron on the shaper. For rougcing plain surfzpes of cast iron or steel, use the roughing t- or L tool bit that has been ground to a similar .LP; z and held in a suitable holder. T!~:- tool shouid be clamped in a vertical position and pointed a very little in the direction away from the work so that, if the tool moves due to the pressure of the cut, it will move away from the surface instead of undercutting the work.

ADJUSTING THE WORK. After ne job has heen mounted and properly aligned on the table of the shaper, the first operation is to move out the ram so that the tool post carrying tJ)e cuttiirg tool is directly over the work. Then place the tool that is to be used for the job in the tooi post, making cer- tain that there is very little overhang. Elevate the table until the work clears the ram of the machine by about one inch. The tool slide should project very little below the bottom of the head, and the over- hang of the slide should nev-er be over lvi inches. If more than this is necessary, the tool rather than the slide should he set ‘or the extra overhang. .AFter this preiirninary adjustment. the tool should be clamped firmly. Be sure that it clears the work.

AI~JWTSWW OF THE STHOKE. ‘Two necessnn, ad- jrmnents must now be made, those of the length and the position of the stroke. To adjust the length of the stroke, turn the stroke adjustment screw right or left for a longer or n shorter stroke. On modem shaper machines, a handle is provided for the square 1,nd of the adjustment screw with a lock nut. To make the r~rcessiary adjustment for a longer stroke. the adjuitmcnt screw on some types of m;lchincs nrust be turned clockwise On other ouchines the> are turned collrlterclockwist,. Specific tlircrticms for ttrtw acljnstromts are wt~ally !+upplierl b)~ the m:o~o- fxlamr. If they are not ;Iv&blc. tla:y cari bt. clrtcrrnined by te9ting.

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necessary, until the stroke is long enough to clear the work. This clearance should not be less than dpproxi- mately $4 to */z inch on the forxud stroke, with enough on the return stroke to emz’n.: the automatic feed of the machine to functim betore the tool acto- a!ly comes in contact with the work 011 the cutting stroke,

The feed should function at the end of the return stroke: rather than at the end of the forward or totting stroke. After the length of the stroke has been adjusted, position the stroke so that it over- rravels the work at both ends as specified above. Then loosen the ram clamp and torn the stroke position adjustment shaft in the requLs<! direction. This will move the ram into the rc,iGred position. After the strckc has been properly +3sitioned, the ram is !ocked b!s the ram clamp.

The table must be r.loved b:.; the hand cross feed screw either to the +t tir to the left, depending on the type of tool use& cntii the work is in posi- tion transversely to begin the GIL Tke table shnuld be moved far enough to make one or two test strokes after 21e stroke is adjusted and before the actual cutting is begun. The tool most then be set to the required depth for the first roughing cut by the vertical feed.

T.unhc THE CUTS. After the adjustment of the work to the approximate position has been made, the machinist must decide the nomber of cuts that will he necessary. This depends largely upon the amount of metal that has to be removed. One or two roughing cuk plus one or more finishing cuts are the usual practice, depending on the nature of the job and the finish desired.

The first cut must he deep enough to remove the seal, thus truing up the surface of the work. This gives the machinist an opporhmity to check the setting of the tool. The next step is to take the neees- sary roughing and Wbing cut, but before doing this, the machinist must make certain that the cutting edge does not pr@ect too far from the tool post; in other words, the work must be clamped tight. See that the tool bead &de has not NO down too far, for this position will cause we~akness and undue strain. R,aise Ibe w k r&w than allow the twt Slid@ to projc?6 the head or have the tool project tm far.

~~~K~n planing cast 1, btwl the edge at the ma 5f the cut wittt a se! or an old file to about

of the cut that will found that chunks surface, thus leav-

ragged. Cast-iron scale

is hard and gritty; when working on thk type of metal, make certain to set the tool to take a chip that is deep enough to get under the scale of the cast-iron casting. If a portion of the surface is found to be low during the cut and the tool rubs on the scale. the cvtting edge of the tool will soon he useless.

Finishing cuts must always be light, especially when finishing either steel or Nrought iron. A rather fine feed will giLv the most satisfactory results. The accepted commercial fin& on flat cast-iron pieces is a surfac u that feels smooth to the hand and shows t’le feed marks spaced about $4 in. or more apart. ‘,‘his type of finish is obtained by the scraping action of a broad square-nosed tool which can be either a forged tool or a tool bit that has been fitted to any one of a nunber of types of tool holders, and which may be ground to shape. The best tool holder arid tool for this puTpose is the spring tool because it does not dig in:o the work; a slow speed and a hand feed should be used with this tool.

Oil should be kept 08 cast iron; even oily fingers may spoil a good finish.

SELEC;CTING THE PROPER FEED. When setting the automatic feed, the amount of feed will depend upon the kind of metal that is being machined.

PROPER Currrhic SPEED, Similar to lathes and other types of machine tools, a number of speeds are pro- vided on the shaper. High speeds should be used on short stroke operations, and slower speeds should be used for longer strokes. Since the action of a shaper tool is intermittent and not continuous like the tool on a lathe, higher speeds can be used on the shaper, for the heating of the tool is not so severe. (See speed tables in Appendix. )

S~INC THE HENI OF A SELWER FOR VERTICAL AND ANGULAR Cum. A vertical cut is made in the shaper by setting the head on zero and arranging the apron so that the tool will clear the work on the return stroke, always having the tool feeding down. On the shaper, the down feed is used for vertical cuts such as finishing the sides of tongues and grooves, squaring shoulders, squaring ends, and cutting key- ways.

Except in the case of cutting-05 or a similar opera- tion, or where the surface to be machined is not much over l/4 inch deep or high, it is necessary to swivel the apron when using the down feed. When the top of the apron is moved in a direction away from the surface of the cut itself, the tool block and the tool will hinge in a direction up and away from the work during the return stroke.

Figure 19 shows the apron swiveled for a vertical

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cut, and the axis of the hinge pin is in line on ab. The direction in which the tool block will raise on the return stroke is in a plnn~~ shown as xy which is at right angles to CID. If this I&me is tipped away as shown in Fig. 19, the tool will raise in a direction away from the surfwe cm1 and will not run. If the plane were vertical, then the tool would rub along the surface down at s on the return stroke.

.4n angular cut is made b>- swivelio~ the head of the shaper and arranging the apron so that the tool will clear the work on the retorn stroke. Down feed is also u5ed for angular cats such as those for fairly wide beveled edges and for making dovetails. This

FiCmr I!,

movement is also true in angular or beveled cuts as well as vertical cuts (Fig. 20).

The general setup for nn nngular cut, with the head of the machine swiveled and the apron also set over, will sometimes appear wrong. Visualizing the angular cut as a vertical cllt and setting the apron accordingly will clarify the setup. For all ver- tical and angular cuts, the top of the apron must be set in R direction away from the surface of the cut to be taken.

Although the construction of the shaper does per- mit considerable down feed of the head, it is not good practice to use the head of the machine with the slide run down much below the swivel plate because it is not so strong and rigid in this position as when backed up by the ram. Sometimes this pro- cedure may be advisable or necessary, but in no other case should it be used for a finishing cut.

When the head of the machine is set over for an angular cut, and the machinist feeds the tool slide down too far, it is likely- to be brought up against the colunu~ as the ram slides back into position. Therefore, it is necessary when setting up to have the slide of the machine high enough at the start to make either a vertical or nn angular cut, and thus weakness or interference will never result during the actual cnt:iv~ operation.

Srr~mwc VmnchL ANo hCuLAH SmwxpIs. It is not always necessary to take an angular cut to pro- duce :m angrdar srlrface. An angular surface is one that is neither parallel nor sqt~~~ to any given base or to any other surface, and it may be machined in the shaIxr by sever.ll methods.


Figure 20

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First, the work can be supported on a tapered parallel, often called a taper cut rather than an angular cut. Second, a layout line may be scribed on the work to indicate the position of the surface to be planed; the work can be held in the vise with this line horizontal; and the regular power feed of the machine can be used for either a taper or an angle. Third, the work can be held in angular paral- lels. Fourth, the vise can be swiveled to the required angular setting. Fifth, when the machine is equipped with a universal table, this table can be used for making necessary adjustments for an angular cut. Sixth, the head of the shaper can be swiveled as shown in Fig. 20.

With the exception of a dcwncut on a piece that is held in a vise that has been swiveled to a given angle, ali of these si:; methods require only the regular horizontal cut. The sixth m&cd involves the nng~lar setting of the swivel head; this is called an angulaz cut. Figure 20 shows the setup of the shaper for the downcut for producing a vertical cut as shown at I, or an angular cut as shown at 2 or 3.

PLANWG FOUR SIDES OF A RECTANGULAR PIECE. The progressive steps for planing four sides of a rectangular piece in a shaper are shown in Fig. 21. Step 1 is to plane one side of the work, preferably one of the larger surfaces. Using this surface as a seat against the solid jaw of the vise, the adjacent side or edge, step 2, should be planed. If the vise jaw on the shaper is square and smooth, and if the surface that has been finished first is clean, is free of burrs. and is properly seated against the solid jaw of the vise, the second surface planed will be square with the first step or surface.

1 4


Figure 21


Figure 22

To make certain that the surface first planed is properly seated against the jaw of the vise, use a rod or a strip between the movable jaw of the vise and the work (2, Fig. 21). This will eliminate any tendency for the work to change its position owing to any giue there might be in the movable jaw. Place the second finished surface down, marked 2, on the bottom of the vise (3, Fig. 21), or if necessary on parallels. Place the first surface against the solid vise jaw (as in the second step) with the rod or strip between the movable jaw and the work, and tighten the vise. Tap the work down in a vise with a babbitt hammer so that it is properly seated on the bottom of the vise and the planed surface marked 3. If the jaw of the vise is square and the cutting tool is sharp, and if the surfaces of the finished work are clean, the two edges just planed should he parallel and square with the first side planed.

Now, place the first planed surface down on suit- able parallels (I in step 4, Fig. 21). Clamp the work between the jaws of the vise without the rod or the strip. With the babbitt hammer tap the work until it is properly seated. If the vise is true, and if the work has been seated on both parallels so that neither of the parallels can be moved, then the fourth surface will be parallel with the first surface and square with the other two sides of the work.

Seat the work on two parallels rather than on a single one because it is much easier to judge in this way whether the work is properly seated. At times it may be necessary to measure the piece that

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is being planed with either a micrometer or caliper, and this can be done more readily if there is a space between the two parallels. or between one parallel and the jaw of the vise.

Uslxc * P.wEa SHIM. It is sometimes necessary to have one or more adjacent surfaces planed square with a piece of work that has had one side previously planed. For this reason the work must he properly set up. There will be cases where the work is not square in the vise; in such instances, the adjacent surface, when planed, will not be square with the surface that has already been planed. This may happen when the solid jaw of the vise is out of sgunre. When the work is tightened against the fault); surface, it will be as much out of square as the vise jaw itself.

The necessary operations entailed when the solid vise jaw is not square and true have been previously clrccribed. However, in man;; instances these “pera- tions are not always practical or possible. In such cues, shim the work in the vise itself rather than shim the vise jaw (Fig. 22).

Unless the Z~ottorn side of the work is absolutely square with the side against the solid jaw. both of the parallels placed under the work will not be tight. No amount of hammering will seat the work on both parallels when the work itself is out of square, or when it is being held out of square, but a few light taps with the babbitt hammer will seat the work on both of the parallels when all conditions are correct.

SQVAIUNC THE 7;~~s OF mu WORK. Two methods are used for planing the ends of work square. Shorter pieces can be planed square by taking the cut hori- zontally across, and longer pieces by cutting ver- tically downward. A short piece of work is set either no the bottom of the vise or on suitable parallels; a finished edge or side is set perpendicular by using a machinist’s square.

Hold the square down hard on the parallel with the piece of work hard against the blade of the square, and tighten the vise of the machine lightly. Check the setting by tapping the work one way or the other, if necessary, before tightening it securely in the vise. If this has been properly done, and if the vise jaws are clean and square, vhen the end is planed it should be square with the surfaces that have already been planed. Then seat the work on the finished end, tapping it carefully again with a b&bitt hammer, and iinish the opposite end to the required length.

If the work happens to be too long for the ends

to be finished in this manner, the work should be set lengthwise in the vise with one end projecting in such position that it can be finished by taking a vertical cut. Use parallels to raise the work substan- tially flush with the tops of the jaws of the vise, allowing it to project from the end only a very short distance. After the vise has been tightened securely, the tool slide should be run well up toward the top, the apron swiveled, and the tool adjusted for the cut. Since the tool has to project a little distance from the tool post in order to take the cut to the bottom of the piece without any interference, a feed somewhat lighter than for horizontal planing is recommended.

Extreme care most be taken not to break out the corners at the end of the cut if the work that is being planed is made of cast metal. When working with cast iron or cast metal, an excellent finish can be obtained by using a side tool. About % in. of the cutting edge of this side tool should be ground straight and set vertically. Take a very light chip with a half turn of the down feed screw of the ma- chine for feed.


Modern shapers are equipped with a pressure oil- ing system similar to an automobile’s (Fig. 23). A gauge shows normal operating pressure when the

Figure 23. Oilrung dingrann

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&it& is cangaged; and a filter is used to keep the oil &3n. The oil dmdd be ii high-grade, nonfoaming nrRchiw oil; viscosity- .7L, “0 secolads and 100 degrees 6;‘. once 3 year. all tfie oil shdd be l-t-moved, and the hpk~ sbdd lw r&led with fresh oil.

&.fuw starting uhr SlKq’“‘. &c fdlol~-ing Sky” simdti be taken: (See Figs. 24 aud 25.)

1. Fill tmnsnrissioru rcser~:oir untii oil OVe&WS into return: basin, (Fig. 23).

2. EObricate motor aeccrding to motor manufnc- turer‘s reco”melldstiorns.

,a. - .4&r f&ng tbt !%mrrnissiorr rerervnir, open the ;oluntn door and fill the r&x12 basin and main reservoir :, Fig. Z;l. Fill until ail shops in sight window in base.

i. Clean and oil &Iiag surfaces of too!hc;ld. 6. ctean wrfaces of tabie suppo~f.


I”. Fill nil hole at rear of ram and two oil holes near ram adjustment shaft.

13. Qii mm adjusting screw th-ough opening in ram.

11. ~,il speed Aange lever bearings. 15. oil crank cluteb.


I?. Oil sbouId not be allowed to fall bel.ow sight gauge wbe~ shaper is stopped.

Figure 24. Lubrication +nts

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36267485 Metalworking Handbook - [PDF Document] (367)

In the plzner, the work moves back and fOl%h be- rmlh a rei?eionary tad. En &e shaper: Fhe tool ln""eS back and forth &we stationary work. The tad is fed to the work for each so~zessive cut in the ptaaer. IX the shaper, the ~0rk is fed eo ehe td ezepe for vertical feeding.

me single-pint cumng FOOI wed in a planer pro- duces an accwaee swface th is beer adapted to the s~craptng 0peraFisn e&m-z a maed surface. In heavy p%d~lceion I;ike parts of semm engines, locomoeives, printing p”e3S”S, IaFhe cmiagzs, and botroms of headsloc~ks and t&eocks, ehe ptanrr is indispensable. h typical madern &mer is shmm in Fig. 1.

&ion of Q Plaez

The various pants of a phaner are sHow5 in Fig. 2. They are as follows:

~hhe planer and carries the saddle slide toolhead as- sembty. It provides guides for the saddle transverse travel and n mounting for the transverse feed screw and gear.

A pair of Ixwl gears are on each housing and connected by a cross shaft so that each pair has the same movement. They form the gear for the raising or the lowering of the cross rail.

Figure 1. Modem High-swd planer.

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36267485 Metalworking Handbook - [PDF Document] (369)


Figure 3

!*.I,%! r<~trl’,\ g:“w ;~lt:tdred to abe feed screw of the iii,tuliiw The fxd scrc*\v to which the teed screw si’iir is ;rita&ed is turned. by the motion of the pawl.

?he fcec! u~~~I~~~~~~~I~~ ~~~f~~~~, is a disk having iin oscillating motion through a small xc. It carries a trankpin witl! an adjustable arm by means of the f-d screw. The crankpin is connected to the rack by a rod. The rack movement controlling the amount of feed may be varied by turning the feed screw.

By clamping the stroke dogs in such a position that they come in contact with tbc reverse lever at desired points on the machine, the amount of table movement of table stroke can be regulated.

by means of the rewrse lewr, the table can be stopped and reversed at the end of each stroke. It is actuated by the stroke dogs.

The power for driving a planer is applied to the &ice .s/raff by means of either belt pulleys or an electric motor, depending on the type of machine that is used.

The fnhle clriw mechanism is obtained by various methods such as rack and spur gears, spiral rack, and worm and crank. in the case of belt and pulley drive it consists of one open and one cross belt, each of which is belted to a loose pulley, which has a belt shifter to shift to a pulley that is keyed to the drive pinion shaft.

The tlrice pinion is the first gear of the reduction by transmission. The tangential speed of the belt most be reduced to obtain the relatively slow speed of the table because of the resistance encountered by the cutting tool. The first intermediate gear (Fig. 3 j is the first stage reduction gear; the second inter- mediate gear is the second stage reduction gear; and the bull wheel is the final gear between the

drive pinion and the rack. These gears are needed to obtain the necesmry large speed reduction be- tween the belt and the table.

A belt runs at a high velocity, usually 1,000 feet per minute, whereas the table must travel at a much slower speed, especially during the forward or cutting stroke of the tool, which is only 25 to 50 feet per minute. Therefore, big speed reduction is necessary.

Drive Methods

There are two methods of electric motor drive on planers, those with direct, and those with counter- shaft transmissions. In the direct method, the motor is connected directly or through gearing with the reduction gears of the planer. In the countershaft drive, the motor can either be placed on the bous- ing and connected directly to the countershaft, or it can be placed on the floor and connected to the machine by a belt. Note that all the essential parts in Fig. 2 are identical, that the modem planer shown in Fig. 4 has two toolbeads. In specially designed heavy-duty planers, features such as special trips, levers, and safety stops are provided.

Tools and Accessories

Planer tools and accessories are classified as gen- eral utility tools and special tools. Where a great many duplicate pieces are to be machined in the pkmer, it is necessary and practical to design and make a jig or fixture on which a specific job can be quickly set up, correctly aligned, adeqwtely sup ported, and properly clamped to the worktable. This tool is usually designed to bold one or more pieces,

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36267485 Metalworking Handbook - [PDF Document] (371)

Figure 8

Fiye 9

Figwr 10


The T-iwad bolt is simple to use and can be placed quicklv in position by dropping the head length- wise in the slot and turning it to the right. This hoit is used when it is necessary to clamp on the inside of -i casting which &en&e would have to be lifted eve: the bolt.

The tapped T-head is used when it is necessary to clamp inside a casting; the stud of the bolt can be removed and the bead pushed along the slot under the casting to the position that is desired on the machine. Studs of various lengths can be used as needed; thus requiring a small number of tapped T-heads.

CLAMPS. In machine shops where the only clamps av~ ‘lable are plain, flat bars with a bolt hole in the center, or perhaps two or three holes to allow the bolt to be placed in different positions, this type of clamp always requires blocking up at the end away from the work. The blocking should be of approximateiy the same thickness as the work so that the clamp will be flat and bear evenly on both work and block. A few simple clamps are shown in Figs. 7, 8, 9, and 10. The plain hairpin clamp (Fig. 8) is very common and can be used in many places. The clamp shown in Fig. 9 is useful for reaching into holes or recesses in castings, as shown. It is sometimes advisable to drill holes so as to leave the top clear. A plain, forged clamp is shown in Fig. 10. The bent-end clamp (Fig. 7) saves block- ing up at the back end and is very convenient. By using clamps with the end A of varying lengths, work of different thicknesses can be clamped easily and quickly.

When clamping work, the strap or clamp should be as nearly level as possible, and the bolt must be as near the work as it can be placed. Figure 11 shows several applications of clamps and shows the advantages of keeping the straps level. Figure 11 also shows different applications of plain and bent clamps.

The use of pxdlel strips on the planer table at times makes it easier to strap the work, for these parallels give good bearing points beneath the clamps and at the same time hold the work level. This may make it necessary to use some sort of an angle plate for an end stop because the parallels raise the work from the table. A cross piece held by stops jn the table may serve the same purpose, but some sort of stop must be provided to take the thrust of the tool.

There are clamps and blocks available (~wmmonly known as “CAD” clamps and blocks) that include a variety of clamps, step blocks, packing blocks, wedges, and cast-hardened nuts which increase tht~ life of bolts on which they are used. The T-slot forged nut is also useful, for it can be used with any bolt, although T-beaded bolts also have their place in setting up work on the planer table. Applica-

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Figure 12. Holding four pieces at once.

Table I

Figure 13. Use of clamps and step blocks

Figure 14. Step blocks keep the clamps level.

Figure 15 Work clamped at flanged base and on each side.

tions of these blocks and clamps are shown in Figs. 12 to 17’. NO detailed expianations of the blocks or clamps or the way in which they are used are neces- sary. Note that the bo:t is always placed as near the work end of the clamp as possible.

CLAMPING BLOCKS. The use of a step block in clamping is shown in Fig. 18. The block under the outer end of the clamp is a piece of metal of the required dimensions. If considerable height is re- quired, and if metal of the proper size is not avail- able, pieces of hardwood can be substituted.

The blocks and bolts shown in Fig. 19a will handle a large variety of work. The blocks A are planed

Tab/e I Figure 16. Unusual use of block combinations.

Figure 17. Blocks and steps keep clamps level at all points.


Figure 18

4 I 2 5


Figure 19a

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Figure 19b Figure 21. Finishing tool for cast-iron castings.

Figure 20. Double tool with forged bits.

to hook under the T-slot with the faces all the same distance from it. Blocks 6 are the same, except that they each ‘nave a setscrew as shown. Bolts C are made in a variety of lengths and have special nuts that fit in the T-slots. Stops D are round pieces of soft steel with the ends tomed to fit rhe holes in the planer table. They will be found useful in heights of two to six inches, but should rarely be made longer than this. These also have setscrews. The short stops are used to reinforce the long oees by bearing against the block laid between them.

SHMS. For fine adjustments or to give added support, shims or thin pieces of material may be placed between the work and the table of 5re ma- chine, and between any two pieces or parts of pieces. Shims are made of thin pieces of metal, wood, or even paper. Heavier pieces used in the same manner as shims are cal!ed packing blocks.

JACKS. Planer jacks of the type cb~wn in Fig. 19b are used for leveling the work or for supporting pro- jections under cutting pressure. The base shown at i has a diameter of 11/ inches and a range from Z’/,

Figure 22. Round too! for T slots,

Figure 23. Adjustable tool for T slots.

Figure 24. Finishing tool for cast iron.

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to 3,yY inches. With the two extension bases shown at 2 and 3 (provided by the manufacturer), the rangc~ is extended to 61,~; inches. The base shown at 3 is supplied when such n shape is required. Thr: pointed swcw slrown at 4 is iurnisbed in place of the scow with the swivel top at 1 for use in srlch setups as ia n cornc’r of tile work. When a jack or n base is required for work that is fairly high with a small seating surface, additional braces are used to counteract the tbendency of the work to tip under the cutting pwssure. A piece of pipe of the required !ength may bc used between the jack shown at 1, i“is. 19. and the base sbo~vn at 3, thus giving an ailjust:ible brace to the work.

<A-l-uxc TCOLS. The cutting tools that are used in 111:iner wori; we simil;ir to those used in the shaper, iwept tht thy are lqer. There are a number of slx~c:i;llizc4 cuttirig PI& mnnrlfxtured for specific ~~~~rp~~~s. 7’11~ ~10111~1~~ tools s!~own in Fig. 20 are spe- c,ial cttttcl-s that will Landle n large variety of work. I~i:~,l-c 21 shows a double-roughing tool with one tool locate-d behind the other. Forged tool bits of the* O.K.-type are used, their size depending largely on the work.

Spwiaily designed tools used for n variety of work wc slrown in Figs. 22, 23, end 24.

Where 3 number of T-s!ots must be planed, use the round tool (Fig. 22), or the adjustable tool (Fig, 23) The round tool can bc turned slight!y as it wears at the used point. The adjustable tool is manufnc-

Figure 25. Finishing to01 for steel.

Figure 26. Tml for finishing V’S, Figure 27

Figure 28. Tool fur plsning tongues.

Figure 29. Double taol holder.

tured with n screw for locking the size after the adjustment has been made; it can plane a shallower slot than the round tool.

Figures 22 and 25 show two types of finishing tools; one is used on cast iron, and the other on steel; both give n shearing cut leaving a smooth finished surface.

SPECIAL Cam~c TOOLS AND TOOL HOLDERS. Figures 26 to 30 show a number of special tools and tool holders. Figure 26 shows a cutter used for finish- ing the V-ways of a lathe or similar machine. The front edge of this cutter is in line with the bottom of the tool shank and prevents digging into the work. The tool shown in Fig. 27 is set at a negative angle to give a scraping cut.

Concave and convex radius tools are shown in Fig. 30; one is a solid cutter, and the other has a rcmovablc cutter. The convex tool with the round, coarse comer is made with a control pin or pivot so that it can be turned to present a new cutting edge without making a compicte haif tom. Where the radius approaches 180 degrees, the design shown in Fig. 30 is the simplest to make.

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4 D

Figure 30. Etadins tool. Figure 31. Now a tool springs into the cut and out of it

‘igum 32. Special right- and left- hand elling, 01 undercutting, tools.

Figure 33. Special slotting tool.

Figure 34. Other types of undercutting tool.

Figure ~5. Details of constntction of undercutting tool. Figure 36. Supporting overhanging tools,

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372 ?L.ANERS

Tools used for planing slots of tongues are shown in Figs. L?S and 29, and both use inserted cutters that are h&i at an an$e SC that the width of the tongue or the slot cm be mnintnined at the required size. Movin:: these cutters toward the front of ihe tool w!ll bring the cutting edges togher in the tooi for the tonjiur. and wiil move them apart in the other tool. The tapered pIus (Fig. 29) behind the cutters moves both cutters out hn equal amount.

The Whaien pIaner tool &own in Fig. 30 has an anron. a tool black. and a turret movement that aiion-s the tool to Ii turned to any angk required in the end of the shank. This makes it possible to smt in mv position. across the surface, down the ides. or to do ri$t-hand or Ieft-band undercutting. I?w t~urretbexi of this cotter is controlled by the tnit :ri tlw war. and there is no dragging on the r~~ttsrn strokt~. it is used in planing slots in the side c 11~ ~WH!C whew tbe sidetwnd of the machine cannot 116, wtd. .4 spring tool is used where the tool digs ini0 the v.wk owing to tbe softness of the material or stmtks or spots of hard metal. The primaiy object of the sprint tool is to hare the cutting edge away from the work rather than digging into it (Fig. 31). Thr tool at the left, which has the cutting edge ahead oi the center. will dig into the ;vork. The clapper box pin n is the block; but the spring of the tool would pivot at tbe point marked b; the arc of movement of the point is shown in both cases at A72 and BC. The spring tool at the right has the alttin: edge behind tbe clapper box pii: a, and xvii1 spa-ing away from the work.

SPI:~:I.AL Soon-rxc TOOLS. Forged tool bits held rigidly in suitable holders ax used for the planing of slots in tabies and similar work. The forged tool bit is heveled at the back end to fit the sloping recess in the bolder opening and is hz!d in place hy a headless setscrew. Tbe tool bit is supported directly back of the cutting edge, and the holder is made of h’gh-carbon steel. These tools are readily reset after grinding without disturbing the position of the tool shank in the tool block.

SFECI~IL TOOLS FOR UXDERCUT~XG. lindercutting, or “eliing,” with a planer tool is a job where the tmdency to spring makes it necessary to use a feed of 0.01CJ to 0.012 inch ax1 a cutting speed in cast iron of apprnximateiy 33 feet per minute. Increase of either the feed or the speed usually results in a bmkrw tool. The tool shown in Fig. 32 is used for ondercutting. \I:hen this tool is r~sed, the feed can hr doubled with safety. The tool holders are large mrl bff. whereas the supporting end is very deep in the direction of the thrust. The tools are forged O.K. tool bits bcld rigidly in place with the headless

setscrews (Fig. 33). The tool holder is of high- carbon steel, and the bits have serrations on the back by which they can be positioned in the holder so that the depth of cut remains the same.

Other types of undercutting tools are shown in Fig. 34, and their construction is shown in Fig. 35. The holder for this tool has a shank passing through the lower end of the heavy steel body, and the tool block can rock sufficiently to relieve the cutting point on the return stroke (Fig. 35). The tool holder has a large tapered shank which fits into the enlarged portion of the square shank and a straight thread for a round nut and locknut. The bar A is 2% inches square and 16?<< inches overall in length, with the tool opening at 1% inches square. The rocking tool holder (B, Fig. 34) has a substantial bearing in a semicircular seat, and during the cut, the planing tool bears solidly against the shoulder as shown at C. This is aided by the spring plugger (P, Fig. 35) that bears against the inner face of the hook strap (D, Fig. 34). This hook strap also holds the tool against the thrust of the cut. On the return stroke, the spring permits the tooi to rock back in its seat far enough to relieve the cutting edge.

NECESSAHY SUPPORTS FOR OVERI~~NGING Toois. When cutting metal, the cutting tool must be sup- ported as rigidly as possible. for there are times when t!w nature of planer work makes it necessary to use very long tools in ordr- to reach the part that is being planed (Fig. 36).

I\frLTwLE PL~XER TOOLS. When held in proper shanks_ the forged tool bits of the O.K. design give cxcellcnt satisfaction even on very trying work.

hnothcr tandem or multiple planer tool with forged tool bits held in place by specially designed wedges md hollow-head setscrews is shown in Fig. 37. This tool bolder carries seven small forged tool bits set to do its share of the work.

Figure 37. Mulliplc tool with sewn O.K. tool bits used 10r planing vs.

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,.I, :,,:I ;: ,, .,,,,: ,,.,. li iI:< ,,>,:I i/f!., c .: :I i ~:, ,,,, ~’

I,$:>/, ,l/ !I,,>! liM!,~, /,I, l;,,,c, ,/ll!i

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Extension Nut

Figure 41. Tool bolder and special strap for heavy wo:k.

Figure 43. Cutter for tool holder show in Figure 42.

tive bodies must be planed. One of the special planer tools for heavy work is shown installed in Fig. 40. De- tails of both tool holder and strap are shown in Fig. 41. The radius on the underside of the tool holder fits the tool block. The tool Ets against shoulders behind and at one side and is held in position by the special bolt and nut shown above the clamp (Fig. 41) The tool itself has a countersunk hole with a half-rormd keyway into which the special self-locking bolthead fits. This bo:t draws the cutter solidly against the holder hy means of the long, special nut with the hex- head shown with the bolt which reaches down through the tool shank. The head of the bolt can be seen above the strap in the right-hand head (Fig. 40). The main dimensions of the tool holder are given to suggest proportions for similar tools for other work.

Figure 42. Holder with dovetailed

Figure 44. Another tool for dovetail-bnrked tools that is supported under the clapper block.

The special strap at the right of Fig. 41 holds the tool from both sides against side movement due to the thrust of the cut. It is also recessed at the side for a side tool for special work, this tool being held by a one-inch setscrew at the side. When no side

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tool is used, it bears directly against the lower end of the tool holder. Another type of tool holder (Fig. 42) was designed for what is known as “short-base planing.” It provides a dovetailed support for the cutter against the thrust of the cut as weli as the same type of bolt as before, but it has no spe- cial nut. A cutter for this holder is shown in Fig. 43. Figure 43 shows how the dovetail fits into th:: holder and how the cutter is held by the same type of bolt. Figure 44 shows another type of tool. A third design of tool holder is shown in Fig. 45, in which the thrust of the cut is taken by a ~recess in- stead of a dovetail. The main dimensions are shown. Figure 46 shows a cutter that fits into the recess and is held by side clamps which grip the sides of the

Figure 45. Tool holder with side clamp for tools.

Figure 46. Tool for holder shown in Figure 45.

Figure 47. Clamps and bolts for holding cutter by dovetailed edges.

Figure 48. Tool holder for plate planing.

cutter by the dovetails. The clamps (Fig. 47) shown at the left as well as special-angle, or taper, washers may be used when necessary. Care should be taken to have the dovetails at the proper angle to insure solid clamping action. Figure 48 shows another tool holder designed for use in plate planing. This tool holder also uses a cutter with dovetailed sides, but it clamps it in a different manner. The clamp and tool are shown in detail in Figure 49. The clamp fits on the left side of the tool holder, completing the dove- tail. The cross tongue at the upper end of the clamp iits into s corresponding recess in the tool holder so that the 15$&degree taper of the dovetail on the tool is held firmly by a cross bolt through both clamps and the tool holder itself.

LEVELING THE WORK. Leveling the work is the setting up of the rough casting that is to be ma- chined. The casting must be supported at the proper

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Figure 49. Tool and clamp for Figure 48.

points by blocks or shims so that the work will not buckle or spring under the clamping pressure. The work should be leveled so as to average the corners for height, bearing in mind the necessity for later planing on the other side of the wol~k. It may be necessary to shim the work under two corners, or at times even under all four corners. No matter what clamping device is used, it may be necessary to place shims under the points where the clamping devices are applied because the tremendous screw pressure of bolts and nuts will sometimes spring a h