Internal threading a Whitworth cross slide nut

Dunno! It is definitely a BSW thread - I have the original prints from Emco with the call out so I am absolutely sure of the thread. It may interest you to know that the V10P uses the same cross slide thread so the NUT fits. These are made from Zamak and are very precise but difficult to find new. If you find a new nut somewhere, grab it.
 
Trash the incorrect crossfeed screw. It should be an ACME. You can buy nuts to fit a 10 tpi. screw,except they are steel. You need to slit the nut on 1 side and fit it with a screw so you can tighten the nut a little,to eliminate backlash.

The crossfeed nut really ought to be bronze,but you'd have to make a nut and thread it. Expensive to buy an acme tap. And,they are easy to break,the thread being so wide at the tip. I think the small backlash of a steel nut would be o.k. on a lathe that small. You can live with some backlash anyway,many do.
 
Or you could mould an Evanut out of Delrin / Acetal either on your existing screw (if it's evenly worn / unworn) or your new Acme screw, much easier than tapping or single-pointing and pretty durable!

Dave H. (the other one)
 
George, I actually have a Nook Acme screw and a custom-made phospho-bronze nut for it, complete with the backlash reducing feature. It works but is not as smooth as the original, nor is it as precise because the wheel graduations are not timed to the Acme thread. My lathe works but I am going to put a DRO on it soon so I don't have to deal with the lack of precision on the X-axis.

Really sucks that Emco no longer supports these fine machines. It was like pulling teeth just to get the engineered drawings for the screw and nut from them.
 
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