Hi Folks,
Happy New Year to All.
Funny this thread has come up, as I've had a similar conundrum regarding modifying the cross slide leadscrew on my Son's Bantam 800.
To start with the details, thread is 9/16"dia x 5 x 2 start lh acme, i.e. 200 thou divs on dial.
E-bayed for bits, they price ranged from ridiculous to insane, scrubbed that.
The nut was worn as was the leadscrew (reason for replacing
http://madmodder.net/Smileys/default/doh-45.gif).
To cut a very long story short, we bought a 5/8" x 10 lh acme tap, some internal and external acme 10 tips, and left and right toolholders, also a 1/2" x 10 rh acme tap for a topslide nut replacement.
I also had to grind a 3/16" woodruff cutter for the splined section, just doing that incurred making a grinding jigs for the Clarkson.
I used EN16T 5/8" bar for the cross slide screw.
I should have added that in going this route I've halved the dial readout, so what is dialled is what's taken off, far better for my Son anyway, although I'm not having a pop at anyone, this is a tool to be used, not an artefact.
Pics below tell the tale....