The Amal book only gives the information that you already know. It's a very fine thread for the diameter involved. It's not ME. I'm not an engineer, but since there's only 5 degree difference between the thread angles BSF and BSC, could you not cut one and try it and maybe alter it if it's the wrong one? Ron
Hi, I had an adapter made for my cabby by a machinist,I am certain if take the bits to a machine shop they will be able to manufacture the part with correct threads as I think the threads are cut on a lathe.
Cheers Ian