Hello Lee,

There have been discussions elsewhere on the forum in the past about using Delrin as Tee nut material to replace worn units.

It can be simply moulded around this stumpy thread as two halves which will heat bond on the edges to make a whole cylinder which you then machine and fit to the extension.

The only precaution you need to take is to make sure you don't extend the 'nut' into the thread run out area on the fixing side otherwise you will have some difficulty unscrewing it when cold. A spray of WD 40 on the thread should help as a mould release agent.

Regards

Brian.

To answer one of the questions asked by the OP; the tpi for a given size of Acme thread can be whatever the designer chooses. There are recommendations, for 3/8" it is 12tpi, but the 'standards' are not hard and fast.

It's not difficult to make a set of taps, if I can do it I'm sure everybody else can, these are 1/2" diameter, 8tpi, square thread serial taps:

Andrew