I seem to recall that 0BA (British Association size 0) has a thread pitch of 25.4 per inch or 1 mm. It also reminds me of British Standard Fine threads, and a newly-arrived colleague who marked all his toolkit with his initials - BSF. As we only used BA threads at that stage there was some confusion.
To add to the fun, I was working on silicon rectifier stacks whose heatsinks were held together with 2BA threaded rods, the nuts for which had a 1BA head.
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On 30 Mar 2018, at 05:46, Steve in Okinawa <
sfab43@...> wrote:
Thread pitch is easy with metric because there is only one standard pitch for a given diameter, no SAE/UNC/UNF or (God forbid) Whitworth. And as far as I can tell, metric country pipe threads are in inches.
Steve Fabricant
