Quote Originally Posted by David TS View Post
M6 coarse is 60 degree thread form, 0BA is 47.5 degree thread form.
All depends on how much torque is put on the nut/thread.

If memory serves me correctly 2BA will fit 3/16 B.S.F.

---------- Post added at 12:51 AM ---------- Previous post was at 12:43 AM ----------

A story that I heard was that BSW dropped a spanner size on all it's threads, making it the same as B.S.F. spanner sizes, during WW2 in order to save steel. How true and how much steel was saved I don't know but it does give one explanation as to why one encounters 2 sizes of B.S.W. nuts/bolts.
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