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. .

.

..

,

..

.

%.

VALI DATI ON NOTI CE1

23 Mar ch 1990

ANSI / ASME B1. 2- 1983

16

May 1983

ANST/ ASME Bl . 2- 1983, adopt ed on 25 Oct ober 1984, has been r evi ewednd determ ned

t o be cur r ent .

Cust odi ans:

Ar my

-

AR

Navy - AS

Ai r Force

-11

Revi ew Act i vi t i es:

.r. Ar my - AT, AV, GL,

ME

User Act i vi t y:

Navy - EC

Ci vi l Agency Coor di nat i ng Act i vi t i es:

Commer ce - NI ST

DOT - ACO, APM, FAA, FRA, NHT

GSA

-

FSS, PLD

HUD

-

HSRS

J us t i ce - FPI

NASA

-

J FK, LRC, MSF

USDA - AFS

Pr epar i ng Act i vi t y:

DLA

-

IS

AREA THDS

DI STRI BUTI ON STATEMENTA. Appr oved f or publ i c r el ease; di st r i but i on

s

unl i m ted.

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Errata

to

ANSI/ASME Bl.2-1983

The Errata correction listed belowapplies

to

ANSI/ASME

B1.2-1983,

Gages and Gaging

for Unified Inch Screw Threads.

Page

Location Change

87 Table 11

Under

column 8, change thirdntry

from

.3744

o

.3739

MAY 1992

THE AMERICAN SOCIETY

OF

MECHANICAL

ENGINEERS

345 East 47th Street, New York, N.Y.

10017

N0058E

yright ASME International

ided by IHS under license with ASME Licensee=EMBRAER/1829800100, User=Donato, Thiago

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A N

ASME B L - 2

8 3

A M E R I C A N

2 5 7 5 5 3 2

0 0 3 3 b 5 1

43 - b

N A T I O N A L

S T A N D A R D

Gages and Gaging for

Unified Inch Screw Threads

ANSI/ASME B1.2-1983

( R E V I S I O N OF AN SI B1.2-1974)

S PONSOREDA N DP U B L I S H E DB Y

T H E M E R I C A N O C I E T Y OF M E C H A N I C A L N G I N E E R S

U n i t e d n g i n e e r i n g e n t e r 3 4 5 East 4 7 t h t r e e t e w o r k , N. Y. 1 001

7

7


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This Standard wi ll be revised when the Society approves the issuance

of

a

new edition. There will

be no addenda o r written interpretations

of

the requirementsof this Standard issued to this Edition.

Date of Issuance: June

15,

1984

This code or standard was developed under procedures accredited

s

meeting the criteria for Ameri-

can National Standards. The Consensus Committee that approved the code or standard was balanced

to assure that individuals from competent and concerned interests have had an pportunity to partici-

pate. The proposed code or standard was made available for publ ic review and comment which pro-

vides an opportunity for additional public inpu t from industry, academia, regulatory agencies, and in

the public-at-large.

ASMEdoes not "approve," rate,"or endorse"any tem, construct ion, proprietary device, or

activity.

ASME does not take any position with respect to the valid ity of any patent rights asserted in con-

nection with any items mentioned in this document, and does not undertake o insure anyone utili zing

a standard against liability for infringement

of

any applicable Letters Patent, nor assume any such

lia-

bili ty. Users of a code or standard are expressly advised that determination of the validity of any such

patent rights, and the risk

of

infringement of such rights,

is

entirely their own responsibility.

Partic ipation by federal agency representative(s) or person(s) affiliated with industry

is

not to be in-

terpreted

as

government or ndustry endorsementof this code or standard.

ASME does not accept any responsibil ity for interpretations of this document made by individual

volunteers.

No part of this document may be reproduced in any form,

in an electronic retrievalsystem or otherwise,

without

the

prior written permissionof the publisher,

Copyright

0

1984 by

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

Al l Rights Resewed

Printed in U.S.A.


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ASME B I - 2 8 3 2 5 7 5 5 1 2 OOll1653 2

FOREWORD

(This Foreword is no t part

of

Amer ican Nat iona l S tandard ANSVA SME 61.2-1983,

Gages and Gaging for Un i f ied Inch Screw Threads.)

American National Standards Committee B1 for the Standardization of screw threads

was organized in 1920 as Sectional Committee B1 under the aegis of the American Engi-

neering Standards Committee (later the American National Standards Association, then

the United States of America Standards Institute and,as of.October 6, 1969, the American

National Standards Institute, Inc.), with the Society of Automotive Engineers and the

American Society of Mechanical Engineers as. oint sponsors.

In 1982, American National Standards Committee B1 was reorganized as the ASME

Standards Committee BI, and since then it has operated under the American Society of

Mechanical Engineers Procedures t o produce and update standards which may become

ANSI Standards after final approval by the American National Standards Institute.

A declaration

of

accord with respect to the unification of screw threads was signed on

November 18, 1948, by representatives of the services and industry of the United States,

the United Kingdom, and Canada.The ANSI Unified Screw Thread Standard BI., through

the quadripartite standardization greement (QST AG) 247, Unified Threads, is subject to

an international standardization agreement through the instrumentality of the American-

British-Canadian-Australian Army Standardization Program, which recognizes BI.

I

as

a standard forUnified Threads when it is required to effect the interchangeability of parts

and equipment between the armies of the participating nations.

The first American National Standard for Screw Thread Gages and Gaging was pub-

lished as ASA B1.2-1941 to supplement the parent Standard SA B1.l-1935, ScrewThreads

for Bolts, Nuts, Machine Screws and Threaded Parts. That Standard was revised and re-

published as a Unified Standard ASA Bl.1-1949 and again as ASA Bl.1-1960. The Uni-

fied Gage Standard was republished as ASA B1.2-1951 and USA B1.2-1966.

On February 9, 1973, a meeting was held by the Department of Commerce at the Na-

tional Bureau of Standards, Washington, D.C., attended by representatives of government

and industry screw thread interests. With the goal of eliminating parallel‘standards, those

at the meeting recommended that theNBS Handbook H-28 be converted into a coordinat-

ing document for government screw thread standards wherein sections of H-28 would be

replaced by single page references to existing industry standards. It was further recom-

mended that the chairmanof American National Standards Committee B1 set up a group

to clearly define and establish identified levels of acceptability for screw threads.

At an American National Standards Committee 1 meeting held on May 3, 1973, unani-

mous approval was given to t he following motion: “The BI Committee recognizing the

needs of industry for different levels of acceptability for screw threads, establishes new

scopes for StandardsB 1.1 and B 1.2 and sets up a new standard, B1.3.” References to con-

formance criteria were removed from ANSI B1.2-1974 and additional gages and gaging

data were added to suit additional conformance requirements specified in ANSI B1.3 or

other B1 thread documents.

This new publication, designated ANSIIASME B1.2-1983, has had considerable new

material added to cover the many options of gages and measuring equipment shown in

ANSI B1.3, Screw Thread Gaging Systems for Dimensional Acceptability. I t has also re-

...

111


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ASME B 3 - 2 83

2 5 7 5 5 3 2 OOL365q

L

applied HI and

LO

to function as NOT

GO

gages and has eliminated gages with pitch di-

ameter outside product thread limits. ANSI B1.2 was approved by the ASME Standards

Committee B1 on March 18, 1983.

The proposed standard was submitted by the ASME Board of Standardization to the

American NationalStandardsInstitute. It was approved and formally designated an

American National Standard

on

May

16, 1983.

iv

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ASMESTANDARDSCOMMITTEE

B I

Standardization and Unification

of

Screw Threads

(The fol lowing is the roster f the Commi t tee a t the t ime o f approva l o f th is S tandard.)

OFFICERS

D. J. Emanuell i , Chairman H.

W.

Ell ison, Vicehairman

C. E. Lynch,

Secretary

COMMITTEE

P E RS O NNE L

AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC.

G. G . Gerber, McDonnel l Douglas, St. Louis, M issouri

H. Borrman, Alternate, Sperry Gyroscope Division, Grea t Neck, Ne w York

AMERICAN IRON AND STEEL INSTITUTE

F.

Dallas,

Jr.,

Saw hil l Tu bular Division, Sharon, P ennsylvania

AMERICAN MEASURING TOO L MANUFACTURERS ASSOCIATION

D.

Dodge, Pennoyer-Dodge Company, Glendale, California

C .

W.

Jatho,

Alternate,

Ame rican Measu ring Tool Manufacturers Association, Bi rmingham, Michigan

AMERICAN PIPE FllT lNG S ASSOCIATION

W. C. Farrell , Stockham Valves and Fittings, Birmingham, Alabama

DEFENSE INDUS TRIAL SUPPLY CENTER

E. Schw artz, Defense Industria l Supp ly Center, Philadelphia, P ennsylvania

F. S.

Ciccarone,

Alternate,

Defen se Industrial Supply Center, Philadelphia, Pennsylvania

ENGINE MANUFACTURER S ASSOCIATION

G.. A. Russ, Cum mins Engine Company, Columbus, Indiana

FARM AND INDUSTRIAL EQUIPMENT INSTITUTE

J. F. Nagy, Ford.Motor Company, Dearborn, Mich igan

INDUST RIAL FASTENERS INSTITUTE

R .

B . Belford , Indus trial Fasten ers Institute, Cleveland, Ohio

R. M.

Harris, Bethlehem Steel Company, Lebanon, Pennsylvania

K . E. Mc Cullo ugh , SPS Technologies, Inc., Je nkintown, Pennsylvania

J.

C. Mc Mu rray , Russel l, Burd sal l and Wa rd nc., Mentor, Ohio

J. A.

Tri l l ing, Holo-Krome Company, We st Hartford, Connecticut

E. D. Spengler, Alternate, Bethlehem Steel Company, Lebanon, Pennsylvania

MANUFACTURERS STANDARDIZATION SOCIETY OF THE VALVE AND FllTlNG INDUSTRY

W. C. Farrel l , Stockham Valves and Fitting, Birmingham, Alabama

MET AL CUTTING TOOL INSTITUTE (TAP AND DIE DIVISION)

N. F. Nau, Union/Butterf ie ld, Athol , Massachusetts

A.D. Shepherd, Jr., Alternate, Union/Butterf ie ld, Derby Line, Vermon t

NATIO NAL AUTOMATIC SPRINKLER AND FIRE CONTROL ASSOCIATION, INC.

W.

Testa, Grinne ll Fire Protec tion System s Company, Inc., Providence, Rhode Island

R .

P. Fleming,

Alternate,

Nationa l Automa tic Sprinkler and Fire Co ntrol Asso ciation, nc., Patterson, N ew York

V



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A S M E

8 3 . 2

83

M

2 5 9 5 5 3 2 0 0 1 3 6 5 b

8 M

NATIO NAL ELECTRICAL MANUFACTURERS ASSOCIATION

J.

L. Gri ff in, W heatland Tube Company, Wheatland, Pennsylvania

J. B. Levy, G eneral Electric Company, Schenectady, N ew York

F. F. Weingruber, Westinghouse Electric Corp., Pittsburgh, Pennsylvania

W .

R .

Wi l l i fo rd ,

Alternate

National Electr ical M anufacturers Association, W ashington, D.C.

NATIONAL MACHINETOOL BUILDERS ASSOCIATION

R .

J.

Sabatos, The Cleveland Twist Dri l l Company, Cleveland, Ohio

D.

R .

Stoner, Jr., Teledyne Landis Mach ine, Wayneshoro, Pennsylvania

NATIONAL SCREW M ACHIN E PRODUCTS ASSOCIATION

T. S . Meyer, Fischer Spe cial Manuf actu ring Company, Cold Spring, Kentucky

H.

A . Eichstaedt, Alternate Nationa l Screw Ma chine Produc ts Association, Brecksvil le, Ohio

SOCIETY OF AUTOMOTIVE ENGINEERS

H. W. El l ison, General Motors Technical Center, Warren. M ichigan

SOCIETY OF MANUFACTURING ENGINEERS

D.

Davidson, Morse/Hem co Corporation, Holland, Michiga n

TUBULAR RIVET AND MACHINE INSTITUTE

R . M. Byrne, Indus try Service Bureaus, Inc., Wh ite Plains, New York

U.S. DEPARTMENT OF THE AIR FORCE

R . P. Stewart, Wright-Patterson, Ohio

U S . DEPARTMENT OF THE ARM Y

F. J. Clas, U S . Department of the Army, W atervliet, N ew York

J.

C rowl ey , U S . A rm y Ma te r i a lDevelopment and Readiness Command, Alexandria, Virginia

F.

L. Jones, Alternate U.S. Army Missle Command, Redstone Arsenal, Alabama

U S . DEPARTMENT OF DEFENSE

E. Schwartz, Defense Industrial Supply Center, Philadelphia, Pennsylvania

U. S. DEPARTMENT OF THE NAVY

C. T. G ustafson, Portsmouth Naval Shipyard, Portsmouth, New Hampshire

INDIVIDUAL MEMBERS

C. T. Appleton, Jefferson, Massachusetts

J.

Boehnlein, PMC Industr ies, Wickl i ffe, Ohio

R . Browning , Southern Gage Company, Erin, Tennessee

R . S. Cham erda, The Johnson Gage Company, Bloomfield, Connecticut

J. F.

Cramer, Des Moines, Washington

E. W. Dresc her, Lancaster, Pennsylvania

D.

J.

Emanuel l i , Greenfield Tap and Die, Greenfield, Massachusetts

C . G. Erickson, Colt Industries - ter l ing Die Operation, West H artford, Connecticut

S.

I. Kanter, P.E., The Hanson-Whitney Company, Hartford, Connecticut

R . W.

Lamp ort, Th e V an Keuren Company, Watertown, Massachusetts

A.

R .

Machel l ,

Jr,,

Xerox Corp., Rochester, Ne w York

A. E.

Masterson, Watervl iet, New York

R . E. Mazzara, Ge ometric Tool, Ne w Haven, Connecticut

P. V. Pastore, Regal Beloit Corp., So uth Beloit, Il l inois

M. M. Schu ster, Hi-She ar Corporation, Torrance, California

A.

G. Strang, Boyds, Maryland

A.

F.

Thibodeau, Swanson Tool Man ufacturing, lnc., We st Hartford, Connecticut

J.

W.

Turton, The Bendix Corp., Greenfield, Massachusetts

Subcommittee

B I .2

- Screw Thread Gages and Gaging

R .

Browning, Chairman Southern Gage Company, Erin, Tennessee

A. F. Thibodeau, Secretary Swanson Tool Manufacturing, Inc., West Hartford, Connecticut

P.

F.

Bitters, Greenfield Tap and Die, Greenfield, Massachusetts

J. Boehnlein, PMC Industr ies, Wickl i ffe, Ohio

vi


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D. Cadieux, Greenfield Tap and Die, Greenfield, Massachusetts

R .

S.

Chamerda, The Johnson Gage Company, Bloomfield, Connecticut

M.

Davidson, Morse/Hemco Corp.. Holland, Michigan

D. Dodge, Pennoyer-Dodge Company, Glendale, California

H. W. Ellison, General Motors Technical Center, Warren, Michigan

J.

J.

Fiscella, Latham, New York

G. Garcina, Indianapolis, Indiana

C. T. Gustafson, Metrology Laboratories Division, Portsmouth, New Hampshire

S.

1. Kanter, The Hanson-Whitney Company, Hartford, Connecticut

R .

W.

Larnport, The Van KeurenCompany, Watertown, Massachusetts

A.

E.

Masterson, Watervliet, New York

K. E. McCullough, SPS Technologies, Inc., Jenkintown, Pennsylvania

J.

C. McMurray , Russell, Burdsall and Ward, Inc., Mentor, Ohio

J.

Preziosi, Amerace-Esna Corp., Union, New Jersey

M. M.

Schuster, Hi-Shear Corp., Torrance, Califo rnia

E.

Schwarfz, Defense Industrial Supply Center, Philadelphia, Pennsylvania

A. G. Strang, Boyds, Maryland

J. W. Turton, The Bendix Corp., Greenfield, Massachusetts

A. Zaverucha, McM ellon Brothers, Stratford, Connecticut

Task Group

B I.I -

Gages and Gaging

for

Metric

M

Screw Threads

C.

G.

Erickson,

Chairman,

West Hartford, Connecticut

R .

Browning,

Secretary,

Southern Gage Company, Erin, Tennessee

R.

S.

Charnerda, The. Johnson Gage Company, Bloomfield, Connecticut

M. Davidson, H. E. Morse Company, Holland, Mich igan

D. Ernanuelli , Greenfield Tap and Die, Greenfield, Massachusetts

S.

1. Kanter, The Hanson-Whitney Company, Hartford, Connecticut

R .

W. Lamport, The Van Keuren Company, Watertown, Massachusetts

K. E. McCullough, SPS Technologies, Inc., Jenkintown, Pennsylvania

J.

C. McMurray, Russell, Burdsall, and Ward, Inc., Mentor, Ohio

E.

Schwartz, Defense Industrial Supply Center, Philadelphia, Pennsylvania

A.

G. Strang, Boyds, Maryland

V i i



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A S M E B I - 2 83 m

2 5 7 5 5 3 2

0033658

3

m

CONTENTS

...

Foreword ........................................................................

111

Standards Committee Roster

.......................................................

V

1

Introduction

................................................................ 1

1.1 References

.............................................................

1

1.2 Classification ........................................................... 1

1.3 Federal Government Use ................................................. 1

2

Basic Principles

............................................

;

. . . . . . . . . . . . . . . .

1

2.1 Accuracy in Gaging ..................................................... 1

2.2 Limitations of Gaging

................................................... 1

2.3 Determining Size of Gages

...............................................

10

2.4 Standardemperature ................................................... 10

3 General Practice ............................................................

10

3.1 General Design ......................................................... 10

3.2 Types

of

Gages ......................................................... 10

3.3 Interpretation of Tolerances

..............................................

10

3.4 Direction of Tolerances on Gages

.......................................... 10

3.5

Standardhread Gage Tolerances ......................................... 11

3.7 Tolerances on Half-Angle

................................................

11

3.8 Check of Effect of Lead andFlank Angle Variations onProduct Thread

.......

11

3.9 Calibration Requirements andtandards

...................................

11

3.6 Tolerance on Lead

......................................................

11

4 Types of Gages for Product InternalThread ..................................

4.1 GO Working ThreadPlug Gages

..........................................

4.2 NOTGO (HI) ThreadPlug Gages

.........................................

4.3 Thread Snap Gages

-

O Segments or Rolls

..............................


-

OT GO (HI) Segments or Rolls .....................

4.5 Thread Snap Gages Minimum Matehal: Pitch Diameter Cone and


-

Minimum Material: Thread Groove Diameter

Vee ..................................................................

Type

................................................................

4.7 Thread-Setting Solid Ring Gages

..........................................

4.9 Snap and Indicating Gages to Check Major Diameter of Internal Thread

.......

4.10 Functional Indicating Thread Gages for Internal Thread

......................

4.11 Minimum-Material Indicating Thread Gages for Internal Thread

...............

4.12 Indicating Runout Thread Gage for Internal Thread

.........................

4.13 Differential Gaging

......................................................

4.8 Plain Plug. Snap. and Indicating Gages to Check Minor Diameter of

InternalThread .......................................................

11

11

13

14

20

20

23

24

24

28

28

33

33

37

ix



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4.14 Pitch Micrometers ...................................................... 39

4.15 Thread-M.easuring Balls

..................................................

39

4.16 OpticalComparatornd Toolmaker’s Microscope

...........................

39

4.17 Profileracingnstrument

...............................................

40

4.18 Surface Roughness Equipment ............................................ 40

4.19 Roundnessquipment ................................................... 40

4.20 Miscellaneous Gages and Gaging Equipment ................................ 40

5 Types

of

Gages for Product External Thread

.................................. 40

5.1 GOWorkingThread Ring Gages

..........................................

40

5.2 NOT GO (LO) ThreadRing Gages

........................................

128

5.3 Thread Snap Gages O Segments or Rolls

..............................

129

5.4 Thread Snap Gages - OTGO (LO) Segments or Rolls .................... 131

5.5 ThreadSnap Gages one nd Vee

......................................

133

5.6 Thread Snap Gages -Minimum Material: Thread Groove Diameter Type

.....

133

5.7 Plain Ring and Snap Gages to Check Major Diameter of Product

ExternalThreads

......................................................

133

5.8 Snap Gages forMinor Diameter of ProductExternalThreads .................

135

5.9 Functional ndicatingThread Gages for ExternalThread ..................... 135

5.10 Mimimum-Material ndicatingThread Gages for ExternalThread

.............

139

5.12 Differential Gaging ...................................................... 139

5.13 WToleranceThread-Setting Plug Gages ................................... 143

5.14 Plain Check Plug Gages for Thread Ring Gages

.............................

148

ExternalThreads

......................................................

148

5.16 Indicating Gages to Check MinorDiameter

of

ExternalThread

...............

148

5.17 Thread Micrometers .................................................... 159

5.18 Thread-Measuring Wires

.................................................

159

5.19 Optical Comparator nd Toolmaker’s Microscope

...........................

159

5.20 Profile Tracingnstrument

...............................................

160

5.21 Electromechanical Lead Tester ............................................ 160

5.22 Helical Path Attachment Used With GO Type Thread Indicating Gage

.........

160

5.23 Helical Path Analyzer

...................................................

160

5.24 Surface Roughness Equipment

............................................

161

5.25 Roundness Equipment

...................................................

161

5.26 Miscellaneous Gages andGagingEquipment

................................

161

5.11 IndicatingRunout Gage forExternalThreads

..............................

139

‘5.15 Indicating Plain Diameter Gages-Major Diameter

of

Product

Figures

1Maximum-MaterialGOFunctional Limit

.........................................

12

2PartialEndThreadsand Chip Grooves

...........................................

14

3

NOTGO HI) FunctionalDiameter Limit

........................................

16

4ThreadSnap Gages -Maximum-Material GO Functional Limit ................... 19

5Thread Snap Gages- OT GO HI)FunctionalDiameter Limit

...................

21

6 Thread Snap Gages

-

Minimum-Material Pitch Diameter Limit

-

one and Vee

. . . . .

22

7Thread Snap Gages Minimum-Material Thread Groove Diameter Limit

...........

23

8Thread Form of Solid Thread-Setting Ring Gages .................................. 26

9MinorDiameter Limit

-

ylindrical Plug Gages

..................................

27

10 Indicating Plain Diameter Gages-Max.-Min. Minor Diameter Limit

11 Snap and Indicating Diameter Gages

-

Max.-Min. Major Diameter

and Size ................................................................... 29

Limit and Size

..............................................................

30

X

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A S M E

BL.2

83 W

2595512 O O l l b b O T

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

Indicating Thread Gages.aximum-Material GO Functional Limit and Size ......

Indicating Thread Gages.inimum-Material Pitch Diameter Limit and

Size.one and Vee .......................................................

Indicating Thread Gages.inimum-Material Pitch Diameter Limit

and Size-BallandR adius .................................................

Indicating Thread Gages

-

iameter Runout

-

Minor to Pitch

.....................

Indicating Thread Gages- ifferentlal Gaging ........: .........................

Inside Micrometer, Caliper Type

................................................

Maximum..M aterial GO Functional Limit

........................................

NOT GO (LO) Functional Diameter Limit .......................................

Thread Snap Gages

-

Maximum-Material GO Functional Limit ...................

Thread Snap Gages

-

OT GO (LO) Functional Diameter Limit ...................

Thread Snap Gages

-

Minimum-Material Pitch Diameter Limit one and Vee

.....

Thread Snap Gages

-

Minimum-Material Thread Groove Diameter Limit

...........

Major Diameter Limit

.........................................................

Minor Diameter Limit Snap Type

................................................

and Size ...................................................................

andsize-ConeandVee ....................................................

Limit and Size

..............................................................

Indicating Thread Gages-Maximum-Material GO Functional Diameter Limit


-

Minimum-Material Pitch Diameter Limit

Indicating Thread Gages Minimum-Material Thread Groove Diameter

Indicating Thread Gages- iameter Runout-Major to Pitch

.....................

Indicating Thread Gages- ifferential Gaging

...................................

Thread Form of Truncated Thread-Setting Plug Gages

.............................

Thread Form of Full-Form Thread-Setting Plug Gages

............................

Indicating Plain Diameter Gage

-

Max.-Min. Major Diameter Limit and Size ........

Indicating Diameter Gages-Max.-Min. Minor Diameter Limit and Size

............

Indicating Gage ..............................................................

ndicating Gages- elical Pa th Attachment Used With GO Type

31

34

35

36

38

39

127

129

130

132

134

135

136

137

138

140

141

142

144

146

147

149

150

160

Tables

1 Screw Thread Gages and Measuring Equipment for External Product

2 Screw Thread Gages and Measuring Equipment for Internal Product

Thread Characteristics ......................................................

2

Thread Characteristics ......................................................

6

3 Recommended Widths for Chip Grooves ........................................ 13

ThreadedandPlain Gages for Unified Externaland nternalThreads ............. 15

Setting Gages for Unified Thread Working Gages .............................. 17

6 X Gage Tolerances forThread Gages

............................................

18

7W Gage Tolerances forThread Gages

...........................................

25

9Constants orComputingThread Gage Dimensions

...............................

32

Screw Threads - imits of Size ............................................. 41

and 3B UnifiedScrew Threads- imits of Size ............................... 83

4 Specifications and Format for Tables 10 and 11- imits of Su e of

5

Specifications and Format for Tables 10 and 11- imits of Size

of

Thread-

8

Gage Tolerances for Plain Cylindrical Gages .....................................

28

10

Gages for Standard Thread Series. Classes 1A. 2A. 3A. 1B. 2B. and 3B Unified

11 Setting Gages for Standard Thread Series. Classes 1A. 2A. 3A. 1B. 2B.

12 Calibration Requirements and Standards for X Tolerance Thread Gages.

Indicating Gages. Plain Gages. and Measuring Equipment for External

ProductThreads ............................................................ 151

xi


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13 Calibration Requirements and Standards for

X

Tolerance Thread Gages.

Indicating Gages. Plain Gages. and Measuring Equipment for Internal

Producthreads

...........................................................

155

14 Calibration Requirements for Thread-andPlain-Setting Gages ..................... 159

Appendices

A Calibration and Inspection of Limit Gages. Snap Gages. Indicating Gages.

and Measuring Instruments

Al General

................................................................

163

A2 Threadlug Gage Calibration ............................................ 163

A3 ThreadRing Gage Inspection ............................................ 164

A4 Plainlug Gage Calibration

.............................................

167

A5 PlainRing Gage Calibration ............................................. 168

A6 Plainnap Gages ....................................................... 168

A7 Rolls With Zero Lead Thread Form Used on Snap and Indicating

Gages

...............................................................

168

A8 Inspecting PeripheralContacting Segments Used on External

ProductThread

......................................................

168

A9 Inspection

of

ThreadContact Segments Used on

InternalProductThread ............................................... 170

A10 Check for Magnification Discrepancies Due to Indicating

System Linkage

......................................................

170

Al

1

Calibration of Dial nd Electronic Indicators .............................. 170

A12 Assessment of Surface Quality

...........................................

171

B

Metrology

of 60

deg

.

Screw Threads

........................................ 173

B1 Wire Method of Measurement of Pitch Diameter (Thread Groove

Diameter)

.....................................

i ...................... 173

B2 Size of Wires

...........................................................

173

B4 Methods of Measurement UsingWires

....................................

176

B5 Standard Specification for Wires and StandardPractice in Measurement

of Wires of60 deg Threads

............................................

176

B6 General Formula or Measurement of Pitch Diameter

.......................

177

B7 Simplified Formula for Pitch Diameter

....................................

177

B8 Setting Measuring Instruments With Variable Measuring Force . . . . . . . . . . . . . . . 178

B9 Thread Balls ........................................................... 178

B10 Internal itch Diameter Measurement

.....................................

179

B3 Methods of Measuring Wires Considering the Effect of Deformation . . . . . . . . . . 173

Figure

B1 A Three-Wire Method of Measuring Pitch (Thread Groove)

Diameter of ThreadPlug Gages ............................................. 174

Tables

Al

Minimum

Magnification ....................................................... 164

A2 60 deg. Included Thread Angle

.................................................

165

A3 Lengths of AGD Taperlock and Trilock Thread Plug Gage Blanks

A4 Lengths of AGD Thread Ring Gage Blanks and Total Thread Lengths

Selected FromANSI B47.1

..................................................

166

of Standard Truncated-Setting Plug Gage Blanks Selected from ANSI

B47.1 ..................................................................... 169

B1 Thread-Measuring Wires for 60 deg Screw Threads .............................. 175

and Wire Calibration. and Cylindrical Diameter for Wire Calibration

. . . . . . . . . . . . . . . . . . . .

176

Measurementnd Ball Calibration

...........................................

179

B2 Measuring Force for Over-Wire Measurements of External Pitch Diameter

B3 Measuring Force Over Balls for Internal Pitch Diameter

xii



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ANSI/ASME

61.2-1983

A NAMERICANNATIONAL STANDARD

AN AMERICAN NATIONAL TANDARD

GAGES AND GA GING FOR UNIFIED INCH SCREW THREADS

1 INTRODUCTION

This Standard provides essential specifications and

dimensions for the gages used on Unified inch screw

threads (UN and UNR thread form), and covers the

specifications and dimensions for the thread gages

and measuring equipment listed in Tables 1 and . The

basic purpose and use of each gage are also described.

1,I References

The latest editions of the following documents form

a part

of

this Standard, to he extentspecified herein.

American National Standards

ANSI B1.l

ANSI B1.3

ANSI B1.7

ANSI B46.1

ANSI B47.1

ANSI B89.1.6

ANSI B89.1.9

ANSI B89.3.1

Unified Inch Screw Threads (UN

and UNR Thread Form

Screw Thread Gaging Systems for

Dimensional Acceptability

Nomenclature, Definitions, and

Letter Symbols for Screw Threads

Surface Texture: Surface Rough-

ness, Waviness, and Lay

Gage Blanks

Measurement of Qualified Plain

Internal Diameters for Use

as

Master Rings and Ring Gages

Precision Inch Gage Blocks for

Length Measurement (Through 20

in.)

Measurement of Out-of-Round-

ness

for Federal Services, Section 6, the use of this Stan-

dard by the federal governmentwill

be

subject to all re-

quirements and limitations of FED-STD-H28/6.

2 BASIC PRINCIPLES

2.1 Accuracy n Gaging

Thread plug gages are controlled by direct measur-

ing methods. Thread ring gages, thread snap limit

gages, and indicating thread gages are controlled by

reference to the appropriate setting gages or direct

measuring methods or both.

2.2 Limi tations of Gaging

2.2.1 Product threads accepted by a gage of one

type may be verified by other types. It is possible,

however, that parts which are near a limit may be ac-

cepted by one type and rejected by another. Also, it

is possible for two individual limit gages of the same

type

to

be at opposite extremes of the gage tolerances

permitted, and borderline product threads accepted

by one gage could be rejected by another. For these

reasons, a product screw thread is considered accep-

table when it passes a test by any of the permissible

gages in ANSI B1.3 for the gaging system specified,

provided the gages being used are within the toler-

ances specified in this Standard.

1.2 Classification

In this Standard, the term NOT GO, previously

known as H I and LO, is used to identify functional

diameter thread gages.

1.3 Federal Government Use

When this Standard is approved by the Depart-

ment of Defense and federal agencies and is incorpo-

rated into FED-STD-H28/6,Screw Thread Standard

I

2.2.2 Gaging large product external and internal

threads equal to or greater than 6.25

in.

nominal size

with plain and threaded plug and ring gages presents

problems for technical and economic reasons. In

these instances, verification-may be based on use of

modified snap or indicating gages or measurement of

thread elements. Various types of gages or measur-

ing devices in addition to those defined in this docu-

ment are available and acceptable when properly cor-

related to this Standard. Producer and user should

agree on the method and equipment used.



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A S M E B 1 . 2

83

M 2 5 7 5 5 1 2 0 0 1 1 b b 3 5

H

GAGES AND GAGING FOR

UNIFIED INCH SCREW THREADS

-

\

ANSVASME 61.2-1

983

AN AMERICAN NATIONAL STANDARD

TABLE

1

S CREW THRE A D GA GE S A ND ME A S URING E QUIP ME N T FOR

EXTERNAL PRODUCT THREAD CHARACTERISTICS

T

Unif ied Inch Threads

NOT

GO

Functional

Diam.

Maximum

Material

CO

I

-

-uric.

Limit

Func. Func.

Limit I

Size

hread Gages

and

Measuring Equipment

1 Split or Solid Threaded Rings (ANSI 847.1)

1.1 GO

1.2

NOT GO (LO)

e

2 Thread SnapGages

2.1 G O

segments

2.2 NOT

G O (LO)

segments

2.3

G O

rolls

2.4 N O T G O

(LO)

rolls

e

2.5 Minimum material

-

itch diameter type-cone and ee

2.6 M in im um material -th read groove diameter

type- one only

3 Plain Diameter Gages

3.1 Plain cylindrical ring for major diameter

3.2 Major diameter snap type

3.3 Mi no r diameter snap type

3.4 Maximum and minimum major diameternap type

3.5 Maximum and min imum minor diameter nap type

4


Having either two contacts at 180 deg. or three contacts

a t 120 deg.

4.1 G O segments

e

e

e e

.3 G O rolls

e

4.5 Minimum

mater ia l -p i t chd iameter type-coneandvee

4.6 M in im um material- hread groove diameter type

- one only

4.7 Major diameter and pitch diameter runoutage

2



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UNIFIED INCH SCREWTHREADS

' ASME 8 1 . 2

83 W

2 5 7 5 5 1 2 0011664 7 =

A N S V A S M E 61.2-1983

. AN AMERICAN NATIONAL STANDARD

3

-7

Surface

Texture

N



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` , , ,

` , ,

` , , , ,

` `

` ,

` , , - ` - ` , ,

` , ,

` ,

` , ,

` - - -

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A S M E 81.2

8 3

2 5 7 5 5 3 2 0 0 1 L b b 5

9

ANSIIASME B1.2-1983

AN AMERICAN NATIONALSTANDARD

GAGES AND GAGING

FOR

UNIFIED

INCH

SCREW THREADS

TABLE

1

SCREW TH READ GAGES AND MEA SURING EQUIPMEN T FOR

EXTERNAL PRODUCT T HREA D CHA RAC TERISTICS (CONT'D)

T

Unified Inch Threads

T

Minimu m Material

aximum

Material

GO

NOT

GO

Functional

Diameter

T

hd. Groove

Diam.

itch Diam.

Func

Size

Func.

l im i t

Func.

Func.

limit Size

hread Gages

and

Measuring Equipment

l imit

C1

-

.8 D i f f e r en t i a l s egm en t o r roll

( G O

pr o f i l e f o r one p i t chn l ength) used in com binat ion

with a

G O

i nd i ca t i ng gage t o y i e l d a d i am e t e r equ i va l en t

for var iat ion in lead ( including uniformity of helix);

and a minimum mater i a l i ndicat ing gage to y i e ld a

diameter equivalent for var i a t ion n f l ank angle

5 ndicat ing Plain Diame terGages

5.1 Major d i ameter t ype

5 .2 M i no r d i am e t e r t ype

6 Pi tch Microme ter Wi th Standard Contact s Approxim ate ly

~ ~~~~~

NOT G O

(LO)

P ro fi le ] C on e a nd Vee

7

Pitch MicrometerWi thModi f i edContact s Approximate ly

P it ch D i am e t e r C on t ac t ] C one and V ee

8

Thread-Measur ing Wi res Wi th Sui t able Measur ing Means

e

e e

O pt i ca l C om par a t o r and T oo l m ake r ' s M i c r os cope W i t h

Sui table Fixtur ing

1 0 Profile Tracing Equipmen t With Sui table Fixtur ing

A

11

Lead Measur ingMachineWi thSui tableFixtur ing

1 2 Hel i cal Path At t achment Used Wi th GOType Indicat ing Gage

i

3HelicalPathAnalyzer

14 P la in M i c r om e t e r and C a l i pe r s

-

Modi f i ed As Requi r ed

15Sur faceM eas u r i ngE qu i pm en t

4

6

R oundnes squ i pm en t

I

L

NOTE:

(1) Maximum minor d i ameter l imi t is a c c e p t a b l e w h e n p r o d u c t p a s s e s G O g a g e on U N and UNR threads .

4



- - `

`

` `

`

`

`

` ` `

`

- ` - `

`

`

`

` - - -

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ASME

B L - 2

83

2 5 7 5 5 3 2 O O L l b b b 0

m

ANSVASME

B1.2-1983

AN AMERICANNATIONALSTANDARD

i<

F

3

.

- ~.~

~ _ _ _ _ _


UNIFIED NCHSCREWTHREADS

TABLE 1 SCREW T HREAD G AGES AN D MEASUR I NG EQ UI PMENT F O R

EXTERNAL PRODUCT THREAD CHARA CTERISTICS (CONT'D)

Roundness of

Pitch Cylinder

Taper

of Pitch

Cylinder

l ead

Incl. Flank

Helix Angle

Size Variation Variation

-_

Major

Diameter

Minor

Diameter

Diam.

Runout

Major

to Pitch

Size

Surface

Texture

N

Root

Rad.

L

l im i timit

I2

1

Size

e

e

e

K 1

M

e

e

5



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ANSVASME

61.2-1

983


GAGES AND GAGING

FOR


TABLE

2

S CREW THRE A D GA GES A ND M E A S U RING E QUIP ME NT F OR

INTERNAL PRODUCT THREAD CHARACTERISTICS

Thread Gages

and

Measuring Equipment

1

Threaded

Plugs

(ANSI 847.1)

1.1 GO

1.2 NOT

GO (HI)

2 Thread SnapGages

2.1

GO

segments

2.2 NOT G O (HI) segments

2.3

GO

rolls

2.4 NOT

GO (HI)

rolls

2.5 Mi ni mu m material

-

itch diameter type - one

and vee


-

hread groove diameter type

-

one only

3 Plain Diameter Gages

3.1

Plain cylindrical plugs for mino r diameter

3.2 Ma jo r diameter snap type

3.3 Mi no r diameter snap type

3.4 Maximu m and minimum major diamet er snap type

3.5 Maximu m and minimu m minor diamete r snap type

4

indicating Thread Gages

Having either tw o contacts at 180 deg or three

contacts at 120 deg.

4.1

GO

segments

4.3

GO

rolls

Unified Inch Threads

Material

NOT

GO

Functional

Diameter

T

Minimum Material

Pitch Diam.

6

l imit Size

C1 C2

Thd. Groove

Diam.

l i m i t

D2

1

Size


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A S M E B 3 . 2 3 W 2 5 7 5 5 3 2Ö O L l b b 8 4 W

GAGESANDGAGING FOR


A N S V A S M E

61.2-1983

ANAMERICANNATIONALSTANDARD

TABLE 2 SCREW THREA D GAGES A N D MEASU-RING EQUIPMENT FOR

INTERNAL PRODUCT THREAD CHA RACTERISTICS (CONT'D)

Major

Diameter

f

imitize

[Note1)

-"-

Note

I )

~

Note

1)

iNote I

I--

(Note 1

7



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ANSI/ASME

61.2-1

983




TABLE 2 SCREW THREA D GAGES AN D MEA SURIN G EQUIPMEN T FOR

INTERNAL PRODUCT THREAD CHARACTERISTICS (CONT'D)

Thread Gages

and

Measuring Equipment


-

itch diameter type- one

and vee

4.6 Mi ni mu m material -thread groo ve diameter

type

-

one only

4.7 Mi no r diameter and pitch diam eter runout gage

4.8 Differentia l segment or ro ll

(GO

profile for one pitch in length)sed in combination

with

a

GO ndica ting gage to yield a diameter equivalent

for variation in lead (in cluding uniform ity o f elix), and

a

minimum material indicating gage to yield

a

diameter

equivalent for variation in flankngle

5 Indicating Plain Diameter Gages

5.1 Maj or diameter type

5.2 Mi no r diameter type

6 Pitch Microme ter With Standard Contacts [Approximately

NOT

GO (HI)

Profile] Cone and Vee

7 Pitch Micro mete r With Modi fied Contacts (Approximately

Pitch Diameter Contact) Cone and Vee

8 Thread-Measuring Balls Wi th Suitable Measu ring Means

9 Optical Comparator and Toolmaker's Microsco pe With

Suitable Fixturing andCast Replica

10

Profile Tracing Equipment With Suitable Fixturing

14Surface MeasuringEquipment

15

Roundness Equipment

Maximum

Material

G O

Func.unc.

limit Size

A l A 2

NOTE:

(1) Minimum major diameter limi t is acceptable when product passes GO gage.

8

Unifi ed Inch Threads

NOT GO

Functional

Diameter

+

I.

-

Minimum Material



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83 m

2 5 7 5 5 3 2 0 0 3 3 b 7 0

2

m

SME

8 3 . 2

A N S V A S M E 61.2-1983



UNIFIED INCH SCREWTHREADS

TABLE

2

SCREW T HREA D G AGES AN D MEA SURI NG EQ UI PM ENT F O R

INTERNAL PRODUCT THREAD CHA RACTERISTICS (CONT'D)

Taper

of Pitch

Cylinder

Roundness

of

Pitch Cylinder

Oval

180

deg.

Multilobe

120 deg.

lead

Incl.

Helix

Variation

Diam.

Runout

Root Minor

Rad. to Pifch

L M

Surface

Texture

i m i t

H

N

9



`

`

` `

`

`

`

` ` `

`

`

`

`

`

`

`

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10

-

ASME

B3.2 8 3 2 5 7 5 5 3 2

0033673

'4

ANSVASME B1.2-1983


2.2.3

Indicating gages for internal threads smaller

than 3 / 16 in. are not available.

2. 3 Determining Size of Gages

2.3.1 Measuring Pitch Diameter. The three-

wire method of determining pitch diameter size of

thread plug gages is standard for gages in this Stan-

dard. Refer to Appendix B.

2.3.2

Size limit adjustments of thread ring and

external thread snap gages are determined by their fit

on their respective calibrated setting plugs. Indicat-

ing gages and hread gages forproduct xternal

threadsare controlled by reference to appropriate

calibrated setting plugs.

2.3.3

Size limit adjustments of internal thread

snap gages are determined by their fit on their respec-

tive calibrated setting rings. Indicating gages and

otheradjustable hread gages for product nternal

threads are controlled by reference to appropriatecal-

ibrated setting rings or by direct measuring methods.

2.4 Standard Temperature

2.4.1

A temperature of 68°F (20°C) is the stan-

dard temperature used internationally for linear mea-

surements. Nominal dimensions of gages and product

as specified and actual dimensions as measured shall

be within specified limits at this temperature. For

screw thread gaging, the acceptable tolerance on the

standard temperature is 3~ 2° F (k 1C).

2.4.2 As product threads are frequently checked

at temperatures which are not controlled, it is de-

sirable that the coefficient of the thermal expansion

of gages be the same as that of the product on which

they are used. Inasmuch as the majority of threaded

product consists of iron or steel, and screw thread

gages are ordinarily made of hardened steel, this

condition is usually fulfilled without special atten-

tion, provided thread gages andproduct have sta-

bilized to the same temperature. When the materials

of the product thread and thegage are dissimilar, the

differing thermal coefficients can cause serious com-

plications and must be taken into account, nless both

product and gage at the time of gaging are at a tem-

perature

of:

a) 68°F k4"F (20°C +2"C) for 1 in. and smaller

6) 68°F k2"F (20°C +l°C) for sizes above 1 in.

to 3 in.


UNIFIED INCH

SCREW

THREADS

(C) 68°F +1"F (20°C +0.5"C) for sizes above 3

in. to 6 in.

3 GENERAL PRACTICE

3.1

General Design

The design of gages is specified only to the extent

that it affects the results obtained in the gaging of

product hreads, Moreover, to serve their intended

purposes satisfactorily, thread gages should be pro-

duced by the atestand best manufacturing tech-

niques. The type of steel or wear-resistant material

selected, together with the heat-treating and stabili-

zation processes, should provide wear life and dimen-

sional stability. Thread gaging elements should be

precisely manufactured to assure adequate refine-

ment of surface texture, prevention or elimination of

amorphous or smear metal, and uniformity of thread

form over the entire length of the gaging member.

3.2 Types of Gages

For GO thread gages, check either the maximum-

material limit or size to assure interchangeable assem-

bly. For NOT GO (HI and LO) thread gages, inspect

the NOT

GO

functional diameter limit.

For G O and NOTGO plain cylindrical plug or ring

gages and snap or indicating gages, check the limit or

size of the minor diameter of product internal threads

and the major diameter of product external threads,

respectively.

3.3 Interpretation

of

Tolerances

Tolerances on lead, half-angle, and pitch diameter

are variations which may be taken independently for

each of these elements and may be taken to the extent

allowed by respective tabulated dimensional limits.

The tabulated tolerance on any oneelement must not

be exceeded, even though variations in the other two

elements are smaller than he respective tabulated

tolerances.

3.4

Direction o f Tolerances on Gages

At the maximum-material limit (GO), the dimen-

sions of all gages used for final conformance gaging

are to e within the limits of size of the product thread.

At the functional diameter limit, using NOT

G O (HI

and LO) thread gages, the standard practice is to have

the gage tolerance within the limits ofsize of the

product thread, Specifications for gage limits are listed

in Tables 4 and 5.



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ASME B 3 - 2

83

m

2 5 7 5 5 3 2 0031672 b

GAGES'AND

GAGING

FOR


3.5 Standard Thread Gage To-lerances

Standard tolerances for thread-working gages,

thread-setting plugs, and setting rings are as follows:

( a )

W tolerance, shown in Table 7, represent the

highest commercial grade of accuracy and workman-

ship and are specified for thread-setting gages;

b)

X tolerances, shown in Table 6, are larger than

W tolerances andare used forproduct inspection

gages.

Unless otherwise specified, all thread ages and gaging

contacts which directly check the product threadhall

be X tolerance.

3.6

Tolerance on Lead

Cumulative effect of progressive or erratic helix

variation and thick or thin end thread Variations is

specified as an allowable variation between any two

threads not farther apart than the length of the stan-

dard taperlock or trilock gage, shown in ANSIB47.1.

In the case of setting plugs, the specified tolerance

shall be applicable to the thread length in the mating

ring gage or nine pitches, whichever is smaller. For

setting rings, the tolerance applies to a thread length

of three pitches. The tolerance on lead establishes the

width of a zone, measured parallel to the axis of the

thread, within which the actual helical path must lie

for the specified length of the thread. Measurements

will be taken from

a

fixed reference point located at

the start of the first ull thread to a sufficient number

of positions along the entire helix to detect all types

of lead variations. Th e amounts that these positions

vary from their basic (theoretical) positions will be

recorded with due respect to sign. The greatest varia-

tion in each direction [plus and minus

(*)I

will be

selected and he sum of their values, disregarding

sign, shall not exceed the specified tolerance. If the

variations are all in one direction, the maximum value

governs conformance. In the case of truncated set-

ting plugs, the lead variations present on the full-

form portionand the truncated portion of an individ-

ual gage shall notdiffer from each other by more than

0.0001 in. over any portion equivalent to the length

of the thread ring gage, or nine pitches, whichever is

less. (When linear lead and drunkenness are measured

as individual elements and the sum of these does not

exceed the tolerance specified, the gage is well within

tolerance.)

3.7 Tolerances

on

Half-Angle

Tolerances are specified for the half-angles rather

than the included angle to assure that the bisector of

the included angle will be perpendicular to the axis

11

ANSVÄSME B1.2-1983


of the thread within proper limits. The equivalent of

the variation romthe true thread form caused by such

irregularities

as

convex, concave or wavy flanks,

rounded crests, or slight projections on he thread

formshallnot exceed the tolerance permitted on

half-angle.

3.8

Check of Effect of Lead and Flank Angle

Variations on Produc t Thread

When this check is specified, there are two general

methods available forhe inspection procedures

involved.

(a) Direct Measurement

of

Lead and Half-Angleof

Flanks. The lead and flank angles of theproduct

thread may be measured by means of available mea-

suring equipment, such as thread indicating gages,

projection comparators, measuring microscopes,

graduatedcone points, lead measuring machines,

helix variation measuring machines, thread lank

charting equipment, etc. Diameter equivalents of such

variations from nominal maybe calculated: each

0.0001

in. variation in lead amounts to 0.00017 n.

(1.732 X .OOOOl) increase in functional pitch diameter

on external threads or a decrease in functional pitch

diameter on internal hreads for 60 deg. screwhreads.

The tangent of half-angle variation times 1 . 5 ~quals

the approximatemaximum change in functional pitch

diameter, based on a height of thread engagement of

0.6258 and equal half-angle variations.

b) Differential Gaging Utilizing Indicating Thread

Gages.

See Sections 4 and 5 for explanation and il-

lustration of differential gaging for internal and ex-

ternal threads.

3.9

Calibration Requirements and Standards

Calibration requirements and standards for X tol-

erance thread gages, snap gages, and indicating gages;

Z

tolerance plain gages and measuring instruments

are given in Table 12 for external product threads,

in Table13 for internal product threads, and in Table

14 for setting gages. See Appendix A for methods of

calibrating and inspecting gages.

4

TYPES OFGAGES FOR PRODUCT

INTERNAL THREAD

4.1 GO Working Thread Plug Gages

(Table

2-

Gage 1

.I

4.1

.I PurposeandUse. The

GO

thread plug

gage inspects the maximum-material GO functional

limit, A l , of product internal thread. The GO thread



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ASME

B3.2 8 3 m 2 5 7 5 5 3 2 0 0 3 3 b 7 3 8 m

ANSL'ASME

BI

.2-1983

AN A MERICAN NATIONAL STANDARD

GAGES AND GA GING

FOR

UNIFIED INC H SCREW THREADS

FIG. 1 MAXIMUM-MATERIAL GO FUNCTIONAL LIMIT

gage represents the maximum-material GO functional

limit

of

the product internal thread, and its purpose is

to assure interchangeable assembly of maximum-

material mating parts. GO thread pluggages must

enter and pass through the full-threaded length of the

product freely. The GO thread plug gage isa cumula-

tive check of all thread elements except the minor

diameter.

4.1.2 Basic Design. The maximum-material

limit on GO thread plus gages s made to the pre-

scribed maximum-material limit of the product in-

ternal thread, and the gaging length is equal to the

length of the gaging plug.

4.1.3 Gage Blanks. For practical and economi-

cal reasons, the design and lengths of the gaging plug

members have been standardized for various size

ranges and pitches (see ANSI

B47.1

or Table A3).

4. 1. 4 Thread Form. The specifications for

thread form are summarized in Table 4 and Fig. 1 .

4.1.5 Thread Crests.

The major diameter of the

GO thread plug gage shall be the same as the mini-

mum major diameter of the product internal thread

with a plus gage tolerance. The thread crests shall be

flat in an axial section and parallel to the axis.

4.1.6 Thread Roots. The minor diameter of the

GO thread plug gage shall be cleared beyond

a

p / 8

width of flat either by an extension

of

the sides of

the thread toward a sharp vee or by an undercut no

greater than

P/

maximum width and approximately

central.

4.1.7 Runout of Pitch and Major Cylinders.

On thread plug gages an eccentric condition produces

an oversize effective major diameter having a width

of flat less th an p/ 8, which may encroach on the min-

imum permissibIe imit for heroot profile of the

product internal thread. The permissible maximum

effective major diameter, as determined by adding

measurement of runout (full-indicator movement)

with respect to he pitch cylinder to he measured

12

,

fl

\,


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- A S M E

B I - 2

8 3

2 5 7 5 5 1 2 0 0 1 1 b 7 4 T =

~



major diameter, shall not exceed the maximum major

diameter specified.

4.1.8

Pitch Cylinder. The pitch cylinder shall be

round and straight within the gage pitch diameter

limits specified.

4.1.9

eadand Half-Angle Variation s. Lead

and half-angle variations shall be within the limits

specified. See Table 6.

4.1

IO incom plete Thread.

The feather -edge

at both ends of the threaded section of the gaging

member shall be removed. On pitches coarser than 28

threadslin., not more than one complete turn of the

end threads shall be removed to obtain a full-thread

form blunt start.See Fig. 2. On pitches 28 threadsl in.

and finer,

a

60 deg. chamfer from the axis of the gage

is

acceptable in lieu of the blunt start.

4.1

I 1 Chip Grooves.

Each

GO

thread plug

gage, except in sizes No. 8 (0.164in.) and smaller, shall

be provided with

a

chip groove at the entering end. On

reversible gages, a chip groove shall be provided at

each end. Chip grooves that are in accordance with

commercial practice are acceptable, such as a groove

cut at an ngle with the axis or a longitudinal groove

cut parallel with the axis and extending the complete

length of the gaging member. The groove shall be lo-

cated circumferentially at the start f the full thread,

and in all cases the depth shall xtend below the root

of the first full thread. The distance from the major

diameter of the thread plug to the crest of the con-

volution rise in front of the chip groove, due to the

radius of the convoluting tool, shall be a minimum of

H / 2 as shown in Fig.

2.

The beginning of the first

thread shall be full form. The recommended widths

for chip grooves are as shown in Table 3.

4.1.1

dentification. The

GO

thread plugs

should be identified by the nominal size, threadslin.,

thread series, GO,

PD,

and pitch diameter.

EXAMPLE:

k .

1/4-20

(or

.250-20) UNC G O PD.2175

4.2NOT GO (Hi) Thread Plug Gages

(Table

2

- Gage

1.2)

4.2.1

PurposeandUse. TheNOT GO (HI)

thread plug gage inspects the NOT

GO

(HI)

func-

tional diameter limit, B I ,of product internal thread.

The NOT

G O

(HI) thread plug gage represents the

13

ANSI/ASME B 1 2 - 1 983


TABLE 3 RECO M MENDE D W I DT HS

F O R CHI P G RO O VES

Chip Groove

Width, in.

Nominal

Diameter,

in.

M a x .

Min.

No.

8 0.164) and smaller No chip

groove

required

Above No. 8 0.164) to

and

including

No. 12 (0.216).036.026

Above

No.

12 (0.216)

to

and including

3/8 (0.375).052.042

Above 3/8 (0.375) to and including

1/2 (0.500)

0.067.057

Above 1/2(0.500)

to

and including

1

(1.000)

0.083

0.067

Above 1 (1.000) to and including1-3/4 (1.750)

0.130.067

Above 1-3/4 (1.750)

0.193.067

NOT GO (HI) functional diameter limit of the prod-

uct internal thread.

Thread plug gages when applied to the product in-

ternal thread may engage only he end threads (which

may not be representative of the complete thread).

Entering threads on product are incomplete and per-

mit gage to start. Starting threads on NOT

GO (HI)

plugs are subject to greater wear than the remaining

threads. Such wear in combination with the incom-

plete product hreads permits furtherentry

of

the

gage. NOT

GO (HI)

functional diameter isaccep-

table when the NOTGO (HI) thread plug gage pplied

to the product internal thread does not enter more

than three complete turns. The gage should not be

forced, Special requirements such as exceptionally

thin or ductile material, small number of threads, etc.,

may necessitate modification of this practice.

4.2.2

asic Design. To better check the maxi-

mum functional diameter limit, the flank contact is

reduced by truncating the major diameter, and the

length of the gaging element, where practica1,'is less

than that of the

GO

gage.

4.2.3'

age Bianks.

For practical and ecqnomic

reasons, the designs and lengths of the gaging ele-

ments have been standardized for various size ranges

and pitches (see ANSI B47.1 or Table A3).

4.2.4

hread Form. The specifications or thread

form are summarized in Table 4 and Fig.

3.

4.2.5

hread Crests. The maximum major di-

ameter of the NOT

GO (HI)

thread plug gage shall



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A N S V A S M E B1.2-1983


GAGES AND GAG ING FOR


Gr ind ing wheel o r

convo lu t i ng too l

,

'.

Remove inco mp lete thread

fo r one com ple te tu rn a t

bo th ends.

FIG.

2

PARTIAL

END

THREA DS AND CHtP GROOVES

be equal to the maximum pitch diameter of the prod-

uct internal thread plus 0 .5H with the gage tolerance

minus. This corresponds to a width of flat at the

crest of the gage equal to

0.25~.

ee Table

4.

4. 2. 6 Thread Roots.

The minor diameter of the

NOT GO (HI) thread plug gage shall be cleared be-

yond a

p/8

width of -flat by

an

extension toward a

sharp vee of the sides of the thread from theposition

corresponding to this approximate width; or by an

undercut to any dimension no wider than the width

resulting from

p/8

maximum width, either side of

and approximately central with the center line of the

thread groove.

4.2.7

Runout

of

Pitch and Major Cylinders.

The permissible maximum effective diameter, as de-

termined by adding measurements

of

runout (full-

indicator movement) with respect to the pitch cylinder

to the measured major diameter, shall not exceed the

maximum major diameter specified,

4.2.8 Pitch Cylinder.

The pitch cylinder shall

be round and straight within the gage pitch diameter

limits specified.

4.2.9 Lead and Half-Angle Variations. Lead

and half-angle variations shall be within the limits

specified. See Table

6 .

4.2.10 Incomplete Thread. The feather edge at

both ends of the threaded section of the gaging mem-

ber shall be removed. On pitches coarser than

28

threadslin., not more than one complete turn of the

end threads shall be removed to obtain a full-thread

blunt start. See Fig.

2.

On pitches

28

threadslin. and

finer, a 60 deg. chamfer from the axis of the gage is

acceptable in lieu of the blunt start.

4.2.1 1

Identification.

The NOTGO H1)thread

plug gage should be marked with the nominal size,

threadslin., thread series, class, NOT GO,

PD,

and

pitch diameter.

EXAMPLE:

1/4-20 (or .250-20) UNC-2B NO T GO PD.2224

4.3

Thread Snap Gages -

GO

Segments or

Rolls (Table 2 - Gages 2.1 and 2.3)

4.3.1 Purpose and Use.

The hreadsnap gage

with two G O threaded segments or two GO zero lead

14


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ASME B I - 2

83

2 5 7 5 5 3 2 00LLb7b 3

GAGESANDGAGINGFOR


ANSI/ASME BI .2-1983

AN AMERICANNATIONALSTANDARD

TABLE

4

SPECIFICATIONS A ND FO RM A T F OR TABLES 10 A N D 11- IMITS OF SIZE O F THREADED

A ND PL A IN GAGES FOR UNIFIED EXTERNAL A N D INTERNAL THREADS

Nominal

Size

and Threadslin.

1

Series Designation and Tolerance Class

2

~~

Gages for

External

Threads

Gages for

Internal

Threads

Thread gages

Plain gages

for major

diameter

Thread gages

Plain gages

for minor

diameter

CO

Pitch

diameter l

I

Minor

diameter l 4

Pitch

NOTGO(LO)

Minor

diameter

;

OT

GO

GO

NOT GO HI )

Major

9

diameter

Pitch

10

diameter

Major

11

diameter

Pitch

12

diameter

q

OT GO

Series Designation and Tolerance Class

15

(To be specified)

Of external thread to be checked

Max. pitch diameter of external thread;

gage tolerance minus

M a x . pitch diameterof external hread;

minus H/2; gage tolerance minus

Min. pitch diameter of external thread;

gage tolerance plus

Min. pitchdiameter of external thread

minus 0.25H; gage tolerance plus

Max.

major diameter of external

thread; gage tolerance minus

Min. major diameter of external

thread; gage tolerance plus

Min. major diameter of internal


Min. pitch diameter

of

internal thread;

gage tolerance plus

Max. pitch diameter of internal thread

plus H/2; gage tolerance minus

Max. pitch diameter of internal thread;


Min. minor diameter of internal


M a x . minor diameter of internal

thread; gage toLerance minus

Of internal thread to be checked

rolls inspects the maximum-material

GO

functional

limit, A l , of product internal thread, The setting of

the

GO

segments or rolls represents the maximum-

material

GO

functional limit of the product internal

thread, and its purpose is to assure interchangeable

assembly of maximum-material mating parts.The

segments or rolls theoretically engage over the full-

threaded length of the product. The segments or rolls

have a cumulative check

of

all thread elements except

the minor diameter.

Internal thread snap gages by design must have an

outside diameter of gaging elements below minor

diameter of internal thread in ordero enter. Thegage

checks all thread elements by sensing the resistance

of contact after being set to a master.

15

The GO thread snap gage can also indicate out-of-

roundness of pitch cylinder for

180

deg. ovality by us-

ing the gage at different internal diametral locations

on the product thread.

4.3.2

Basic

Design.

The

GO

segments and rolls

assembled into gage frames are the design of the in-

dividual gage manufacturer. The lengths of the two

threaded segments and he two thread rolls spaced

180 deg. apart are equivalent to the standard gage

blank lengths for practical and economic reasons. Se e.

Table A3 and Fig. 4. Internal product threadsess than

3/16 in, in diameter are not practical to check with

snap gages. GO thread segments shall engage

25

or

more of the product circumference. Product shall 'be



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ASME B I - 2 83 U 2 5 9 5 5 1 2 0011678

7



ANSI/ASME

61.2-1983


TABLE

5

S PE CIF ICA TIONS A N D FOR MA T FORTABLES

10

A N D 11

-

IMITS

OF

SIZE O F THREAD-

SETTING GAGES FOR UNIFIE D THR EA D WO RK ING AGES

1

2

-

(To

be specified)

Of external thread to be checked byage set

with plug

Max. majordiam. of external threadequals min.

major diam. of full portio n of GO etting plug)

minus (0.060

G+

.017~);gage tolerance

minus

Max. major diameter of external hread;

gage tolerance plus

Max. pitch diameter of external thread;


Min.

pitch diameter of external thread plus

/ 2 ;


Max. major diameter f external thread provided

major diametercrest width shall not beess than

0.001 in. (0.0009 in. truncation). Apply W

tolerance plus for max. size except that for

0.001 n. crestwidth apply toleranceminus.

For the 0.001 in. crest width, major diameter

is

equal to maximum major diameter

f

external

thread plus 0.216506~ minus theum of

external thread pitch diameter tolerance and

0.0017 in.

Min. pitch diameter of external thread;

gage tolerance plus

Min.

pitch diameter of internal thread;

W gage tolerance plus

Min. minor diameter of internal thread;

W


M a x . pitch diameter of internal thread;

W gage tolerance minus

Max. minor diameter of internal thread;

W gage tolerance minus

Of internal thread o be checked byage set

with ring

Nominal Size and Threaddin.

Series Designation and ToleranceClass

3

Truncated

Major

diameter

lug for GO

Full-form

4

-

5itch diameter

Truncated*

(Note 1)

6

ull-Form

and

Truncated

Setting

Plugs

Full-form

ajor

diameter

7

Plug for

N O T

GO

(LO)

8

9

Pitch diameter

Pitch diameter

(Note 2)

Ring for

GO

Mino r diameter 10

-

11

Solid Thread-SettingRings for

Snap and Indicating Gages

Pitch diameter

(Note 2)ing for

NOT GO

(HI)

12

-

13

Min or diameter

Series Designation and ToleranceClass

*

Indicated rows applyo truncated sefting plugs only.

NOTES:

(1) Truncated portion

s

required when optionalsharp root profile

n

Figs. 18,19,20,21, and 26 s used.

(2) Tolerances greater than

W

tolerance for pitch diameter are acceptable when infernal indicatingr snap gage can accomodate a

greater tolerance and whenagreed upon bysupplier and user.


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A S M E 8 3 . 2 8 3 m 2 5 7 5 5 3 2 0 1 3 6 7 7 7

A N S V A S M E B1.2-1983


GAGES AND GAG ING FOR


TABLE

6

X

GAGE TOLERANCES FOR THREAD GAGES

Threads/in.

1

80

72

64

56

48

44

40

36

32

28

27

24

20

18

16

14

13

12

11%

11

10

9

8

7

6

5

4%

4

Tolerance

on Lead, n.

(Notes 1, 3)

2

0.0002

.0002

.0002

.0002

.0002

.0002

,0002

.0002

.0003

.0003

.0003

.0003

,0003

.0003

.0003

.0003

.0003

.0003

.0003

.0003

.0003

.0003

.0004

.0004

.0004

.0004

.0004

.0004

Tolerance on

Half-Angle

of Thread,

deg. k min.

3

0 30

0 30

0 30

0 30

0 30

0 20

0 20

0 20

0 15

0 15

0 15

0 15

0 75

0

10

0 10

0 10

0 10

0

10

0

IO

0 10

0 10

0

10

0 5

0 5

0 5

0 5

0 5

0 5

Tolerance on Major

or Minor Diameters

(Note 4)

To and

Including

4 in. Diam.

4 -

0.0003

.0003

.0004

.0004

Documents

ASME B1.2.pdf