BS 919-2:2007

Foreword
1 Scope
2 Normative references
3 Terms and definitions and symbols
4 Design
5 Disposition of gauge tolerance zones
6 Gauges for internal screw threads
7 Gauges for external screw threads and
  their setting plugs
8 Marking
Annexes
Annex A (informative) - Function and method of
                        use of various gauge types
Annex B (informative) - Conventional illustration
                        of tolerance zones
Annex C (informative) - Effective diameter equivalent
                        of pitch and angle errors
Annex D (normative) - Thread form of NOT GO effective
                      diameter gauges
Annex E (informative) - Hardness
Bibliography

Describes requirements for the following gauges intended for checking screw threads in the regular series, such as BS Whit., BS Fine, B.A., BSC and BS Conduit.

This Part of BS 919 specifies requirements for the following gauges intended for checking screw threads in the regular series, such as BS Whit., BS Fine, B.A., BSC and BS Conduit.

a) Screw gauges for general and reference use:

1. solid (non-adjustable) screw plug gauges, GO and NOT GO;
2. solid and adjustable GO screw ring gauges;
3. adjustable thread calliper gauges, GO and NOT GO.

NOTE NOT GO effective diameter ring gauges are also included since they have certain limited applications. In principle, however, their use is not recommended.

b) Plain plug gauges and plain calliper gauges for the crests of threads.

NOTE Provision is made in the standard for both GO and NOT GO plain gauges, but GO plain gauges are normally required only in the case of threads where the corresponding GO screw gauges do not control the maximum metal condition at the crests of the threads of the product.

c) Setting plugs for adjustable screw ring and thread calliper gauges, GO and NOT GO.

This standard may be applied also to gauges for any screw threads of Whitworth form, but not to gauges for Acme, buttress or round threads.

Annex A provides guidance on the various types of gauges.

Information relating to the effective diameter equivalent of pitch and angle errors and to the thread form of NOT GO effective diameter gauges is given in Annex B, Annex C and Annex D.

No requirements are specified for the materials for gauges, but guidance on the hardness of gauges is given in Annex E.