Restoring old lathes, backlash in leadscrews

[ptjw7uk]

Have you considered casting a nut thread using moglice not any idea how much it costs but an idea.
http://www.moglice.com/articles/repl...tethebook.html
(see figure 14)
I suspect you would need a new length of threaded rod to replace the screw.


Peter

[irving2008]

Have you considered casting a nut thread using moglice not any idea how much it costs but an idea.
http://www.moglice.com/articles/repl...tethebook.html
(see figure 14)
I suspect you would need a new length of threaded rod to replace the screw.


Peter

Peter, I've looked at this stuff before, but its hard to get in small quantites. I did wonder about using plastic epoxy metal and packing the nuts, oiling the screw, screwing it in and leave to set... might contain the backlash for a while - worth a try maybe

[irving2008]

Took the other leadscrew (cross-slide) off today. Its identical to the topslide one, although at some time in the past somone has lopped 7/16" off the brass bearing and inserted a (poorly machined) micrometer dial and attempted to solder a pointer (now missing) to the brass sleeve.

I now have everything ordered I need to do this except some 7/16-10 LH leadscrew, wanted to find a UK source as the US source is 10 days shipping and was hoping to make a start this weekend. Kingston Engineering don't go down to 7/16, their smallest is 1/2 but this won't fit through the holes in the slides :sad:

Anyone know of a UK source for 400mm or so 7/16-10 leadscrew? I wanted to go metric but although MD have 10x2D LH at 99p/100mm I cant get a 10x2D LH tap at reasonable cost unless someone has one they can lend me...

[John S]

Order a bit extra and flute it and get it cyanide hardened and use that for a tap.

.

[irving2008]

Order a bit extra and flute it and get it cyanide hardened and use that for a tap.

.

Interesting, I assume that would be OK for brass, being a lot softer (I dont suppose it would tap brass without hardening?)

Where and how much roughly?

[irving2008]

Hmmm..got a couple of 'approximate' quotes for hardening a 150mm length of 10mm - £80! and that depends on the actual steel used.

Maybe I need to learn how to do hardening at home... I have the book...

[John S]

Hmmm..got a couple of 'approximate' quotes for hardening a 150mm length of 10mm - £80! and that depends on the actual steel used.

Maybe I need to learn how to do hardening at home... I have the book...

Not easily done just by the heating and quenching as the screw will almost certainly be low carbon steel.
The only easy way to do this is by pack hardening in something like Kasenite which makes a mess of fine details like a tap, hence the reference to molten cyanide.

If you fancy going this route, buy an extra 150 to 200 mm length, send it up and I'll flute it and get it hardened in with the next batch of gear that goes over.
I'll make two, you get one back, I keep one for payment.