reducing backlash

[Simon GearyParticipant @simongeary74381]

Is this a daft idea ?, my cross slide has the thread cut into the casting at the front , it is quite badly worn as you might expect from a 100 year old lathe , I wondered if I had another set of threads at the back end of the casting that were either externally threaded . or held in place by a grub screw by pulling back against the front thread would it remove the backlash .or would adding the other set of threads just cause the screw to lock up

[Simon GearyParticipant @simongeary74381]

[Speedy Builder5Participant @speedybuilder5]

I suspect that the wear along the cross slide screw is uneven, so trying to compensate with an opposing screw would 'fail'. Could you bush the thread in the casting and make a new cross slide screw/ threaded nut, or make the thread a larger diameter ?
You would loose accuracy, but you could have a fairly stiff spring on the end of the slide screw to 'take up slack'.
BobH

[AjohnwParticipant @ajohnw51620]

That sort of arrangement is usually called jam nuts. 2 nuts so that their distance can be spaced apart to set the back play.

Not that popular as people tend to account for backlash when they work and zero might be tough to achieve.

John

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[David JuppParticipant @davidjupp51506]

My old Smart & Brown cross slide has such an arrangement. As pointed out by BobH the uneven wear along the feedscrew does tend to limit how useful this feature is. At best it can minimise backlash at the less worn ends of the screw, still leaves it sloppy for much of the travel.

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