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AS 1721-1985
[Current]General purpose metric screw threads
Specifies requirements for single start parallel metric screw threads having the ISO basic profile for triangular screw threads, covering the size range from 1 mm diameter to 355 mm diameter inclusive. Provides for a coarse pitch series, a fine pitch series and a constant pitch series, the latter intended for use in applications for which either the coarse or fine pitch series are unsuitable. Gives information on screw thread parameters, tolerances, deviations, thread classes, designation and symbols. Appendices are included giving the basis of the tabulated values, guidelines (with examples) for calculating the limits of size of untabulated screw threads and notes on the production of screw threads.
Published: 17/05/1985
Pages: 84
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
PREFACE
1 SCOPE AND GENERAL
1.1 SCOPE
1.2 APPLICATION
1.3 REFERENCED DOCUMENTS
1.4 DEFINITIONS
1.5 SYMBOLS
1.6 VERIFICATION
2 SCREW THREAD PROFILES
2.1 SCOPE OF SECTION
2.2 BASIC PROFILE
2.3 MAXIMUM MATERIAL PROFILE
2.3.1 Maximum material profile — internal thread
2.3.2 Maximum material profile—external thread
2.4 LEAST MATERIAL PROFILE
2.5 LIMITING PROFILES
2.5.1 Limiting profiles — internal threads
2.5.2 Limiting profiles — external threads
2.6 ROOT CONTOURS
2.6.1 Internal threads
2.6.2 External threads
3 GENERAL PLAN
3.1 SCOPE OF SECTION
3.2 THREAD SERIES
3.2.1 General
3.2.2 Coarse pitch series
3.2.3 Fine pitch series
3.2.4 Constant pitch series
3.2.5 Selection of diameter/pitch combinations
3.2.5.1. Standard series
3.2.5.2 Non-standard series
3.3 BASIC DIMENSIONS
4 TOLERANCES, DEVIATIONS AND TOLERANCE CLASSES
4.1 SCOPE OF SECTION
4.2 TOLERANCE POSITIONS
4.3 FUNDAMENTAL DEVIATIONS
4.3.1 General
4.3.2 Internal threads
4.3.3 External threads
4.4 TOLERANCE GRADES
4.4.1 General
4.4.2 Pitch diameter tolerances
4.4.3 Crest diameter tolerances
4.4.3.1 Internal threads
4.4.3.2 External threads
4.4.4 Root diameter tolerances
4.4.4.1 Internal threads
4.4.4.2 External threads
4.5 TOLERANCE CLASSES
4.5.1 General
4.5.2 Disposition of tolerance classes
4.5.3 Selection of tolerance classes
4.5.3.1 General
4.5.3.2 Length of axial thread engagement
4.5.3.3 Preferred tolerance classes
4.5.3.4 Recommended assembly combinations
4.6 DEVIATIONS FOR SCREW THREADS
4.7 COATED THREADS
5 LIMITS OF SIZE FOR COMMONLY USED TOLERANCE CLASSES
5.1 SCOPE OF SECTION
5.2 LIMITS OF SIZE
6 DESIGNATION OF SCREW THREADS
6.1 SCOPE OF SECTION
6.2 COMPLETE DESIGNATION FOR INTERNAL THREADS
6.3 COMPLETE DESIGNATION FOR yEXTERNAL THREADS
6.3.1 Threads with the same tolerance class for the pitch diameter and major diameter
6.3.2 Threads with different tolerance classes for the pitch diameter and major diameter
6.4 SHORTENED DESIGNATION FOR COARSE PITCH SERIES THREADS
6.5 DESIGNATION OF A THREAD FIT
APPENDIX A
A1 SCOPE
A2 TOLERANCE GRADES
A2.1 Pitch diameter tolerances
A2.2 Tabulated values of pitch diameter tolerances
A3 CREST DIAMETER TOLERANCES
A3.1 Major diameter tolerances for external threads
A3.2 Minor diameter tolerances for internal threads
A4 FUNDAMENTAL DEVIATIONS
A4.1 External threads
A4.2 Internal threads
A5 DETERMINATION OF MINOR DIAMETER OF EXTERNAL THREADS
A5.1 Maximum minor diameter
A5.2 Minimum minor diameter
A6 LIMITS OF SIZE
A6.1 External threads
A6.2 Internal threads
A7 LENGTH OF AXIAL THREAD ENGAGEMENT
A8 STRESS AREAS FOR THREADED FASTENERS
APPENDIX B
B1 SCOPE
B2 LIMITS FOR EXTERNAL THREAD M30 × 1.25 - 5g6g
B3 LIMITS FOR INTERNAL THREAD M345 × 4 - 8G
APPENDIX C
APPENDIX D
Cited references in this standard
AS XXXX
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Content history
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