Hi Guys

Well i got a long ballscrew off eBay (53" 0.500" dia 0.500" lead 2 start) with a single nut (2 ball tracks)
However there is a fair bit of play in it; Ive not measured it but must be 3-4 thou
So as I got it for a good price i have 3 options (as I can't find who made it for a replacement nut; and i already re-loaded the nut with new balls)
option 1
Toss it
option 2
build it into a third lathe as the Z axis (I'll have to cut it down) and add some form of backlash compensator; this could be a weight on a thin wire rope hanging from a pulley
option 3
I cast a plastic nut with bronze dust mixed into the resin; I've already tried this and other than the shrinkage it will work (I had no dust in it for the test)
I can allow for the diameter shrinkage by wrapping the ball screw with teflon tape before the pour; but it's the longitudinal shrinkage that i can't dream up a way of allowing for
This nut will be following the ball nut with a spring to push the ball nut against 1 side of the threads; the ball nut will be positioned to thrust in the direction of cut; so the backlash is always compensated for (unless your backcutting)

Any ideas guys