Publishing and copyright information

The BSI copyright notice displayed in this document indicates when the document was last issued.

© The British Standards Institution 2014

Published by BSI Standards Limited 2014

ISBN 978 0 580 86558 9

The follow BSI references relate to the work on this standard:
Committee reference FME/9
Draft for comment 07/30158488 DC

Publication history

First published June 1965
Second edition, December 1966
Third edition, December 1981
Fourth edition, November 2007

Foreword

Publishing information

This part of BS 3643 is published by BSI Standards Limited, under licence from The British Standards Institution, and came into effect on 30 November 2007. It was prepared by Subcommittee SFTSE/1, Screws and fasteners technical specification committee, under the authority of Technical Committee FME/9, Nuts, bolts and accessories. A list of organizations represented on this committee can be obtained on request to its secretary.

Supersession

This part of BS 3643 supersedes BS 3643‑2:1981, which is withdrawn.

Relationship with other publications

BS 3643 consists of the following parts:

Part 1: Principles and basic data;
Part 2: Specification for selected limits of size.

Information about this document

This part of BS 3643 has been revised to bring it up to date.

Text introduced by or altered Corrigendum No. 1 is indicated in the text by tags . Minor editorial corrections are not tagged.

Hazard warnings

WARNING — Attention is drawn to the fact that, with the different screw thread forms available, there is the possibility of a mismatch, which is potentially hazardous. It is the responsibility of the designer of the end product to ensure that this possibility is reduced to a minimum. For further information on mismatches of screw thread systems see PD 6494.

Presentational conventions

The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is “shall”.

Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.

Contractual and legal considerations

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

1 Scope

This part of this BS 3643 specifies the fundamental deviations, tolerances and limits of size for the tolerance classes 4H, 5H, 6H and 7H for internal threads and 4h, 6g and 8g for external threads where appropriate for:

a coarse pitch series with the range 1 mm to 68 mm diameter;
a fine pitch series with the range 1 mm to 33 mm diameter;
a constant pitch series with the range 8 mm to 300 mm diameter.

For certain diameter/pitch combinations, the fundamental deviations, tolerances and limits of size for tolerance class 4H for internal threads and tolerance classes 6h and 4g for external threads, primarily for aerospace use, are specified in Annex A.

2 Normative references

3 Terms and definitions

4 Designation

5 Requirements

Bibliography

BS 3643-2:2007

ISO metric screw threads - Specification for selected limits of size

Current

Published:

30 Nov 2007