Restoring old lathes, backlash in leadscrews

[BillTodd]

Very similar to my Southbend. I sawed across the nut, down toward the mount (right-angle to bore), a thread or two from the back edge. Then drilled and tapped two small holes either side of the lead screw at the split end, so that two screws will push the split apart and reduce the backlash (I'll try to get a picture tomorrow).

Alternatively, you may be able to cut the nut completely in two and screw one part against the other (see attached pictures of my old mill's y nut). You'll have to find some way of fixing the two parts together to stop the adjuster nut turning.


[edit]

How do I measure wear on the screw - is it likely to wear or can I assume the wear is all in the nut?

Both will be worn. You should be able to detect the difference between the middle and the less-used ends of the thread. That said, the adjuster suggested above works quite well on my 72 y.o. SB 415 - it goes between tight, loose and tight over the whole travel, but the backlash is workable (perhaps ~10-20 thou at worst)