Measure once, cut twice

Aug 06, 2011 5 Replies

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Mark Rand 14 years ago

I've made a new set of anti-backlash leadscrew nuts for the Beaver milling machine table.

A fixed nut and an adjustable anti-backlash nut.

The fixed nut is 2" long and 1 5/8" diameter . It has a 1" 5tpi ACME thread for the leadscrew and a 1 3/8" 20tpi thread for the adjusting nut.

I machined the bores, cut the threads to fit the leadscrew and adjusting nut all at one setting, verified the fits to be as near perfect as I could get and then mounted it on a mandrel to trim the OD to the required 1 5/8" diameter to be a snug fit in the housing.

Take 100 thou off the diameter, measure 1.724. Take 101 thou of the diameter to reach final size...

Oh Schidt. I now have 1.623" and a sloppy fit where it should be a snug fit.

Time to start again...

Mark Rand RTFM

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Jim Wilkins 14 years ago

If it's solid bronze maybe you could just coat it with hard solder.

jsw

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Emimec 14 years ago

What about a knurling it........ Bob

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John H 14 years ago

Reduce the diameter some more, say 60 or 70 thou and shrink on a bronze sleeve. Turn down to correct size.

John H

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John S 14 years ago

What was you expecting ?1.724 - 101 =3D 1.623

Dumkoff.

John S.

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Mark Rand 14 years ago

The Hardinge seems to take off pretty well exactly what I tell it to, but it isn't very good at pointing out my arithmetic mistakes before the cut. :-(

I'm going to make another nut because bushing this one isn't practical (it's cast iron and I don't want to loose too much meat off it). Loctite isn't preferred, because I _might_ want to take it apart again.

I can use the undersized one to lap out the variation in the leadscrew threads, 3-4 thou worst case. Once I've mapped them out.

Mark Rand RTFM

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