I just read this today and thought I would share it here, since it is an issue that's raised regularly when people want to replace the very odd-sized cross-slide nuts on the viceroy machines. Basically, the process involves using the screw and a heat gun to mould a new nut from acetal. The result is a perfectly-formed low-friction nut with zero backlash and a VERY low wear-rate. No harm is done to the machine and the cost is next to nothing.
Read about it in this thread here:
https://bbs.homeshopmachinist.net/showthread.php?t=43645
Site Admin
For those of you (including myself) who don't know what Acetal is - it's also known as Delrin:
https://en.wikipedia.org/wiki/Polyoxymethylene_plastic
https://en.wikipedia.org/wiki/Polyoxymethylene_plastic