My main activity is restoring vintage motorcycles so having some clean up taps and dies is very useful. I have to prioritise on spending to afford some of the things I canít make as it it is not a cheap hobby, the answer for me was to make them.
So far I have 5/16 and 3/8 BSCY in 26 TPI made of oil hardening tool steel and they have even been used to make new items sometimes in stainless as the thread depth is only .0205. the dies are made with the taps, anything larger can be screwcut, and I have chasers for that.
I know some will view this thread system as archaic but the motorcycle I am working on is 97 years old and apart from an engine has more in common with a bicycle (you canít change history).
Having said that some of these threads were still in use into the sixties until UNF became more common and then of course Metric.
The main reason for posting is to show it is fairly easy to make them especially if you encounter an oddball size.