machinists handbook wartime supplement

Citation preview

TBH £72

rtime Data Supplement TO THE

American Machinists' Handbook 1

BY

FRED H. COLVXN AND

FRANK A. STANLEY

McGRAW.H1LL BOOK COMPANY, NEW YORK AND LONDON

1nc.

TBH £72

rtime Data Supplement TO THE

American Machinists' Handbook 1

BY

FRED H. COLVXN AND

FRANK A. STANLEY

McGRAW.H1LL BOOK COMPANY, NEW YORK AND LONDON

1nc.

*

7 -

Wartime Data Supplement TO THE

American Machinists' Handbook

\ BOOKS by

F. H. Colvin and F. A. Stanley Colvin and Stanley

AMERICAN MACHINISTS'

HANDBOOK TURNING AND BORING PRACTICE DRILLING AND SURFACING

PRACTICE GRINDING PRACTICE GEAR CUTTING PRACTICE RUNNING A MACHINE SHOP Colvin and Haas

JIGS AND FIXTURES

Colvin

AIRCRAFT HANDBOOK RUNNING AN ENGINE LATHE RUNNING A MILLING MACHINE GAGES AND THEIR USE IN

INSPECTION PLANING, SHAPING, AND SLOTTING

Stanley

PUNCHES AND DIES

Wartime Data Supplement TO THE

American Machinists' Handbook BY

FRED H. COLVIN

Editor Emeritus of American Machinist;

Author of "American Machinists, Handbook"; Fellow, American Society of Mechanical Engineers;] Member, Franklin Institute

AND

FRANK A. STANLEY

Consulting Engineer; Editor of Western Machinery and Steel World; Formerly Associate Editor of American Machinist; Author of "American Machinists' Handbook," "Punches and Diet," etc.

McGRAW-HILL BOOK COMPANY, Inc. NEW YORK AND LONDON 1944

WART1ME

DATA SUPPLEMENT

TO THE AMER1CAN

MACH1N1STS' HANDBOOK

Copyright,

1944,

McGraw-Hill Book PR1NTED

1N

All

by the

Company,

THE UN1TED STATES

Inc.

OF AMER1CA

rights reserved. This book, or

parts thereof, may not be reproduced in any form without permission of the

publishers.

Ill

THE MAPLE PRESS COMPANY,

YORK, PA.

'ocr^ TI)VA 570809 Preface The war effort has brought many changes both in material sub stitutions and in shop practices. This supplement shows changes that have been found advisable to secure increased production in various lines of work and includes such data as have been found helpful in the many and varied industries that are engaged in the production of war material.

The Authors.

February, 1944.

1

r

V

Contents

i

Preface

Section

I. Materials

Amola steel— Ampco metal — Kirksite— Magnesium and aluminum alloys— Meehanite and its heat-treatment — Quenching and drawing— Plastics — Plastics for dies— Catalin — Plexiglas — National Emergency (N.E.) Steels — Recommended substitute steels for materials contain ing nickel, chromium, and vanadium — Properties given to steel by alloying elements — Aluminum — Carbon — Chromium — Cobalt — Columbium — Lead — Lithium — Manganese — Molybdenum — Nickel — Nitrogen — Phos

phorus — Silicon — Sulphur — Tantalum — Tellurium — Tungsten — Uranium — Vanadium — Zirconium — Scrap ratio in metal production — Machining stainless steel.

II.

Screw Threads Acme threads — Gages for Acme threads —Translating thread standards

— Stub threads — 29-degree

stub threads

— 60-degree stub threads — Modified square threads — American National Standard gas-cylinder threads — Gascylinder valve-outlet threads — Hose connections for welding and cutting torches — American National rolled threads for screw shells of electric sockets and lamp bases — Form of thread — Thread series —The Aero screw thread system — Recommended practice for tapping— Recommended proportions of Aero- thread assembly.

III. Drilling

Deep-hole drilling — Drilling rifle barrels with carbide tools — Gun-barrel reamers and broaches— Portable boring-bar feeds and speeds — Gun-barrel broaches — Diamond-core drill fittings— Silver solders — Character istics of silver solders — Using silver solder — Heating; — Soldering — Soldering stainless steel— Drills for tapped holes — Recommended sizes — Hole circle layouts.

IV. Cutting Tools

tools — High-speed precision boring — Rake on cutting tools — Positive rake for soft metals — Negative Carbide

vii

viii

Section

CONTENTS

rake — Standard milling cutters — Face-milling cutter mountings — Carbide-tipped face mills — Mounting the cutter on the spindle nose — Causes and elimination of chatter — Broaches — Turret-lathe tools — Cutting angles for turret-lathe tools — Using carbides on older machine tools — Cutting speeds — Checking old machines — Cool ants for carbide tools — Small end mills.

V. Grinding-Wheel Markings Grinding Wheel Manufacturers Association

standard

—

Page

90

General objective — Sequence of markings — Marking — Abrasive cutting — Abrasive saws or cutting-off wheels — Grinding wheels— Care of grinding wheels — Grinding work speeds — Wheels for thread grinding.

VI. Gearing

Bevel gears — Angle of worm threads and helical gear teeth — Terminology — Hourglass worms — Cone gear tol erances — Gears — Gear-tooth clearances — Gear measure ment by wires — Allowance for backlash — Elliptoid gear teeth — Flame-hardening of gear teeth.

VII. Forging, Forming, Punching, craft Work

and Welding in

Air

Low-cost dies— Continental dies— Magnetic dies — The Guerin forming process — Square forming of metal stampings — Allowances — The pad form die — U bends — Soft-metal punches and dies — Cutting liquids — Forging aluminum alloys —Time for changing die sets — Alu minum materials formed by drop hammers— Workhardening — Aluminum forging temperatures — Welding —Tube welding for maximum strength — Atomic hydro of kerf in gen welding — Heliarc welding —Width flame cutting —-Tumbling work — Recent Practice — Dry

VIII.

96

112

tumbling.

Inspection

Lathe tolerances — Gages — Tolerances gages — Hydraulic

systems on machine oils — Recommendations.

of

gages — Glass

120

tools —Testing

IX. Metal-cutting

Saws 139 Hack and band saws — Power hack-saw blades — Flexibleback metal band saws— Hand hack-saw blades — High speed band saws— Friction disks and hot saws — Circular and band saws for plastics — Machinists' files.

Index

153

WARTIME DATA SUPPLEMENT SECTION

I

MATERIALS

Amola Steel. — Amola steels were developed by the late C. Harold Wills for the Chrysler Corporation to duplicate the physical prop erties of chrome-vanadium steels at a lower cost, using balanced The S.A.E. proportions of molybdenum, manganese, and silicon.

Table

1.

— Drill

Speed

for

Ampco

Grades

Metals of Different Finishing

Roughing Ampco Grade

Tool Material

Speed, in

Feet per

Minute

12 12

16 16

18

18

20

20 21 21 22 22

Cobalt steel Tungsten carbide Cobalt Tungsten carbide Cobalt Tungsten carbide Cobalt Tungsten carbide Cobalt Tungsten carbide Cobalt Tungsten carbide

Feed, in Inches

200

?J

175

32

175

32

100

A

100

64

75

1

1

1

i

1

64

Speed,

in

Feet per

Minute 300 500 250 400 250 400 250 350 200 300 200

Feed, in Inches

JL

64 X 64 1

Wt 1

64

64 1

64 1

64

300

In the proper proportions 4000 series is part of this development. these steels include properties that permit their use for cold heading and forgings, spring steel, ball and roller-bearing steel, tool steels

They were for shear blades, cold chisels, axes, and razor blades. first used commercially in 1933. Ampco Metal. — Ampco metal is a bronze alloy consisting of It is hard particles held in a softer matrix to give wear resistance. surfaces, wearing and bushings is used for centrifugally cast and

AMERICAN MACHINISTS' HANDBOOK Grade 22 is very hard to gears, worm wheels, cams, and rollers. machine. Angles for turning tools, drills, and taps are shown in Fig. 1. For milling follow standard steel practice as to speeds and feeds. Slow deep cuts to get under Teeth of cutters should be radial. the skin are best for roughing. Cutting speeds and feeds are given

in Table

1.

For harder Softer grades, 12, 16, and 18, can use standard taps. Brills grades grind off the lead edges to make the edge radial. for all grades should be ground a little off center to give added clearance, as shown in Fig. 1, as well as suggested point angle. Grind off

t overhang 1

Grind off oil roke

1°

rough for finish

Wot more than 'K'"nose radius

Slightly

center v^off ' End ^> rW0

Top View

Side View

View

Fig.

I

10° for

Turning Tool 1.

it

it

is

A

f

^

is

is

is

a

For grinding use resin-bonded silicon carbide wheels. Use a 60-grain wheel for finishing. 30-grain wheel for rough work and Kirksite. — Kirksite a metal with about 94 per cent of very pure It zinc, the remainder being aluminum, copper, and magnesium. It widely used in lighter than lead and melts at about 7i7°F. airplane plants for forming dies for sheet-aluminum parts. Magnesium and Aluminum Alloys. — Magnesium alloys are about two-thirds the weight of aluminum and one-fourth that of inch per foot when large, inch when steel. Castings shrink be both in small. avoided Sharp corners should castings and in Thread lengths should be twice machining, such as in spot facing. the diameter for National Coarse pitches and three times for fine (S.A.E.) threads. Magnesium can usually be cut at the maximum speeds available on machine tools. Oil-type coolants should be used for high speed and fine chips on account of fire hazard. three parts kerosene good coolant and one part lard oil. If fire occurs, smother with an asbestos mat, powdered soapstone, or graphite, which should be kept in containers near machines. Do not use water, for spreads the fire. Do not let chips accumulate on man or machine.

WARTIME DATA SUPPLEMENT

3

Grinding is best done with medium-hard wheels with clay bond and 30 to 46 grain. For snagging use 20 grain. When grinding must be done dry use high-suction exhaust fans with a capacity of 80 to 100 cubic feet per second. Grindings should be precipi tated in water on account of fire hazard. Grinding wheels should

marked "For Magnesium Only." Punch and die clearance should be small, 0.0015 inch being recommended for small sizes. Concaving the punch 3 degrees On sheets thicker than 0.065 inch, gives a smoother sheared edge. heating the sheet to 500 to 6oo°F. gives a smoother edge. The contraction after cooling must be allowed for in the punch. Dies for forming magnesium are usually heated either by gas or by electricity. In either case the heat must be kept at a uniform be

temperature over the entire die surface. The die surface should be kept well lubricated. A good mixture is 20 per cent graphite in tallow. Parts may be cleaned with a solution of 8 per cent chromic acid, plus 5 per cent nitric acid. A dip of 3 to 5 minutes at room temperature is usually enough. A 15 per cent chromic solution at boiling temperature can also be used. These fumes should be drawn off by ventilation, for they harm nasal passages. A tank of pure aluminum is necessary. Thin magnesium sheets may be blanked and punched in the same way as other metals. When over 0.064 inch thick they may show a flaky fracture unless dies have very small clearance. Thicker sheets should be heated to 5oo°F., but the shrinkage must be allowed for in the punch and die. For bends of 90 degrees the sheets should be heated to 350 or For a radius 400°F. for a radius of four times the sheet thickness. of the to the thickness a of 6oo°F. is equal temperature sheet, necessary.

MEEHANITE AND ITS HEAT-TREATMENT

Meehanite is a processed cast iron produced under rigidly con Meehanite castings are made in a trolled metallurgical conditions. chain of foundries, under license to produce work from this metal. Castings have been used for the past 15 years in the construction of many types of machinery and industrial equipment with distinct advantages to the purchaser. Meehanite responds readily to heat-treatment and permits the achievement of high physical properties, accompanied by either hardness or machinability. Three of the different heat-treatments that may be applied successfully to Meehanite castings are: (1) annealing for stress relief; (2) quench and draw; (3) annealing for machinability, and also machinability in the as-cast condition. Stress relieving of Meehanite is carried out at temperatures ranging from 850 to iiso°F., depending upon the density of the iron. In this treatment, care must be taken to see that the casting is not overheated. Overheating causes a marked deterioration in the internal structure, with a resultant loss of strength. A casting heated at noo°F. for 1 hour per inch of section will Yet this have only a slight drop in tensile strength and hardness.

AMERICAN MACHINISTS' HANDBOOK

4

temperature will remove any stress present in the casting and accomplishes the same results as the old process known as "aging," which was the practice of exposing iron castings to weather tempera tures for a period of from 6 to 8 months. Quenching and Drawing. — This treatment consists of heating the Meehanite casting slowly to noo°F. and then transferring the When the casting casting to a furnace heated to 1575 to i6oo°F. blends with the furnace, it is held at this temperature for 20 minutes per inch of section and then quenched in oil or water, preferably oil. Withdraw it from the quenching tank while warm —about 300°F. — Draw temperatures depend upon the and temper immediately. or tensile Table 2 shows the results hardness strength required. of draws at different temperatures on castings having an original tensile strength of 52,000 pounds per square inch.

Table

2. —

Result of Draws at Different Temperatures on

Draw Temperature, °F.

570 750 goo 1000 1200 1300 1400

Meehanite Strength

72,000 78,000 75,000 73,000

60,000 52,000 47,000

Brinell Hardness Number

45° 43° 335 291

256 234 207

PLASTICS

Plastics for Dies. — Two classes of plastics are used in making forming dies. Thermoplastics may be softened at any time by applying heat. Thermosetting plastics take a permanent set

after their first heating. Catalin. — This is a cast phenolic resin that is noninflammable. It weighs 0.048 pound per cubic inch. It can be tumbled to remove tool marks and sharp edges. Its strength varies from 3,000 to 6,000 pounds per square inch. Turning. — A zero or negative cutting rake with 10- to 20-degree clearance should be used for Catalin. Set tool 1 or 2 degrees above center. A honed tool gives smoother cuts. Dust and shavings should be removed by a blower system. Cutting speed is about 600 feet per minute. Drilling. — Drills for Catalin should have a slight negative rake on the cutting edge and have large flutes for chip clearance. For self-tapping screws use drill one or two sizes smaller than screw. Threading. — For coarse threads use thread milling machine for best results.

WARTIME DATA SUPPLEMENT

5

Cutting Off. — Abrasive cutting-off disks should be from 6 to 20 A thickness of 0.040 to -fa inches and usual inches in diameter. wheel speeds are suggested. Sawing. — Use band saws with 14 to 18 teeth per inch at 1,200 to 1,500 feet per minute or more. Lucite. —Lucite is a methyl-methacrylate resin that is very clear and transparent. Drilling. — Standard drills can be used, but best results are obtained with drills having a flute angle of 17 degrees, a lip angle The drill of 70 degrees, and a lip clearance of from 4 to 8 degrees. Flat drills can be used for lands, or margins, should be polished. drilling thin sheets. Hollow-end mills are also good for thin stock. A good drill speed is about 1 20 feet per minute, with plenty of mild Feed should be decreased as the soap solution as a lubricant. hole gets deeper. threads are recommended Threading. — Strong coarse-pitch instead of sharp Vs. The tap can be run at about 75 per cent of the speed used on brass. Plexiglas. — Plexiglas is an acrylic synthetic resin that is clearly It is derived from coal, petroleum, and water. It transparent. should be stored in a moderately moist and ventilated place, below 1 2o°F., away from direct sun rays. Cutting tools should have no rake. Oil or water coolants are permissible but not necessary. Feeds should be constant; if they stop the material burns. For Sawing. — Use any fine-tooth saw good for wood or metal. thick material every fifth tooth should be ground to clear the material from the cut. Run saws 8,000 to 12,000 feet per minute with fairly slow feed. Routers can run from 10,000 to 20,000 r.p.m. Drilling. — Use regular drills but with very little lead on cutting Withdraw drill frequently. Use light feed pressure. edge. Tapping. — Back tap out often to clear chips. Heat to tem Forming. — Plexiglas is pliable at 220 to 3oo°F. perature from 15 to 20 minutes, then allow surface to cool for 1 or 2 minutes before forming. Cementing. — Use special cements recommended by makers.

NATIONAL EMERGENCY (N.E.) STEELS

Shortages, caused by the demand for war purposes, of the alloys used in steels that are normally used to secure certain desired characteristics have led to the substitution of different steels in places where they can be safely used. Some of these steels, known by different trade names, use no chromium, vanadium, tungsten, or manganese, and only a small portion of molybdenum. These are known as graphitic steels and have good wearing qualities when properly oil-hardened. Some of these steels machine very freely.

Recommended Substitute Steels for Materials Containing Nickel, Chromium, and Vanadium. — In view of the critical situation on the three alloys, namely, nickel, chromium, and vanadium, it is highly desirable that all specifications be revised as far as possible so as to eliminate these scarcer alloys in order that their consump

6

AMERICAN MACHINISTS' HANDBOOK Table

3.

— National Emergency Steels Carburizing Grades Recommendation

A-1320 A-2317 A-2515 A-3120 E-3310 A-4119 A-4120 A-4320 A-5120 A-0120

1

Recommendation

A-4027

8024

A-4027

8024

None

None

A-4027

8024

None

None

A-4027 A-4027

8024 8024 8124 8024 8024

None

A-4027 A-4027

Semi-Thorough-Hardening Grades A-1330 A-2330 A-3130 A-4130 A-5130

S.A.E. 6130

A-4037

8233

A-4037

8233

A-4037 A-4037 A-4037 A-4037

Thorough-Hardening

8233 8233 8233 8233

Grades

(1) Sizes up to 3-inch round, inclusive, or equivalent (2) Sizes over 3-inch round, or equivalent A-1340 A-2335 A-2340

S.A.E. 2345 S.A.E. 2350

A-3045 A-3135 A-3140 A-3141

A-4047 (1) A-4063 (2) 8339 8447 8442 8447 8447 8547 8547 8442 8447 8339 8442 8442 8447 8447 8547

(0 (2) (1)

(2) (1) (2)

d)(a)

(1) (2) (1) (2)

(1)

(2) (1) (2)

8245 8447

None

None None None None None None

A-4068 (1) None (2)

None None None None None None

2

WARTIME DATA SUPPLEMENT Table

3.

— National Emergency Steels. — Continued Recommendation

A-3145 A-3150 A-3240

S.A.E. 3250 A-4137

A-4142 A-4145 A-4150 A-4340 A-4640 A-4645 A-4650 A-5045

S.A.E. 5140 A-5145 A-5150

S.A.E. 6140 A-6145 A-6150 A-9260

*

7

8447 o547 8547 8442 8447 8547 8339 8442 8442 8447 8447 8547 8547

(i)

WW

None

(l)(2)

(2)

(l)

A-4063 (1)

(i)

A-4068 (1)*

(l)

A-4068 (1)*

(2)

(2)

(2), (1X2)

(1) (2) (1) (2)

(1)

None (2)

A-4063 (1) A-4068 (2) 8339 8442 8442 8447 8447 8547 8339 8442 8442 8447 8447 8547

Recommendation

None None None None

(1) (2)

None

8339 8447 8447 8547 8547

i

(1) (2) (1) (2) (1) (2)

(0

(2) (1) (2) (1) (2) A-4068 (1) None (2)

2

None (2)

None (2)

None (2) A-4068 (1)* None (2) None None

None None None None

None

8339 (1) 8442 (2) A-4063 (1) A-4068 (2) A-4068 (1)

None

A-4068 (1)

None

(2)

A-4063 (1)* A-4068 (2) A-4068 (1)*

None A-4068 (1)* None (2) None

First recommendation for small tools.

tion may be kept to a minimum except where such alloys are more drastically required in the execution of orders for defense materials The American Iron and Steel Institute suggests alternate grades for the A.I.S.I. steels containing nickel, chromium, and vanadium Three alternates are included, namely, carbon-molybdenum of th«

8

AMERICAN MACHINISTS' HANDBOOK

(designated as 80, 81, 82, 83, 40 series, manganese-molybdenum 84, and 85 series), and nickel-chromium-molybdenum (designated The last grade is not applicable to as 86, 87, 88, and 89 series). orders without suitable priority, and so it will not be considered

in our recommendations.

Since subsequent decisions by the W.P.B. may change these views, the following alternates may be of a temporary nature. Although the A.I.S.I. has considered size in its recommendations, it was the consensus that we grade Thorough-Hardening steels for sizes up to 3-inch round, inclusive, and above 3-inch round or This is not necessary for carburizing and semiequivalent. Thorough-Hardening grades. These recommendations are based solely on metallurgical con siderations and are classified as first and second choice. Customers have the prerogative of specifying either grade. Where no recom mendations are made, it is believed that no suitable substitute is available.

PROPERTIES GIVEN TO STEEL BY ALLOYING ELEMENTS

Application of elements to iron to produce steels of varying qualities is strikingly similar to the application of drugs in medicine. Each element has separate and often powerful effects, with fre quently other effects in combination with additional elements. Like drugs, they may be beneficial in tiny quantities, but ruinous in great quantities unless neutralized or checked by supplemental

elements. An understanding of the chief characteristics given to steel by the elements is an aid to a better selection and use of steels, espe cially in tool use. Aluminum. — Deoxidizer. Restricts grain growth by forming Forms hard nitrides when heated dispersed nitrides and oxides. in contact with nitrogen, making extremely hard steel. Small amounts increase strength, but large amounts embrittle steel. From 2 to 5 per cent gives heat resistance and oxidation resistance. Carbon. — Hardener, by forming FesC under heat-treatment. Increases strength rapidly up to saturation point of 0.85 per cent, above which the steel becomes increasingly brittle unless there are other elements besides iron to take up the carbon. Forms hard carbides with iron, chromium, vanadium, increasing strength and wear resistance. Even slightest additions decrease the ductility. Gives very deep hardening Chromium. — Forms hard carbides. and great wear resistance. Small amounts toughen steel, increas Decreases machinability. ing strength and impact resistance. Decreases hardening range unless balanced with nickel. Retains Gives hardness at more elevated temperatures than iron carbide. slight red hardness. Cobalt. — Adds red hardness. Retains hard carbides at high ;emperatures, but tends to decarburize steel in heat-treatment. Increases hardness and tenacity, but considerable amounts decrease mpact resistance. Increases residual magnetism and coercive nagnetic force of steel for magnets.

L

WARTIME DATA SUPPLEMENT

9

Columbium. — Used to minimize intergranular corrosion in stainless steels. Has carbide-forming properties increasing strength and hardness, but not used generally for the purpose. Softening effect shortens time of annealing of high-chromium steels. Lead. — Forms minute strings and finely divided particles. Minute quantities give free machining without imparting the weak ening effect of sulphur. Lithium. — Combines easily with oxygen, hydrogen, sulphur, to form low-melting-point compounds which pass off as gases. Power ful deoxidizer and degasifier. Lithium treatment increases elastic limit of carbon steels. Increases fluidity of stainless steels to produce dense castings with high yield point. Manganese. — Deoxidizer and desulphurizer. Even minute Raises amounts increase hardness, wear resistance, and strength. solubility of the carbon. Lowers critical point and widens harden ing range, thus permitting a less drastic treatment in oil. Air hardening begins at about 1.5 per cent. Makes steel austenitic at about 12 per cent. High-manganese steel work hardens and is Small amounts Increases coefficient of expansion. nonmagnetic. increase depth of hardening and speed of hardening. Decreases Intermediate amounts tendency to distort under heat-treatment. produce brittleness unless other elements are present. Molybdenum. — Adds red hardness. Increases strength and impact resistance at high temperatures, but hardens and embrittles Retards grain growth. Gives deep harden at low temperatures. ing and widens hardening range. Increases creep resistance and Goes into resistance to deformation at moderate temperatures. solid solution, but when other elements are present forms hard carbides. In aluminum steels small amounts reduce temper Increases brittleness. Increases machinability of carbon steels. resistance of stainless steels at high temperature. corrosion Nickel. — Increases hardness, strength, ductility, and impact resistance. Narrows hardening range, but lowers critical point, Refines structure. reducing danger of warpage and cracking. Decreases machinability. Makes chro Retards grain growth. Balances the intensive deep-hardening mium steels austenitic. effect of chromium. Large amounts give resistance to oxidation at high temperatures. Hardens slightly and reduces Nitrogen. — Normally undesirable. Small amounts refine grain and increase strength of ductility. Forms hard nitrides with aluminum and, high-chromium steels. into balanced aluminum-bearing steels, introduced externally inhibits grain growth at high temperatures. Small amounts increase Phosphorus. — Promotes cold-shortness. Slight strength slightly and increase resistance to corrosion. amounts decrease tendency of steel sheets to stick together. out of Silicon. — Deoxidizer. Graphitizer. Throws carbon solution. Small amounts increase impact resistance, and up to 1.75 per cent increases elastic limit, but needs assistance of other Medium carbide-forming elements. Strengthens low-alloy steels. amounts increase magnetic permeability and decrease hysteresis

io

AMERICAN MACHINISTS' HANDBOOK

loss. Forms hard iron silicides, and large amounts give great hard wear resistance, and acid resistance, but cause brittleness. ness,

Has wide range of utility if used with expert technique, especially in alloy steels. Sulphur. — Forms soft and weak sulphides which weaken the steel Minute quantities advantageous to and promote hot-shortness. aid machinability. Tantalum. — Used in some special steels to give increased resist

ance to scaling at high temperatures. Tellurium. — Small amounts form sulphide which aids machining without making the steel hot short. Increases strength Titanium. — Deoxidizes and denitrogenizes. and hardness. Fixes carbon in inert particles. Minimizes intergranular corrosion in high-chromium steels. Tungsten. — Adds red hardness and stability of the hard carbides at high heats. Widens hardening range, and gives deep hardening. Small quantities produce Increases strength and wear resistance. Pro fine grain structure, but large quantities embrittle the steel. duces both a hard carbide and an iron tungstide. Large qualities, to produce full red hardness, must be supplemented by other Forms hard abrasive-resistant particles carbide-forming elements. in high-carbon steels. Adds acid resistance and corrosion resist ance. Gives increased residual magnetism and greater coercive . force in steel for magnets. . Uranium. —Increases elastic limit and strength of steels. Is deoxidizer and denitrogenizer. Has carbide-forming powerful Because of expense used only in some tool steels. qualities. Vanadium. —Powerful deoxidizer. Toughens and strengthens steels. Forms hard carbides. Refines the grain. Widens hard ening range. Retains hardness at higher temperatures than carbon steel. Reduces grain growth. Increases fatigue resistance and shock resistance. Forms double carbides with chromium, giving hard "keen-edge" quality to steel. Zirconium. — Powerful deoxidizer and desulphurizer. Steels can be made without manganese by use of zirconium. Carries off Makes uniformity of grain and produces ductility and nitrogen. shock resistance. Small amounts of residual zirconium form zirconium sulphide which aids machinability and rolling. Reduces aging fatigue in steel.

SCRAP RATIO IN METAL PRODUCTION

The part scrap plays in production is not generally realized. Steel production Figures for 1941 show the importance of scrap. for that year of 82,500,000 net tons of ingots required the use of An additional 17,000,000 tons of 44,600,000 net tons of scrap. iron and steel scrap was consumed by iron foundries and blast furnaces in making pig iron and other iron products. Thus a total of about 61,000,000 tons, or about half of the raw material required to make steel and iron products for the year, was iron and steel scrap. Of this total 27,000,000 tons (or 44 per cent) was "pur

WARTIME DATA SUPPLEMENT

11

chased" scrap produced outside the steel industry itself and col lected from general public sources. Table 4 shows roughly the importance of scrap in 1941 to the The alumi total production of other critical metals and rubber. num figure includes scrap recovered within the producing plant.

Table

4.

— Importance of Scrap

Total Scrap Total 1 94 1 in 1941 New New Supply, Supply, in Tons in Tons

Material

Antimony Lead

lead)

(including

antimonial

Tin

Zinc Rubber

416,000 47,600 2,117,500 1,090,019 101,850 178,528

923,300

1,441,000

W.P.B. Report, July

94,000 21,600

360,000 213,674

Ratio of Scrap to Total,

Per Cent

23

46 17 20

H.550

11

65,400 310,000

7 21

20,160

11

13, 1942.

MACHINING STAINLESS STEEL

Since stainless steel is used in much war material its peculiarities should be understood. The general practice recommended by W. B. Brooks, formerly with the Carnegie-Illinois Steel Company, is summed up in the following: "Use liberal cutting rake and clear ance. Use sulphur and sulphur chlorine cutting fluids liberally. Use first-quality high-speed tools. Support the tools rigidly. Keep the tools sharp and smooth; hone after grinding. Use a generous feed and cut below the work-hardened surface left by the preceding cut. Use rigid equipment with plenty of power for Use cutting speeds 20 to 50 per cent lower continuous cutting. than for machine steels."

SECTION

II

SCREW THREADS ACME THREADS for Acme Threads. — Both "go"

and "not go" gages, Gages the extreme product limits, are necessary for the representing proper inspection of Acme screw threads.

— Tolerances

foe "Go" and "Not Gages, Acme Threads

From

To

From

To

6

7

8

9

0 .

0 0 0 0 0 . .

0 . 0

ooooo

ooooo ooooo ooooo ooooo

0008

0

.

0

ooooo ooooo ooooo ooooo

ooooo

o.ooos

0.0010 0.0010

ooooo

ooooo ooooo ooooo ooooo ooooo ooooo ooooo ooooo

0.0010 0.0010 0. 0010 0.0010 0.0010

.

0006

.

0008

0.0007

ooooo

0

.

0.0010 0.0010

0003

0.0004 0004 0 . ooos

0006

0.0007

0

5 5 5 5 5

0

0003 0004 . 0004 . 0005 0005 .

ooooo ooooo ooooo ooooo

10 10 10 10 10

Inches Inches Inches Inches

ooooo

±

ooooo ooooo ooooo ooooo

Min.

oo oo oo oo

. ooos 0007 0008 0.0005

±

Minor

oo

.

Diameter

ooooo

0 0 0 . .

Diameter

oo oo oo oo

0005 0.0005 0006 ooos . oooo . ooos .

Tolerance on

Major

oo

0005

Deg.

5 5 5 5 5

. .

0

.

0

0 0 0 0 0

.

ooos

o.ooos o.ooos 0.0005 0.0005

o.ooos 0.0005

0 0

ooooo ooooo OQOOO ooooo

ooooo oo

oo oo oo oo

1

1f

0

0

ooooo

ooooo ooooo ooooo ooooo

0 0004

3 2

1*

0003 0003 . 0003 . 0004 . 0004 .

3* 2*

0.0002 . 0005 0.0002 0.0005 0. 0002 0.0005 0.0002 o.ooos . 0003 ooos .

ooooo ooooo ooooo ooooo

4 5 6 7 8

9

ooooo

14 12 10

±

0

16

Inches

Go" Thread

Tolerance on

5

5 5

Inches Inches

4

0 0 0 0 0

3

0

2

Tolerance on Half Angle of Thread

0 0 0

To

in

Lead

.

1

From

ance

0 0

Inch

Toler

0 0 0 0

Tolerance on Thread Thick Threads ness at Basic per Pitch Line

0 0

1.

0

Table

0.0010 0.0010

0.0010 0.0010 0.0010 0.0010 0.0010 0. 0010

0.0010

is

1

Table given here for the purpose of establishing definite limits for gages used in the inspection of Acme threads, rather than for the purpose of specifying the gages required for the various inspection operations. The dimensions of gages should be in accordance with the principles (1) that the "go" gage should check 12

WARTIME DATA SUPPLEMENT

13

simultaneously as many elements as possible and a "not go" gage can effectively check but one element; and (2), that permissible variations in the gages be within the extreme product limits. 1. Tolerances on Lead. — The tolerances on lead given in Table 1 are specified as an allowable variation between any two threads not farther apart than 12 inches.

plfiaj/ir rhickness-*\

of thread 'A Fig.

1.

=

£ 2.

— Acme

thread dimensions.

Tolerances on Angle of Thread. — The tolerances on angle of thread, as specified in Table 1 for the various pitches, are toler This ensures that the ances on one-half of the included angle. will be bisector of the included angle perpendicular to the axis of the thread within proper limits. The equivalent deviation from the true thread form caused by such irregularities as convex or concave sides of thread, or slight projections on the thread form, should not exceed the tolerances permitted on angle of thread. 2.

AMERICAN MACHINISTS' HANDBOOK TRANSLATING THREAD STANDARDS

American Standard ASA B1.3-1941 on Acme and other trans lating threads was designated as an American Standard in Sep tember, 1 94 1.

Table

2. — General-Purpose

Detail Dimensions

Acme Thread — Screws for Recommended Diameter

and Tolerances and Pitch Combinations (Dimensions in Inches)

Major

Pitch

Diameter

Pitch 5

Minor

Diameter

Diam eter

Diameter

Helix

Angle

Toler

Threads* per Inch

ance in

Max. (Basic)

D

Terms of Thread

Max.

Min.t (Basic) Min. E

Max-t Min.t Thick ness

Varia

tion

8800 0.0080

0.0088 3800 0.0096 4550 0.0103 4550 0. 01 X300

45 50 O.OX11

1 2 3

3967 4800 4800 4800

0.0057 0.0057 0.0065 0.0072

1 1

1407

1 1 1 1 1

0 0

0

0 0

50

3

0 0 0

1 1

8967

4 ,i 2 2 2 r

0523 2993 5463 7100 7070 7070

0. 0049

12

42 33

3

0200 0925 2175 4675 7175

2816 3441 3800

0 2275

33

5O 3

4 3 4 4 5 3 4 3 4 4

0300 1050 2300 4800 7300

1310 2280 3530 6000 8470

23

2 2 2

. 0034 4800 4737 5633 5550 0.0034 6883 0 6800 0.0041 7800 7700 0. 0041 9050 8950 0.0049

2 2 3 3 3

0

0 0 0 0 0

0 0 0 0 0

1744 0.0026

1 1 1 1 1

1 0 0

5495 6537 7757 8840 0060

1775

0.0026 2774 0.0026 3399 0.0026 3750 0.0026

4 .! 2 2 2 1

0833 3333 5833 7500 7500 7500

1 1 1 1 1

1500 2500 3750 6250 8750

2 2 2 2

2333 4833 7333 9750 9750 9750

2 2 2 2

2400 3625 4875 7375 9875

X 1 1 1 1

1 0

0 0

6187 5625 6667 7417 8667 0 7917 9900 9000 XX5O 0250

0 0

0

0 0

2187 0 2087 2668 2768 3333 3233 3958 0 3858 4500 4400

4

0 0 0 0 0

2469 3089 3708 4333 4950

4 i

0 0 0 0 0

0 0 0 1 0 1 1 1 1 1

2500 5000 7500 0000 0000 0000

l

2500 3750 5000 7500 0000

2 2

6250 7500 8750 0000 1250

4 3 2 a

0 0 X 1 0

25OO

3125 3750 4375 5000

2 1 1 1

2 2 2 3 3 3

4 4 4 4

5

5 5

6 6 8

14 12 12 10

s 4 .! 2 2 2

16

0 0 0 0 0

0ize

i ;.„

h \ 1

i} 1

i

2 1 1 ■ ; l

AA2\ s 4 3

Deg. Min.

33 10

39 19

48 26 55 43 21

19 26 55

is

is

§

is

X

is

t

*

is

arbitrary and intended for the The selection of threads per inch purpose of establishing a standard. These dimensions result in tolerances on major and minor diameters equal to o.osp. such as to result Maximum minor diameter of a screw of a given pitch in a flat at the root equal in inches to 0.3707£ — (0.52 X clearance) when at its maximum value. the pitch diameter of the screw The length of gage should be equal to the length of engagement which in this case one and one-half diameters.

This standard covers the design and dimensions of Acme and similar single screw threads intended primarily for translating screws. The designs included have been chosen with the dual

WARTIME DATA SUPPLEMENT

15

purpose of meeting varied needs of the users to the greatest possible extent and at the same time establishing a product capable of economical production. The diameters and pitches have been selected with a view to meeting the present needs with the fewest number of items in order to reduce to a minimum the inventory of The tolerances are such as to produce both tools and gages. complete interchangeability and maintain a high grade of product. Four series of translating screw threads are included in this standard — the general-purpose Acme, the 20-degree stub, the These screw thread 60-degree stub, and a modified square thread. series are intended to cover such applications as lathe dogs and clamps, track drills, steel bench vises, machine-tool vises, drill-press vises, lifting jacks, steel hand clamps, valve stems, cross-feed screws for lathes, letter-copy presses, and elevating screws on machine tools and other machines. The subject of Acme and kindred threads embraces a wide field, and it is not possible to combine in a single standard all the variables of all the uses. The following applications are recognized as common usages, but each has special features that prevent inclusion in a general-purpose standard: 1. Feed and lead screws where backlash or end shake are objec In such applications the nut is tapped first and then tionable. the screw is threaded to fit. The screw and nut so made are kept as a pair. 2. Long lead screws where sagging causes threads to seize. In such applications the major-diameter clearance is reduced so that bearing takes place at the major diameter before seizing can occur. 3. Assemblies where the thread must maintain some degree of In these applications a alignment as well as transmit motion. reduced major-diameter clearance is the most effective and eco nomical means of obtaining satisfactory assemblies. 4. There is a considerable demand in mechanical industries for threaded assemblies that provide faster advance per revolution and give greater wear surface. The threaded forms covered by this specification are used frequently, incorporating changes in details to meet particular requirements. It is recommended that no coarser thread for a given diameter than those listed be used but instead that a multiple thread giving the desired lead be Many applications in the valve industry are typical. adopted. Where it is necessary to use multiple threads, the form of single thread corresponding to "crests per inch" of the multiple thread should be used. In the Acme general-purpose thread the angle between thi , sides of the thread is 29 degrees. The threads are truncated top and bottom, give a basic depth and thickness of 0.50 of the pitch, and are symmetrical about a line perpendicular to the axis of the screw. This series should be used for all Acme thread applications except in special cases where design or operating considerations are such that the 20-degree stub, the 60-degree stub, or some other modified thread can be employed to better advantage. Basic dimensions of the Acme general-purpose thread re given i| Table

1

AMERICAN MACHINISTS' HANDBOOK

6

31, page 48,

"American Machinists' Handbook."

Detailed dimen pitches for diameters from

sions and tolerances for recommended to s in. are given in Tables 2 and 3.

J

Table

3.

— General-Purpose

Detail Dimensions

Acme Thread — Nuts for Recommended Diameter

and Tolerances and Pitch Combinations

(Dimensions in Inches)

Major

Size

1 1

A ' 1

i

Threads* per Inch

16

14 12 12 10

8 6

1

6

1i

5

X

'I 1

1}

1f

2

2\

2

a!

3

4 s

5

5

4 4 4

Max.

2600 0 3225 0 385O 0 4475 0 5200

0 2337 0 2918 0 3483 0 4108 0 4650

0

0 6450 0 580s 0 7700 0 6847 0 8950 l1 8127 0 0200 0 9201 X 145O 1 0490 1

1

1

1

2700 3950 5200 7700 0200

2

3 3 3

2700 5200 2 7700 3 0200 .1 0200 5 0200

2 2

2

2

Minor

Diameter

Min.

4

2

Pitch

Diam eter

1 1

1

1

1

1740 2770 4020 6500 9080

Min.

Diameter

Min. Max.t (Basic)

K

Pitch*

Diameter Tolerance in Terms of Thread Thickness

Variation

1906 2447 0 3383 0 2959 0 4008 0 3584 0 4550 0 4050

0 0 0 0 0

0 0 0 0

5675 6717 7967 9050 0300

5063 5917 0 7167 0 8100 0 9350

0 5000 0 5833 0 7083 0 8000 0 9250

0 0 0 0 0

1

1550 2550 3800 6300 8800

1

0500 1250 2500 5000

0 2237 0 0 2818 0

1

X

1

1

X

2 1213 2 2 3743 2 2 6273 2 2 8000 2

0 0

t

1

1

1

0600 1375 2625 5125 7625

1

i

1

1

1

0903 1 9334 1 3403 2 1834 2 5903 2 4334 2 7600 2 5250 2 3 8030 3 7600 3 5250 .J 4 8030 4 7600 4 5250 4

1875

241 1

2917 3542 4000

7 500

9167 1667

4167 5000 5000 5000

0 0026 0 0026 0 0026 0 0026 0 0026 0034 0034 0041 0041 0049

Helix

Angle Deg.

5

4

4

3

4 4 4

Min. 12

42 33

5O 3 3

3 4

33 50 3 33

0 0 0 0

0049 0057 0057 0065 0 0072

3 3 3

39

2

2

48 26

0 0080

2 2

55 43

0 0103 0 Oii1 0 Oii1

3

19 26

0 0088 0 0096

3

2

2

1

10

19

21

55

* The selection of threads per inch is arbitrary and is intended for the purpose of establishing a standard. t These dimensions result in tolerances on the minor diameter equal to 0.0s*. % The length of gage should be equal to the length of engagement, which in this case is one and one-half diameters.

STUB THREADS 29-Degree Stub Threads. — The angle between the sides of the

thread is 29 degrees as in the case of the general-purpose Acme thread; the threads are truncated top and bottom, but the basic The basic thread depth of thread is reduced to 0.30 of the pitch. thickness is one-half the pitch as before, and the threads are sym metrical about a line perpendicular to the axis of the screw. This produces a very strong thread section, and in addition a thread admirably suited to applications where space limitations or other Basic economic considerations make a shallow thread desirable. dimensions of the 20-degree stub thread are given in Table 4.

WARTIME DATA SUPPLEMENT

Fig.

Table

4.

2.

— 29-degree stub

— Basic Dimensions of

17

threads.

29-DEGREE

(Dimensions in Inches)

Stub Threads Width of Flat at

Threads per Inch

Pitch,

t

Depth of Thread (Basic), * = 0.3P

Total*

Depth of Thread

Thread Thickness (Basic), i = o.SP

Crest of Screw (Basic),

F

=

0.4224; 1

2

3

4

6

5

0.0188 0.0214

9

0.06250 0.07143 0.08333 0.10000 0.11111

0.0333

0 0 0 0 0

8

0. 12500

0.0375 0 .0429 0.0500 0.0600 0.0750

0 0 0 0 0

0.0857

0 0957 0 1 100

0 1429 0 1667

0 1600

0 2500

16 14 12 10

7 6 5

4

3*

3, 2I 2

0. 14286

0. 16667 0 . 20000 0. 25000

0.28571 o-33333

0 . 40000 0 . 50000

0.0250

0 . 0300

0. 1000 0. 1200 0. 1500

0238 0264

0300 0400 0433

047s

0529 0600

0700 0850

0 1300

0 0 0 0 0

0313 035 7 0417

0 0 0 0 0

0625 0714 0833 1000

0500 0556

1250

0 2000

* A clearance of at least o.oio inch is added to k coarser, and 0.005 inch on finer pitches, to produce interference with threads of mating part at minor recognized that there are conditions under which may be desirable.

Root

l

of

Screw, Fc = 0.4224; (0.52

Clear

X

ance) 7

0 0 0 0

0264

0 0 0 0 0

0528 0603

00551

0845 1056

0. 1004

0 0 0 0

1207 1408 1690 2112

0302 0352 0422 O 0469

0704

0.0238 0.0276 0.0326 0.0370 0.0417 0.0476

0.0652 0.0793

0.H55 0.1356 0.1638

0 . 2060

on threads of io-pitch and extra depth, thus avoiding or major diameters. It is a greater or less clearance

AMERICAN MACHINISTS' HANDBOOK

i8

6o-Degree Stub Threads. —The angle between the sides of the The threads are truncated top and bottom, thread is 60 degrees. have a basic depth of 0.433

01

the pitch, a basic thickness of one-

0.02 pv

NUT

,0.2165?

SCREW

Fig.

3.

— 60-degree

stub thread.

half the pitch, and are symmetrical about a line perpendicular to the axis of the screw. Basic dimensions of the 60-degree stub thread are given in Table 5.

Table

Threads per Inch

1

16 14 12

10 9 8 7

6 5

4

5.-

-Basic Dimensions of 6o-Degree Stub Threads (Dimensions

Pitch, P

Depth of Thread (Basic),

in Inches)

Total*

Depth of Thread, 0>

+

Thread Thickness (Basic),

f

=

o.s*

Width of Flat at Crest of Screw

Root of

0.250*

0.22TP

F

-

-

Screw

F.

0.433*

0.02*)

3

4

5

6

7

0.06250 0.07143 0.08333 0. 1 0000 0.

0.0271

0.0283 0.0324 0.0378 0.0453 0.0503

0.0313 0.0357 0.0417 0 . 0500 0.0556

0.0156 0.0179 0.0208 0.0250 0.0278

0.0142 0.0162 0.0189 0.0227 0.0252

0. 12500 0. 14286 0. 16667

0.0541 0.0619 0.0722 0.0866 0. 1083

0.0566 0 . 0647 0.0755

0.0625 0.0714 0.0833

0.1133

0. 1250

0.0313 0.0357 0.0417 0 . 0500 0.0625

0.0284 0.0324 0.0378 0.0454 0.0567

2

inn

0 . 20000

0. 25000

0 . 0309

0.0361

00433 0.0481

0 . 0906

0 . 1000

* A clearance of at least 0.02P is added to h to produce extra depth, thus avoiding interference with threads of mating part at minor or major diameters.

MODIFIED SQUARE THREADS

The angle between the sides of the thread is 10 degrees. The threads are truncated top and bottom, have a basic depth of 0.50

WARTIME DATA SUPPLEMENT

19

of the pitch, a basic thread thickness of 0.50 of the pitch, and are symmetrical about a line perpendicular to the axis of the screw. The angle of 10 degrees results in a thread that is the equivalent of a "square thread" insofar as all practical considerations are concerned and yet capable of economical production. This thread form is illustrated in Fig. 4. t

Clearance Tsee note)

NUT

allowance SCREW

Fig.

Clearance (seenole) 4.

— 10-degree

square thread.

Multiple-thread milling cutters and ground thread taps should not be specified for modified square threads of steep helix angle without consulting the cutting-tool manufacturer.

AMERICAN NATIONAL STANDARD GAS-CYLINDER THREADS

Gas-Cylinder Valve-Outlet Threads. — Standard sizes of threads valve outlets of various types are presented in Table 6. The purpose of these standards is to prevent cross con nections of equipment used with a given type of valve with another type where such connection may be dangerous or undesirable, as well as to promote interchangeability among threads of a given type of valve. Hose Connections for Welding and Cutting Torches. — Specifi cations covering hose connections for welding and cutting torches were formulated and adopted in 1925 by the International Acety lene Association, the Gas Products Association, and various manu facturers. Essentially the same specifications were adopted by the National Screw Thread Commission in 1926. Revised specifications for these connections were adopted by the International Acetylene Association, Mar. 9, 1939. These revised specifications were adopted by the Interdepartmental Screw Thread

for gas-cylinder

Committee and are presented below. Dimensions essential to the interchangeability of parts have been standardized. Other dimensions and details of design are optional, so that manufacturers may use their own judgment and follow their usual practice as much as possible. Four sizes of connections are specified, as illustrated in Table 7.

0nhydrous

threads

external except

for anhydrous

ammonia,

"-14

0P0

and

0PS

f

All

f"-i8

alL

are

(internal0 form

right-hand

1.031

0.8350

8200

0.8932

except

I.025

on

0.8290

0.8290

Max.

for

7780

7780

.9717

valves

0.

0.

0.7836

Min.

hydrogen,

0.9677

0.7740

0.7740

0.7786

0.8530

Pitch

0hreads

Diameter

0.8566

Outlet

Max.

eter

Diam

Minor

nitrogen,

0.7368

0.7424

0.8154

of

Min.

Thread

Length

and

1 11

helium.

are

ammonia

form

2 0PS

.

0.8350

8300

.

o.835"-i40S-3

9030

Min.

0

Dichlorodifluoromethane

i

chloride

o.003"-i40S-3

Valve

Major Diameter

Max.

0 0

.

o.83o"-i40S-2LH

00hes0

Cylinder

of Thread

Gas

in

3

helium

Designation

(Dimensions

Standard

4

or

Valve

0ational

0

Ethyl

Cylinder

American

6

nitrogen,

of

—

7

Hydrogen,

Type

0able

6.

0

WARTIME DATA SUPPLEMENT

21 0

» 0 N0 W0 10

M

to w

M0M0^0fO00 do do doo 00 +1

+1

H5

X

10

0 n 0

So

0

po

+1

«.

HS

0^0 m t- m io0i!0 0

iOCC

0 *-

00000000 I

+1

N

J=2

N

+1

I

I

0 0 0 0 0 0

OSS

f—CO

+1

I

1

+1

I

M 1

M I

M I

HS

3:

SIS

SK

r0*

Hto

1-3

0 10

po 10 10 10 •

00O00000 +1

+1

-«* O

„

+1

Hs

+1

h«

«*©

™|h

«|oo

h|n

n£

^

a*

O

C)

M

SlS

P,

Nro0

inM

0

CO

M

*0O f^O

vo

•*•

-i»

h«

h«

,H|W M

«(J

Ha

Hose

«IS

•0*

-w

HS

hS

"TrH

«l»

«*»

«5

O

Q

-

ig6

M

h«

o.

Radius

N

o.ogg

H«

M

For Class

«

+1

0.438

^|S

+1

0.280

|S

Flats

+1

across

Width

Radius

1$

M

«(•

Diameter

+1

L, K,

of

HS

oooooooooooo

0izes

J.

Length 0houlder

r3j*

ir)00c^0QO00000 N00-*00i«00000

of Hole

3

z

HS

^*

Hs

f-

4*

1

00

Length Over All

Q,

Length of Hole

S,

of Depth Full Thread

AMERICAN MACHINISTS' HANDBOOK

0hank

22

1!

WARTIME DATA SUPPLEMENT

23

Standard Dimensions. — 1. Screw threads to corresponding Class 3 of the American National fine-thread series are specified. Right-hand threads are specified for oxygen and left-hand threads for

fuel gas. 2. Angle and outside diameter of internal seat. 3. Radius and distance of radius center of external seat from shank shoulder. 4. Diameter of shank shoulder. 5. Diameter of hole in nut. 6. Large diameter of hose shank. 7. Fuel gas nuts to be designated by annular groove around nuts, cutting corners. Optional Features. — 1. Material of strength equal to or greater than that of free-turning high brass. 2. Diameter of hole through external fitting and gland. 3. Form of end of shank, except seating section as dimensioned. 4. Length of hose shank. 5. Type and number of serrations on hose shank. 6.

A

second shoulder equal to the large diameter of the largest

shank to extend through the hole in the nut for appearance, to be used or omitted for smaller diameter shanks. 7. Length and location of hexagon wrench section on nut.

AMERICAN NATIONAL ROLLED THREADS FOR SCREW SHELLS OF ELECTRIC SOCKETS AND LAMP BASES The

specifications given here for American National rolled threads for screw shells of electric sockets and lamp bases, with the exception of the more recently adopted intermediate size, were originally published in Bulletin 1474 of the American Society of Mechanical Engineers entitled Rolled Threads for Screw Shells of Electric Sockets and Lamp Bases, which was a report of the A.S.M.E. Committee on Standardization of Special Threads for Fixtures and Fittings.

Table

8. — American

National Rolled Threads for Base Screw Shells

Lamp-

(Dimensions in Inches) Threads per

Size

Inch

1

Miniature.

2

. .

Candelabra . . Intermediate. Medium

Pitch

3

14 10

9 7

4

0.07143

iiiii

0. 10000

0. 0. 14286 0. 25OOO

Depth of Thread

4

Major

Ra

dius

5

0. 020 0. 0210

0.025 0.0312 0.027 0.0353 0.033 0. 0470 0.050 0 . 0906

Diameter

Minor

Diameter

Max.

Min.

Max.

Min.

6

7

8

9

0.375 0.465 0.651 1.037

0.370 0.460 0.645

0.335 0.415 0.597 0.971 1-455

0.330 0.410 0.591 0.965 1.455

1. 555

1. 031 1. 545

AMERICAN MACHINISTS' HANDBOOK

24

Form of Thread. — The thread form is composed of two circular segments tangent to each other and of equal radii, as shown in Fig. 5Depth of

Socket Screw Shell

thread I

0 •& .8 .0 •§

Fig.

5.

I

E

6

.g 5

5

6

J

g e

•!*

B

— Thread for electric sockets.

8.

Thread Series. — The sizes for which standard dimensions and " tolerances have been adopted are designated as follows: Miniature, candelabra, intermediate, medium, and mogul." The threads per inch, radii of thread form, and diameter limits for these sizes of lamp-base screw shells, which are used on lamp bases, fuse plugs, attachment plugs, and similar devices, are given in Table The corresponding dimensions and limits for socket screw shells, which are used in electric sockets, receptacles, and similar devices, are given in Table 9.

THE AERO SCREW-THREAD SYSTEM

a

The Aero screw thread has been developed to meet problems of securing threaded parts in aluminum and magnesium to withstand the stresses imposed by studs and bolts in aircraft engines and similar installations without failure of the softer metals. The system uses closely wound bronze or steel coil spring insert that screws in the soft metal and receives the steel stud or bolt.

WARTIME DATA SUPPLEMENT Table

9.

25

— American National Rolled Threads for Socket Screw Shells (Dimensions in Inches)

Threads per

Size

Inch

1

Miniature

3

2

. . .

Candelabra. Intermediate.

.

Pitch

0.07143

14 10

iiiii

0 . 10000

0. 0. 14286 0. 25000

9 7

4

Depth

ol

Thread

4

Major

Diameter

Ra

dius

Minor

Diameter

Max.

Min.

Max.

Min.

6

7

8

9

5

0 . 020 0.0210 0.383s 0.025 0.0312 0.476 0.027 0.0353 0.664 0.033 0.0470 1 -053 O.O5O 0 . 0906 1.577

0.3775 0.3435 0.3375 0.470 0 . 426 0.420 0.657 0.610 0.603 1 .045 0.987 0.979 1.565 1.477 1.465

It involves the use of a special tap for threading the soft metal to receive the insert and a special form of thread on the bolt or The forms of these threads are shown in Figs. 6 and 7. stud. The thread that receives the insert approximates the standard T

Fig.

6.

— Aero

iiL

screw thread and capscrew.

American form. Details of the tapped holes and the bolts are The term V.A.T. refers to "V Aero-Thread." given in Table 10. The first section of Table 10 refers to the bolt or stud, which has a special rounded form of thread. The second section gives dimensions of the holes tapped in the soft metal and the last section gives dimensions of the tapped hole with the insert in place. This gives the number of the insert to be used and the root diameter of the thread formed by the insert. It will be noted that the root diameter of the insert is somewhat larger than the root diameter of the standard American nut, because of the difference in thread form. Tables 11 to 13 explain themselves. Details of the thread in the soft metal of the insert and the thread form of the bolt, are shown in Fig. 4. The data on the different dimensions are also given.

26

AMERICAN MACHINISTS' HANDBOOK /Maximum tap

Boss or Nut -

—

Pitch

/

jdia.-\

Minimum tap

liTS i/ dia.-\ p

I

^—Basic

major dia.

of inserfS

Thread form diarQ

Pitch

dial E

Basic screw dia- D Roof dia. of aero

Screw or Stud

Fig.

7.

thread lK

•Form of Aero screw thread.

Description Symbol Designation for external screw form used on screw, stud, Aeroor bolt, and for internal screw form produced by insert Thread assembled in tapped hole Aero-Thread size is specified by nominal screw size D and by number of threads per inch n. Designation of tapped hole V thread into which AeroV.A.T. Thread insert is assembled size D and threads per inch n of screw used in insert assem bled in tapped hole. Nominal screw size: major diameter of screw and minor diameter of tapped hole Pitch diameter of tapped hole

V.A.T. thread size is specified by screw

E

(1)

D + 0.4P

=

Root diameter of screw and root diameter of insert assembled in tapped hole (minor diameter of AeroThread)

K

(2)

=

D

l

o.6p =

l

E

p

Major diameter of insert assembled in tapped hole Major diameter of tap

Ii

(5)

T2

maximum

/j

=

1. 0405/o

D +

at tip =

1.104^

minimum (radius at tip r2 = D + 1. 122/,

:

(4)

S = D +

^flat

(3)

0.07 2p)

(6)

G

Diameter of thread form circle of Aero-Thread = 0.75^

D

E

WARTIME DATA SUPPLEMENT Number of threads per inch

27

Description

Symbol

n p

Thread pitch

#-5

(7)

j

Depth of engagement of insert in tapped hole

j=

(8)

0.525/o

Depth of thread engagement, insert in screw

*

(0)

=

h

°-3P

Use Class 3 fit for bolt and nut, capscrew, setscrew applica tions; Class 5 fit for all stud applications. The depth of thread of the V.A.T. tapped Aero-Thread form must provide a full tapped thread depth within the limits to be The Aero-Thread V.A.T. finishing tap and singlespecified. are designed to guide on the minor diameter to taps operation with the pitch diameter of the tapped concentricity its ensure thread.

Recommended Practice for Tapping. — In soft metals drill 0.000 to 0.015 inch undersize, in which case the minimum diameter of tap will machine the minor tapped thread diameter concentric with the pitch diameter of the tapped thread. In hard cutting or abrasive materials, it is recommended that the drilled hole be reamed 0.002 to 0.006 inch oversize, in which case the tap will guide on its minor thread diameter. Recommended Proportions of Aero-Thread Assembly. — The boss diameter B is in general the same as in the other screw systems, the relative dimensions depending on physical properties of the boss and noting screw materials as follows: 1.

Tapped hole

Boss Material

Magnesium alloy castings Aluminum allov forgings Aluminum allov castings Magnesium alloy castings

2.

Screw

Screw Material

Alloy steel Alloy steel Alloy steel Alloy steel Aluminum alloy Aluminum alloy Aluminum alloy

Ratio of Boss B to Screw Diameter D

1.6 to 2.0 2 .0

2.3 2.5 1 .

6

1.8 2.0

to 2 . 5 to 3 . 0 to 3.5 to 2 . 0 to 2.4 t0 2.6

AMERICAN MACHINISTS' HANDBOOK

28

It

is good practice to have a thread length

L

sufficient to ensure

that under excessive loading the screw will break at the root of the screw before the thread is stripped from the boss. The following are recommended thread engagement lengths in the boss for general screw and stud applications: Length of Thread Steel studs forgings

and

Material

screws in steel castings

and

Engagement L in Terms of Screw Diameter D

1.5D

Aluminum alloy screws in aluminum or mag nesium alloy bosses Steel screw or stud in light alloy materials — this

i .$D

standard generally used Steel screws or studs in light alloy castings when the screw is highly stressed and the boss material is expected to be weakened by high operating im temperatures, sponginess, or material perfections

Table

10.

2D

2. 5D

— Aero-Thread Standard Series Class (Dimensions in Inches)

3

or 3D

Medium Fit

Aero- Thread Screw Size

Threads per

Inch

A

Root Diameter

Basic

Tolerance

Max.

Min.

Max.

Min.

0.1875

+0.000

o. 1625

0. 1607

0.0336

0.0313

o . 2200

o. 2180

0.0400

0.0375

0 . 2792

0. 2769

0.0445

0.0417

+ 0.000 — 0.005 + 0.000

0.3375

0.3351

0 . 0499

o . 0469

0.3946

0.3919

0.0570

0.0536

+ 0.000 — 0.006 + 0.000

0.4500

0.4470

0.0665

0.0624

0.5125

0.509s

0 . 0665

0.0625

0.5650

0.5618

0.0794

0.0750

o. 2500

I

A

Major Diameter

18

0.3125

16

0.3750

14

0.4375 0 . 5000

0. 562s

—

0.003 + 0.000 — 0.004 + 0.000

—o. 004

—0 . 005

— 0 .

006 + 0 . 000 — o . 006

Thread Form

10

0.6230

10

0.687s

+ 0.000

0.6275

0.6243

0.0794

0.0750

9

0.7500

+ 0.000

0.6833

0.6796

0.0881

0.0833

— 0 006 — o . 006

WARTIME DATA SUPPLEMENT Table

29

10. — Aero-Thread

Standard Series Class Fit.-— Continued

3

Medium

(Dimensions in Inches)

V.A.T. Tapped Hole Threads

Size

Inch

Major Diameter Min.

Max.

o 0 1 o

24 20 18 16

1 7

14

i

12 12 10 10

o

I

H

\

9

0. 2343 0.3062

0. 2373

0 . 3098

0.3789

0 3749

0 . 4496

0.4452 0.5177

0. 5996

0.5936 0.6561 0.7372 0. 7997 0. 8746

0. 5228

0.6621 0.7444 0.8069 0.8826

Pitch Diameter Max. 0 . 2066

0. 2726 0.3377 0.4032

0 . 4697

0.5373 0.5998 0.6695 0.7320

0 . 7993

Min. 0. 2042 0. 2700 0.3347 0 . 4000

0.4661 0

5333

0.5958 0.6650 0. 7275 0. 7944

Minor Diameter

Tap Drill Size

Min.

Max. 0. 1917 0.3181 0.3813 0.4446

0. 1875 0. 2500 0.3125 0.3750 0.4375

0.5083 0.5708 0.6350 0.6975 0.7611

0 . sooo 0.5625 0.6250 0.6875 0. 7500

0. 2550

No.

11

i o i o i

o

f

0

1

V.A.T. Tapped Hole with Assembled Insert Size

Threads per

Inch

Major Diameter Basic

0

Tolerance

Root Diameter Max.

Min.

Insert

Number*

24

0

1875

+0

0042

0 1649

0

1625

220-30

20

0

2500

+0 0050

0 2226

0

2200

220-40

18

0 3125

+0 0056

0 2822

0

2792

220-50

16

0 375o

0 3407

0 3375

220-60

ft

14

0 4375

0 3982

0 3946

220-70

i

12

0 5000

0 4540

0 4500

220-80

12

0 5165

0

i

0 5625

5125

220-90

10

0 6250

0 569s

0

5650

220-100

H

10

0 6875

0 6320

0 6275

220-110

0 6882

0 6833

220-120

I

0 i

ft

i

9

0

7500

— 0 0000

— 0 0000

—0 +0 —0 +0 — 0

0000 0063 0000 0071 0000

+ 0 0083

— 0 0000 + 0 0083 — 0 0000 + 0 0100 — 0 0000 + 0 0100 — 0 0000 + 0 O111 — 0 0000

Note: For larger sizes use eight -thread series (Table 12). * See Table 12 for length of insert.

AMERICAN MACHINISTS' HANDBOOK

30 1.

Tapped Hole

Stud

2.

HE

Notes Basic major diameter or nominal size Boss diameter Thread length

D. B.

Table i1. — Aero-Thread

L.

Standard Series Class in Inches)

(Dimensions

Aero-Thread Threads per

Major Diameter

Inch

A

i A

Ma

ance

Fit

Stud

Screw

Root Diameter

Toler

Basic

5

Thread Form Diameter

Min.

Max.

Min.

0. 1875

+ 0. 000

0. 1677

o . 1665

0 . 0336

0.0313

0.2500

+0.000

0. 2255

0. 2242

o . 0400

0.0375

0. 2840

0.0445

0.0417

—o. 003 —

18

0.3125

I

16

0.3750

A

14

0.4375

0.004 + 0.000 0.2855 — 0.004| + 0.000 0.3445 — 0.005 + 0.000 0.4024

0. 5000

+ 0.000

0.4584

0.4564

o . 0665

0.0625

A

0.5625

+0.000

0. 5211

0.5191

0 . 0665

0.0625

I

0.6250

+ 0.000

0.5741

0.5719

0.0794

0.0750

o. 7500

+ 0. 000

O .

6926

0.6902

0.0881

0.0833

i

i

—0. 005

— 0 . 006 — 0 . 006

— o . 006

— o . 006

0469

0 . 3429

0 . 0499

o .

o . 4006

0.0570

0.0536

V.A.T. Tapped Hole Size

s A

i

Threads per

Inch

24 20 18 16

Major Diameter Max.

Min.

0.2373 0.3098 0.3789

0.2343 0.3062

0 . 4496

14

0. 5228

12 12 10

0

9

5996

0.6621 0.7444 0.8826

Pitch Diameter Max. 0 . 2066 0. 2726

0.4452 0.5177

0.3377 0.4032 0.4697

0 . 5936

0.5373

0 3749

0.6561 0.7372 0.8746

0 . 5998 0 . 6695 0 . 7993

Min.

Minor Diameter Max.

Min.

Tap

Drill Size

0 . 4000

0. 1917 0. 2550 0.3181 0.3813 0 . 4446

0.1875 No. 0. 2500 0.3125 0.3750 0.4375

0.5333 0.5958 0.6650 0.7944

0.5083 0.5708 0.6350 0.7611

0.5625 0.6250 0.7500

0. 2042 0. 2700 0.3347

0.4661

0 . 5000

11

i

't

WARTIME DATA SUPPLEMENT Table i1. — Aero-Thread Standard Series Class Continued

3* Stud Fit.-

5

V.A.T. Tapped Hole with Assembled Insert Threads per

Size

Inch

Major Diameter Basic

A

Insert Number

Root Diameter

Toler

Length

Min.

Max.

ance

See Note

24

0.187s

+ 0 0042

0

1649

0

1625

220-30

20

0. 2500

+ 0 0050

0

2226

0

2200

220-40

A

18

0.312s

0 2822

0

2792

220-50

1

16

0.3750

0 3407

0 3375

220-60

A

14

0.4375

0 3982

0 3946

220-70

)

12

+ 0 0083

0 4540

0 4500

220-80

A

0.5000

12

0.5625

+0 0083

0

5165

0

5125

220-90

1

10

0.6250

+0

0100

0 5695

0

5650

220-100

0.

l0

0000

0 6882

0 6833

220-120

i

9

1

750O

— 0

OOOO

—0 +0 —0 +0 —0 +0 — 0

0000 0056 0000 0063 0000 0071 0000

— 0 0000

l

0 0000

— 0 0000 +0 O111

Note: See Table 12 for length of insert. First three threads of stud to conform to Table

Table

10.

12. — Aero-Thread

Insert Standard Sizes To Designate Insert Material Use Symbol B for Phosphor Bronze or C for Stainless Steel after Insert Number (Dimensions in Inches)

Threads per Inch

A

i

t

34 20 18 16 14

Insert

Num ber

Free

L

Assembled Length of Insert

Diam eter

220-30 220-40 220-50 220-60 220-70

0.250 0.330 0.405 0.485 0.570

220-80 220-90 220-100 220-110 220-120

0.64s 0.730 0.810 0.900 0.990

l.$D

2.5O

3D

A

ii

ii

A

iA

li

yj +

A A

ft

i

+ + +

+

L L L L L

A + L A +L

H

ii

Note: Depth of tapped hole is generally length of insert.

Overall Depth of Hole

H +L

A

to

A

longer than assembled

AMERICAN MACHINISTS' HANDBOOK

32

Table

13.

— Aero-Thread Eight Thread Series Class

Fit

(Dimensions

Size

i 1

ii

Threads per

Inch

Basic

Root Diameter

Thread Form Diameter

Max.

Min.

Max.

Min.

Toler ance

Medium

in Inches)

Aero-Thread Screw Major Diameter

3

8

0 8750

+0

000

0 8000

0 7958

0 0990

0.0938

8

1

0000

+0

000

0 9250

0 9208

0 0990

0.0938

8

1

1250

8

1

2500

8

1

3750

8

1

8

— 0 006

— 0 006 + 0 000 — 0 007 + 0 000 —0 007

1

0500

X

0457

0 0990

0.0938

1

1750

X

1704

0 0990

0.0938

+0 000

1

3000

1

2953

0

0990

0.0938

5000

+0 000

1

4250

1

4201

0

0990

0.0938

1

6250

+0 000

1

5500

X

5449

0

0990

0.0938

8

1

7500

1

6750

1

6698

0 0990

0.0938

8

1

8750

1

8000

1

7945

0 0990

0 . 0938

2

8

2

000

X

9250

1

9194

0 0990

0.0938

2t

8

2

125

+0

2i

8

2

250

+0

2*

8

2 500

+0

2J

8

2 750

+0

3

8

3 000

+0

3i

8

3

250

+0

3}

8

3

500

+0

3i

8

3 750

+0

4

8

4 000

+0

4i

8

4 250

+0

41

8

4 500

+0

4i

8

4 750

5

8

5

000

5i

8

5

250

si

8

5

500

5}

8

5

750

+0

6

8

6 000

+0

1j

ii ii 1!

if u

—0 007

—0 007

—0 +0 —0 +0 —0

+0

—0

—0

—0

—0

—0 —0

—0

l0

—0 —0 —0

—0 +0 —0 +0 —0 +0 —0 +0 —0

—0 —0

007 000 007 000 008 000 007 000 007 000 008 000 008 000 008 000 008

000 008 000 008 000 008 000 008 000 009 000 009 000 009 009 009 000 009 009 009 000 009 000 009

2 0500 2

1750

2 0442

0

0990

0.0938

1689

0

0990

0 .

2

0938

2 4250

2 4185

0 0990

0.0938

2 6750

2 6681

0 0990

0.0938

2 9250

2 9180

0

0990

0 .

0938

3

1750

3

1680

0

0990

0.0938

3

4250

3 4179

0

0990

0.0938

3 6750

3 6679

0 0990

0.0938

3 9250

3 9178

0 0990

0 . 0938

4 1750

4 1677

0 0990

0 . 0938

4 4250

4 4177

0

0990

0.0938

4 6750

4 6676

0

0990

0.0938

4 9250

4 9176

0

0990

0.0938

5

0

0990

0.0938

5

X750

1675

5 4250

5 4174

0 0990

0.0938

5 6750

5 6673

0

0990

0.0938

5 9250

5 9173

0

0990

0.0938

WARTIME DATA SUPPLEMENT Table

13.

33

— Aero-Thread Eight Thread Series Class Fit. — Continued

3

Medium

V.A.T. Tapped Hole Size

Threads per

Inch

Major Diameter Max.

1 11

if 1*

ii

1}

if it

2

3t 2$ 2}

2|

3

3\ 3} 3l 4,

4i

*i 5

si 5}

6

0150 1400 2650 3000 5150

S 8 8 8 8

1

8 8 8 8 8

6400 7650 1 8900 2 0150

1

1

1

1 1

X

2

140

2 2 2 2

00

265 390 640 890 3 140

8 8

3 390 3 640

8 8 8

00

00 00

8

3 890

4

140

4 390

8 8 8 8 8

4 640 4 890 5 140 5 390 5 640

8 8

5 890 6 140

Min. 1

1

1

1

1

J

Pitch Diameter

0000 1250 2500 3750 5000

0 .9242 1 .0493

0

1

1 .

4251

6250 7500 8750 0000

X

1

.1746 .2999

125

2

5503 6756 8008 9261 0513

2 250 2 375 2 625 2 875

2

1765

1

1

2

2

3

Min.

Max.

125

1

1

1

1

2938 4188

X

1

5438 6688 7938 9188 0438

1

1

1

1

1

2

1688

X

8875 0125

0

X

8750 0000

X

X

1375 262 s

3875

1

2500 3750

X

5125 6375

X

5000 6250 7500 8750 0000

1

1

1

7625

1

1

X

1250

8875 2 0125

2

2 2 2 2

1250 2500 2 5000 2 7500

1

X

i ii H ii ii

1

if i|

2

2i 2i 2i 2i

3

2938 5438 7938 4 0438 4 2938

262s 5T25 3 7625 4 0125 4 2625

2500 5000 3 7500 4 0000 4 2500

3i

3038 5 5539

4 5438 4 7938 5 0438 5 2938 5 5438

4 5125 A 762s 5 0125 5 2625 5 5125

4 5000 4 7500 5 0000 5 2500 5 5000

5 8040 6 0540

5 7938 6 0438

6

7625 0125

5 7500 6 0000

4 5536 4 8037 5 0537

5 875 6 125

0

Size

3 OOOO

4 625

5 125 5 375 5 625

9188 0438

1

Min.

2625 5125 7625 3 0125

3 3031 3 .5532

4 875

Max.

Tap Drill

1688 2938 2 5438 2 7938 3 0438

3020 2 5525 2 8030 3 0531 2

3 375 3 625 3 875 4 125

4 375

Minor Diameter

8033 4 0534 4 3035 3

5

2

2

3 3 3

1375

3 3

5

2

2

3 3

3t

3i

4

4l 4i

41 5

5T

5i 51 6

AMERICAN MACHINISTS' HANDBOOK

34

Table

Size

i 1

13.

— Aero-Thread Eight Thread Series Class

Fit. — Continued

Threads per

Inch

3

Medium

V.A.T. Tapped Hole with Assembled Insert

Major Diameter

Basic

Tolerance

Root Diameter Min.

Max.

Insert Number*

8

0.8750

+0

0125

0

8054

0 8000

220-140

S

1

OOOO

+0

0125

0 9305

0 9250

220-160

+0

0125

1

0558

1

0500

220-180

1

1811

1

1750

220-200

li il il

8

1

1250

8

1

2500

8

1

3750

1}

8

1

5000

1»

8

1

6250

8

1

H

8

2

— 0 0000

— 0 0000

— 0 0000 + 0 0125 — 0 0000

+0

0125

1

3063

1

3000

220-220

+0

0125

1

4315

1

4250

220-240

+0

0125

1

5568

1

5500

220-260

7500

+0

0125

1

6820

1

675O

220-280

1

8750

+0

0125

X

8073

1

8000

220-300

8

2

000

+0

0125

J

9325

1

9250

220-320

2t

8

2

12s

+0

0125

2 0577

2 0500

220-340

2j

8

2

250

+0

0125

2

1832

2

1750

220-360

2\

8

2

500

+0

0125

2

4337

2 4250

220-400

21

8

2

750

+0

0125

2

6842

2 6750

220-440

3

8

3

000

+0

0125

2 9343

2

925O

220-480

3i

8

3

250

+0

0125

3

1843

3

1750

220-520

3i

8

3 500

+0

0125

3 4344

3 4250

220-560

31

8

3

750

+0

0125

3 6845

3 6750

220-600

4

8

4 000

+0

0125

3 9346

3 9250

220-640

41

8

4

250

+0

0125

4 1847

4 1750

220-680

4i

8

4 500

+0

4 4348

4 4250

220-720

4i

8

4

750

4 6849

4 6750

220-760

5

8

5

000

4 9349

4 9250

220-800

5i

8

5

250

Si

8

5

500

si

0125 0000 0125 0000 0125 0000 +0 0125 + 0 0000 +0 0125 — 0 0000

8

5

750

6

8

6 000

li

* Length of insert:

i|,

2, 2},

— 0 0000

— 0 0000

— 0 0000 — 0 0000

— 0 0000 — 0 0000

— 0 0000

— 0 0000

— 0 0000

— 0 0000

— 0 0000

— 0 0000 — 0 0000 — 0 0000

— 0 0000

— 0 0000

—0 +0 —0 +0 —0

5

1850

5

1750

220-840

5

4351

5 4250

220-880

+0 0125

5

6852

5 6750

220-920

+0 0125

5 9352

5 9250

220-960

— 0 0000 —0

and

3

0000

basic diameter.

SECTION

III

DRILLING

DEEP-HOLE DRILLING The drilling of rifle barrels of various diameters for guns used in the war has given wide experience in deep-hole drilling. One such drill is shown in Fig. 1. This had cemented carbide drill tips that -0.078

A,

|

I

Fig.

1.

— Deep-hole drill.

Buttweld-btend special ftutes into straight flutes and polish " 3" speed

steely

*^?§^high '

Bushing

j^-^^

Provide chip breaker on cutting edge {Plug hole

f

fr,,.„

t Oil

holes

-4

r First of 4 reamers

^

3l€

'Back taper not to exceed 0.0005 "in this length

Fig.

^Bushing

Tools must stand 5001b.

coolant pressure

2. — Drill for larger hole.

As will were ground to the shape shown in the detail sketches. be seen, this is a single-lip drill, as is common in work of this kind. It is the first drill for a 20-mm. gun, the drill being 19 mm., or 35

36

AMERICAN MACHINISTS' HANDBOOK

The drill is guided through a suitable bushing and 0.760 inch. the chips are washed out through the V groove by coolant at 500 pounds pressure. The drilling speed was 1,040 r.p.m. or about 50 feet per minute. The feed was 0.001 inch per revolution. The barrel was afterl reamed in three passes to 19.96 mm. and finally honed to 20 mm. The drilling and reaming coolant was 80 per cent sulphurized oil and 20 per cent light mineral oil. Another type of drill for a larger hole, 1.81 inches, is seen in Fig. 2. This was a flat drill of high-speed steel for 12 inches, as shown, butt-welded to a special section of steel rod, as shown. The flutes of the shank were polished to make it easier for the chips to be forced out with the same pressure as before, 500 pounds.

f

DRILLING RIFLE BARRELS WITH CARBIDE TOOLS

Gun drills with carbide tips and carbide wear plates around the periphery of the drill will give exceptionally high production rates because of fast permissible feeds and long life between grinds. Such drills, designed and manufactured at the Poughkeepsie plant of International Business Machines, Inc., are, according to manu facturing engineer T. R. Skofteland, being used for drilling gun barrels and other gun parts made from steel up to 380 Brinell hard ness and have run as long as 20 hours between grinds. Compared with high-speed steel drills, feeds have in some cases been doubled.

The two carbide wear plates which back up the tip show negligible wear throughout the life of the drill, thereby maintaining its accu racy and producing smooth holes with minimum run-out. Standard drills of 0.293, °-300i °-33°, 0.697, °-733 and 0.781 inch in diameter have been made to date, using the production sequences illustrated for the 0.293-inch size, Fig. 3. A drill of entirely different design, but also employing the carbide tip and wear plates, is used for drilling a 1.150 inch air-cylinder hole in the The produc receiver body of a 20-millimeter automatic cannon. tion sequence and design of this latter drill are shown in a second drawing, Fig. 4. Seats for the carbide tip and wear plates are milled in the drills. Grade H-D Firthite is used for the cutting tip, while Grade T-16 Firthite is used for the wear plates. Both the tip and wear plates are brazed in the slots using Hand & Harmon's Easy-Flow No. 3 The conventional gun-drill grind is used on all sizes. It metal. is important that the cutting edges be honed to a mirror finish. The 0.293-inch drill shown is for drilling 30 caliber rifle barrels Although an average feed of 2 inches per minute 24 inches long. is used, 2 1 inches per minute has been maintained for long runs. In production, this drill has been used for 20 hours without grinding. Drilling is done in W. F. & John Barnes six-spindle vertical Each machine machines, the spindles running at 2,800 r.p.m. Based on an turns out one 30 caliber barrel every 2 to 3 minutes. average life of 20 hours between grinds, each drill is good for 70 to Comparable production has been 75 barrels before resharpening. attained with drills of other sizes.

WARTIME DATA SUPPLEMENT „i„,J

P»

I- Cut

-off,

.

3

y

6-

center,

grind aD.

Fit Grade

37

H-D Firthite

tip to drill body

£l*K*i" (

tip and wear

in place

Break sharp

—

1

—

30

r

—

I1

(

1_

Mill second wear strip slot A

W*mT " 4- Mill flute 65 oerocase i 0.002- 0.004"

9- Cut flush with insert and wear strip on right end

A-A

105°

|§ &

53 — 5-

sect1on

1«

45'*,*'

/

OAS

Section A-A

Mill seat for carbide tip insert

OPERATIONS

ON

10- Drill oil

hole-

Grind drill

THE

Fig.

0.293' 3.

GUN

DRILL

AMERICAN MACHINISTS' HANDBOOK

WARTIME DATA SUPPLEMENT

39

The manufacturing sequence on all the drills is somewhat similar. That for the 0.594-inch drill is as follows:

1. The stock is cut-off, centered, and ground to 0.578 inch diameter. 2. Grooves for the wear plates, the chip flute, and the seat for the carbide tip are milled. 3. The wear plates and carbide tip are brazed in place. 4. The stock is ground on centers to the correct diameter over the carbide inserts, leaving the body slightly undersize, in this case, The latter eliminates the need of relief or back-off on 0.578 inch. the drill. 5. Both centered ends are cut-off and the oil hole is drilled. 6. The drill tip is butt-welded to the conventional fluted-type

seamless-tube shank. 7. Finally, the drill is sharpened. This drill, as well as the other sizes, may be made from drill

rod. Better results, however, are obtained with S.A.E. 3115 steel Aerocase hardened to a depth of 0.003 to 0.005 mcn before brazing

in the wear plates and tip.

Case hardening minimizes the danger of picking up chips and slight tears on the soft core of the barrel when drilling. The 0.578 inch diameter drill will run up to 20 hours inches with ease. without sharpening and will take a feed of The machine used for drilling the 1.150-inch air-cylinder hole in the receiver body of 20-millimeter automatic cannon was originally built for a two-lipped drill with the chip return through the center of the drill extension. Chips would often plug this center hole, causing the stock to run out as much as 0.030 inch in 24 inches. This condition was overcome completely by the 1.150-inch drill The double lip was replaced by a single shown in the drawing. lip tipped with carbide and backed up with two carbide wear plates. Since this drill was designed, run-out in the receiver body has been held consistently within 0.008 inch in 24 inches. Chip breakers, ground as steps on the cutting edge, split the chips while drilling The success of this and reduce the possibility of the plugging. drill is partly due, of course, to the rigidity of the round extension tube compared with the conventional fluted seamless tube used on small drills. Another asset is the ease of removing the drill by simply unscrewing it from the extension tube. The 1.150-inch drill is used in a No. 420 W. F. & John Barnes horizontal drilling machine while running at a speed of 600 r.p.m. The speed should be higher, but due to the heavy cradle used for holding the work it is not essential. At the 600 r.p.m. speed, the drill feed is to 1 inch per minute, under which conditions the drill A feed can be used for 10 hours and more without resharpening. The tailof inches per minute can be used at higher speeds. stock of the machine is so constructed as to let the oil, under pres is inch smaller in sure, enter along the drill extension-which diameter than the drill. The oil flows along the two outside flats on the drill up to the point, and finally back through the flute and hole in the extension tube, carrying the chips with it.

i|

ii

|

i

40

AMERICAN MACHINISTS' HANDBOOK

The illustrations, Figs. 3 and 4, are self-explanatory. Gun-Barrel Reamers and Broaches. — Wood-packed reamers for finishing the bore of cannon of various sizes are still largely used in gun shops. One of these, such as used in the Watervliet Arsenal, is shown in Fig. 5. The dimensions of the various parts are given for four sizes, 37 mm., 75 mm., 3 in., and 105 mm. The wood-packed tool is a cutting head followed by two semiround wood inserts which support the bar in the bore. These inserts are made of hard maple which is kept under vacuum for It is then soaked in an 24 hours to remove all the moisture. The ends are waxed to keep the impregnating oil for 24 hours. wood from checking. When ready to use, the wood is turned 0.005 inch larger than the reamer size to ensure a rigid support for the bar. High-speed blades are used for the roughing ream and carbon steel for the finishing cut. The gun tube is first counterbored for a short distance to ensure the reamer's being started straight. As the wood packing must be replaced after each bore, this makes an expensive method both in material and in time. More modern practice is to use babbitt as a packing instead of wood, and carbide-tipped cutters instead of high speed and carbon. This has two advantages: the carbide cutters maintain their size for the whole length of the bore and so eliminate all chance of a taper hole, and the babbitt packing can be used for six or eight bores before they need to be replaced. The babbitt packings are turned with about 0.001-inch clearance instead of being oversize, as with the wood-packed reamers. Details of the babbitt-packed reamers are seen in Figs. 6 and 7. Portable -Boring -Bar Feeds and Speeds. — The Van Norman Machine Tool Co. recommends the following feeds and speeds for their cylinder-boring bars. Table 1. — Boring-Bar Feeds and Speeds Diameter of Hole in Inches

Depth of Hole in Inches

R.P.M. of Bar

Peed in Inches per Minute

10

355 344 285

if l|

1.9 to 3.8 2. 2 to 4. 25 2.6 to 5 . 25 Two-speed bars: 2.6 to 5. 34

14

3.49 to 7.5

18

4-35 to

3°

9

10

14

High Low High Low High Low

37s

220

234 162 169 117

2\

1S

iA

M M

1

Gun-Barrel Broaches. — Broaches are now used to cut the rifling grooves in gun barrels instead of the old, slow method of

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0.006

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screw

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Lead

Reodings for bose length bed token with lead screw inch for each addit stotionory;ada.00l ional feet of bed length

o

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as H

k

14

AMERICAN MACHINISTS' HANDBOOK

■T

3 E-6.

if 2?

11

II

WARTIME DATA SUPPLEMENT

o o

+1+1

o o

+1+1

o o

+1+1

EL •a

51

^

„

R S

15

136

AMERICAN MACHINISTS' HANDBOOK HYDRAULIC SYSTEMS ON MACHINE TOOLS

Increasing use of hydraulics for power and feeds of machine tools it necessary to know the factors that affect operation. According to John Sasso, oils should be checked for viscosity, stability, pour point, flash point, corrosive tendencies, emulsification, and foaming. Testing Oils. — Viscosity is a measure of the internal friction — with too high a viscosity, excessive fluid friction causes heating, Stability is ability of the oil loss of power, and sluggish action. makes

Such decomposition to resist decomposition over a period of time. results in gummy deposits on valves and moving parts, causing Pour point indicates the oil behavior sticking and jerky operation. at low temperatures, at which it becomes viscous enough to cause Flash point is the measure of the fire risk; in an open trouble. system the temperature at which the oil gives off inflammable vapors in an important consideration. When an oil is easily emulsified, the frothy mixture that results is compressible; this will cause errors in amount of ram and valve motion. Emulsification increases if certain compounds of sulphur, If the oil level is soaps, fatty oils, and organic acids are present. the foam cause oil to be lost by "bubbling over," uncover low, may and ing pump suction allowing air to enter the system. Faulty lubrication caused by thin oil is usually shown by inability of the system to develop and hold desired pressures, overheating of the pump, or a reduction in power output. Noisy operation and lack of positiveness in the drive indicate lack of oil and presence of air or gasified oil mixtures. Recommendations. — Only highly refined oils entirely free of abrasive or contaminating foreign matter should be used. High demulsibility, or water-separation ability, is not always essential, unless the system is subject to water leakage. On the other hand, low oxidizing and low carbon residue-forming tendencies are impor tant characteristics. Manufacturers' viscosity recommendations usually range from 140 to 1,200 seconds Saybolt at ioo°F., depending on the make of High pumping pressures and operating temperatures will pump. call for heavier oils, the range depending upon the type of system. Oilgear recommends an oil of approximately 320 seconds Saybolt universal viscosity at ioo°F. for general service, and lighter oils of 140 viscosity where temperatures between 30 and 45°F. prevail. Hele-Shaw suggest oil of approximately 1,000 seconds Saybolt at ioo°F. for maximum-pressure operations or high temperature. The Waterbury hydraulic system requires an oil of medium vis cosity, about 320 seconds Saybolt at ioo°F.

WARTIME DATA SUPPLEMENT Table

2.

— Hydraulic-System Difficulties and Remedies

Machine

Characteristics

Oil Characteristics

Slows down on tem perature rise

Oil too light

Erratic action,

Poor

foaming or aera tion of oil

Sluggish

Corrosion draulic parts

of hy system

demulsibility,

high surface tension of oil — Oil has ab sorbed moisture Viscosity too high

Too high in acidity,

oil may be com pounded of harmful ingredients

Sticking valves (hy draulic)

oil High oxidation, not properly refined

Excessive leakage

Oil too light and/or viscosity index too low; also loose con

nections or excessive clearances

Pump noisy

137

Oil viscosity too high,

excessive causing pressure drop in in take line, or intake line too small, creat ing excessive oil ve locities

Remedy

Use heavier oil to re duce in leakage pump, motor, cylin der, etc. Use oil with proper

demulsibility

Use viscosity specified by manuf acturerwhen sluggish at tempera on ture, especially use lowstarting, pour-point oils Specify acid-free min eral oil, neutraliza tion number of 0.10 maximum for com bined acidity, saponifiables less than 1 per cent Check operating tem Do not ex perature. ceed 140 to i6o°F. for best results. If temperature is satis to factory change stable high index oil Tighten all connec tions and check clear ances. If leakage is still excessive, use heavier or higher in dex oil Use higher index or lighter oil. Use oil of lower pour point. Check pump intake size and install larger line if necessary

The data in Table 2 are an extension of the table appearing on page 559 of the "American Machinists' Handbook." The sizes given are now in use, having been developed during the war.

SECTION IX METAL-CUTTING SAWS HACK AND BAND SAWS The experience of different makers and different users of metalNew conditions of operation cutting saws does not always agree. and new mixtures of metals have their effect on recommended The following data are recommendations from a wellpractice. known maker of saws for metal, Henry Disston & Sons, Inc.

POWER -HACK -SAW BLADES Table

1.

— To Obtain Greater Efficiency and Make Hack-Saw Blades Last Longer

Failure

Pulling out at pinhole

Premature

Cause

Correction

Blade drawn too tight Blade twisting in cut Feed too heavy

Reduce; see Table

Speed too great

Reduce

Incorrect tooth spacing

of teeth Use number recommended for mate

speed

wear

Stripping teeth

Reduce tension on blade. Allow just enough to hold it straight and pre vent twisting 2

to recommended

rial

Insufficient feed

Increase feed as mended

Dry cutting

Use coolant

Tooth spacing too coarse

number Use recommended

Teeth too fine for material 138

rial

recom

of teeth for mate

WARTIME DATA SUPPLEMENT

139

Table i. — To Obtain Greater Efficiency and Make Hack-Saw Blades Last Longer. — Continued Failure

Cause

Correction

Worn frame Frame out of line with

Check machine for wear and adjustment

vise

Crooked cuts

Blade loose in frame

Stock not tight in vise

Adjust Inspect

Feed too heavy

Reduce;

and

clamps

tighten

see

Table

2

Install new blade Start new cut. May re

Worn-out blade Hard spot in material

quire new blade Make adjustment

Insufficient tension Tooth spacing too coarse Use

of teeth number recommended for mate

Blades

breaking

rial

New blade in unfinished

Table Start new cut

Side strain on blade

Worn out.

Feed too heavy cut

Table

2.

Brass, cast: Soft

Hard

Copper

steel

Cold-rolled steel

Iron

pipe

Tubing: Steel

see

2

Change blade

— Recommendations for Cutting Specific Materials with Hack-Saw Blades Material

Tool

Reduce;

Number of Teeth

Strokes per

4 to 6

J35 to 150

60

iso

60 60 120 120 120

per

6 6 6 6

4 to

Inch

to 10 to 10 to 10

to 6

10

to

4 to 6

6

Minute

to

10

10

135 to 13s 13s 13s 90 13s

90

Feed, in Pounds

15° 120

to 6 to 14 6 to 10

13s 13s 13s

120 120

14 14

13s 13s

60 60

4

10

i5°

AMERICAN MACHINISTS' HANDBOOK

140

FLEXIBLE-BACK METAL BAND SAWS Table 3. — To Obtain Greater Efficiency and Make FlexibleBack Metal Band Saws Last Longer Failure

Stripping teeth

Premature wear and loss of set

Breaking

Cause

Tooth spacing too coarse Use recommended spacing Starting cut at extremely Start cut where several thin section of material teeth will contact mate or on a corner rial at same time Reduce; see Table 5 Speed too fast so that teeth Adjust Rubbing in guides project beyond guides — also so that teeth pro Riding on wheels ject over edge of wheels If irregular cutting, use Twisting in the cut proper width saw for Adjust so that top and bottom guides are in

Guides set too far apart, allow band to twist

Always adjust guides as

Insufficient tension

Adjust tension to approx imately 300 pounds per inch of saw width Remove saw from ma chine or release tension. Where extreme differ ences of temperature

use

of line

radius

Misalignment of guides

Allowing band to remain in tension when not in

Cutting out

Correction

alignment

close as possible to piece being cut

will

occur, this practice prevent breakage

Misalignment of guides

Adjustment

Spacing of guides Set worn on one side due to contact with wheels or guides

Set as close as possible

Feed too heavy

made

Adjust

so

should

that

be

teeth

project beyond guides — also so that teeth pro ject over edge of wheels

Reduce feed or use coarser tooth saw

WARTIME DATA SUPPLEMENT Table

4.

— Recommended Band-Saw Widths

Width of Band Saw,

Inch

A A

Radius to Be Cut, Inches

Minimum

A A

i

1 4

A

A

i 0

4i 8

AMERICAN MACHINISTS' HANDBOOK

142

— Recommendations for Cutting Specific Materials with Hard-Edge Flexible-Back Metal-Cutting Band

Table

5.

Saws

Material

Aluminum: Solids

Sheets

Aluminum alloys:

Solids Irregular shapes Asbestos sheets Bakelite Brass castings: Soft Brass sheets and tubing. Bronze : Bars Castings Mouldings Cast iron

. .

Catalin

Copper Copper — nickel Bverbright

Everdur Fiber

Formica •••• • Hose — canvas and rubber. . Hose — metallic Inconel Iron bars Iron sheets (under A-inch) Metal wood

Mica Micarta

Monel metal Nickel silver Pipe Radiator core Rubber — hard Slate Steel: Chromium Cold-rolled Drill rod Heat-resistant High-speed Machinery Manganese Nickel Structural

Tool Tubing

Textolite Transite

per

Inch

S 8

to to

8

to to

12 8 10 8

Babbitt Hard

Number of Teeth

to

to to

10 10

to to to

10 10

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