BS 919-1:2007

Foreword
1 Scope
2 Normative references
3 Terms and definitions and symbols
4 Design
5 Tolerances and thread forms
6 Marking
Annexes
Annex A (informative) - Verifying conformity with BS 1580
Annex B (informative) - Conventional illustration of
                        tolerance zones
Annex C (informative) - Effective diameter equivalent of
                        pitch and angle errors
Annex D (informative) - A system of gauging for screw threads
                        before and after coating
Annex E (informative) - Setting to size of adjustable screw
                        ring gauges
Annex F (informative) - Comparison between the designations
                        of British and American gauges
Annex G (informative) - Tolerances for major, effective and
                        minor diameters and flank angle and pitch
Annex H (informative) - Hardness
Bibliography

Describes requirements for the following types of gauges intended for use in the checking of products with unified screw threads for conformity with BS 1580.

This part of BS 919 specifies requirements for the following types of gauges intended for use in the checking of products with unified screw threads for conformity with BS 1580.

1. Screw gauges:
   1. solid screw plug gauges, GO and NOT GO;
   2. solid screw ring gauges, GO and NOT GO;
   3. adjustable screw ring gauges, GO and NOT GO;
   4. adjustable screw calliper gauges GO and NOT GO.
2. Setting plugs for adjustable ring gauges and for calliper gauges, GO and NOT GO:
   1. double length;
   2. single length.
3. Screw check plugs for solid screw ring gauges, GO and NOT GO.
4. Plug gauges and calliper gauges for the crest diameters of product threads, GO and NOT GO.

Annex A gives information about the various types of gauges covered by BS 919. Annex B explains the conventional method for showing the tolerance zones of gauges. Guidance on the calculation of the effective diameter equivalent of pitch and angle errors is given in Annex C. Annex D recommends a method for gauging screw threads before and after coating. Notes on the setting to size of adjustable screw ring gauges are presented in Annex E, while Annex F presents a comparison of British and American screw thread terminology. Annex G discusses the tolerances for major, effective and minor diameters and flank angle and pitch permitted by BS 1580. Guidance on the hardness of gauges is given in Annex H.