BA also is known as British Association. The British Standards Association recommends this thread form for screws smaller than ¼ inch rather than using BSW and BSF threads. This gage checks British Association external threads. BA threads are similar to Whitworth threads in terms of rounded crests and roots except that the symmetrical angles are 47 degrees and 30 minutes and the crest and root radiuses are proportionately larger. BA thread ring gages conform to S.93. Tolerances are to BS.919 Part 2 2007. BA screw thread ring gages are manufactured to nominal class. All BA thread gages are right hand only. This thread form is rarely used in the United States.
WESTport provides a complete line of BA (British Association) Thread Ring Gages. They are available in sizes from BA 0 to BA 16. Free Technical support is available from our core of engineers to assist you with any questions you may have.