So far I have only found BSW and metric and it is very plain to see the new ones are metric and the old ones BSW
The lathe has a leather gear that conects the headstock gears to the change gears and also changet the DP from ???? to DP14. This leather gear is obvoisly some kind of savety gear but the inside has stripped the key stops it from moving more than 180 deg.
So I need a new gear but not metal as it has to be able to break rather than break the machine.
So making a delrin gear to replace the leather one.

and 20 cuts later

ANd this pic shows to new gear meshing with the gear it is to replace.

The gear tooth shape is not perfect I think I was cutting a small part of a mm high ???dont know how to center more accurately up and down.
Gerhard