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BS 949-4:1990

BS 949-4:1990

Current

Current

The latest, up-to-date edition.

Screwing taps Specification for metric ground thread taps: manufacturing tolerances

Available format(s)

Hardcopy , PDF

Language(s)

English

Published date

29-06-1990

Publisher

British Standards Institution

National foreword
Brief history
Text of EN22 857
Specification
1. Scope and field of application
2. References
3. Basic data
3.1 Thread profile of nuts
3.2 Thread profile of tap
3.3 Tolerance classes of taps
3.4 Calculation of tap thread dimensions of classes
     1, 2 and 3
4. Manufacturing tolerances on tap threads
4.1 Major diameter d
4.2 Pitch diameter d2
4.3 Minor diameter of tap d1
4.4 Tolerances on the half-angle alpha/2 of thread
4.5 Cumulative pitch error Tp over any number of
     threads
5. Designation and marking of taps
6. Example of calculation of the dimensions of the
     threaded portion of a tap
Annexes
A. Ground thread taps for ISO metric threads of
     coarse pitch
B. Ground thread taps for ISO metric threads of
     fine pitch
National appendix A
National appendix B
Cooperating organizations

Manufacturing tolerances on the threaded portion of taps for producing ISO metric threads of tolerance classes 4H to 8H and 4G to 6G. Valid for short taps specified in ISO/R 529 as well as any other kind of ground thread taps with the same diameters and pitches.

This International Standard specifies the manufacturing tolerances on the threaded portion of taps for producing the ISO metric threads of tolerance classes 4H to 8H and 4G to 6G as defined in ISO/R 965-I to III (excluding, consequently, classes 7G and 8G considered as usually produced with ground thread taps).

It is valid for the short taps specified in ISO/R 529 as well as for any other kind of ground thread taps with the same diameters and pitches.

The internal threads produced with those taps are conventionally designated by the simplified denomination of “nut?? in agreement with the word used in ISO/R 965 for the general designation of all internal threads.

Annex A and Annex B give, for all threads with coarse and fine pitches, the manufacturing tolerances on the threaded position of taps for the following classes of nuts:

4H and 5H − 6H − 7H and 8H

and 4G and 5G − 6G

Committee
W/-
DevelopmentNote
Reviewed and confirmed by BSI, March, 2004. (11/2004) Also numbered as EN 22857 and ISO 2857 Supersedes 85/78210 DC and BS 949-1(1976) (10/2005)
DocumentType
Standard
Pages
28
PublisherName
British Standards Institution
Status
Current

Standards Relationship
EN 22857:1989 Identical

ISO 2283:2000 Long shank taps with nominal diameters from M3 to M24 and 1/8 in to 1 in — Reduced shank taps
BS 949-1:1976 Screwing taps Specification for taps for ISO metric threads
BS 3643-1:1981 ISO metric screw threads Principles and basic data
ISO 2284:2017 Hand taps for parallel and taper pipe threads — General dimensions and marking
BS 5346:1976 Specification. ISO metric trapezoidal screw threads
ISO 529:2017 Short machine taps and hand taps
BS 949-3:1982 Screwing taps Specification for taps for pipe threads (G series, R<sub>p</sub> series and R<sub>c</sub> series)
BS 949-5:1990 Screwing taps Nomenclature and terminology

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