Actually, looking at it again I find that a simple ratio of 16:17 from the chuck to the leadscrew will give a pitch of 26.9875 tpi -probably good enough for what I suspect is a short collar. However the problem is to make that connection between the spindle and the leadscrew. It can be done, and might be worth the effort if you had a lot of them to do, and couldn't buy a tap for less than $30.
