On 2008-07-14, Jon Elson wrote:


Ignoramus22312 wrote:
Now that I have my lathe "working", I started looking at its condition
a little more closely. On my lathe, the cross slide is moved by a
3/4-5 ACME screw, that moves a brass nut attached to the cross slide.

There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop.

I was thinking about fixing this.

Three things come to mind.

1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom
made part to fit under the cross slide.

2) Do something clever like wax the screw and inject epoxy into the
nut to take up the slop.

3) Make a replacement part on the mill and lathe.

Has anyone dealt with this issue. Clausing wants $750 (not a typo) to
custom make this part for me.


First, measure the thickness of the thread land of the LEADSCREW at the
ends of travel and the middle. If it is much thinner in the middle, all
of the above plans will end up binding when away from the center of travel.

But, you have a workable lathe! You can cut a new screw and a new nut.
Make the screw first, as it is pretty easy to do. Then, you can cut the
nut, and test-fit with the screw until it is a snug but working fit.
Remember that the cross slide is a LEFT HAND thread! Don't ASK why I
know this so well!

If the screw actually turns out to be fine (unlikely) you can just make
a new nut. But, note that a screw with differential wear is not very
accurate to move from here to there, so if it is worn, and you don't
have a DRO, you really want to take the opportunity to replace/remake it.

I took the screw out. It has some wear, but nothing major. On a cross
slide screw, if I use a new nut, I will have modest backlash, which is
totally OK.

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