Leadscrew backlash reduction

[Bob Engelhardt]

Crawling around the web, I found this:



It's a product, but I'm thinking that an in-machine nut could be modified to be like it. A slit and an adjusting screw, what could be easier?

Thoughts?

[Paul Alciatore]

Backlash reducer? Sure is!

Wear increase? Also YES!

I think that Evan's Evanut was the best way I have seen.



And is that an acme screw or a ball screw?

[chipmaker4130]

My Sheldon came with something sort of similar on the cross-slide. It does work, but depending on the material used it can wear back to where you started pretty quickly.

[Bob Engelhardt]

Backlash reducer? Sure is!

Wear increase? Also YES!

I think that Evan's Evanut was the best way I have seen.



And is that an acme screw or a ball screw?

If there still was some backlash,even at the tight ends, there wouldn't be any increased wear, would there?

Acme.

A new acetal nut would mean starting from scratch.

[Doozer]

If there still was some backlash,even at the tight ends, there wouldn't be any increased wear, would there?

.

When you split the nut you cut the bearing surface area in half.
Hence twice the wear. Splitting the nut is a bad idea,
Nothing wrong with backlash. If you think there is, seek help.

-D

[chipmaker4130]

The Sheldon implementation is a little better in that it uses a full-size nut, then adds a smaller adjustable section. I haven't adjusted it in the last 15 years. Yeah, Doozer, backlash is a fact of life, but the less the better.

[wierdscience]

Crawling around the web, I found this:

Why did they use a tapped Bronze nut on a ballscrew???

[Doozer]

Backlash means it is wearing in
not wearing out. (Usually).

---Doozer

[Doozer]

Why did they use a tapped Bronze nut on a ballscrew???

Circular form tap.
Coil thread is what it is called.
Used in rebar nuts for concrete forms.

-D

[J Tiers]

Can't see it for a leadscrew, where's the problem that is being solved?

For a FEEDscrew, OK, it does eliminate an extra nuisance for certain operations, if the backlash is "effectively" zero afterward.

Problem is, the wear isn't even, so the nut cannot actually eliminate the issue. Only in some spots. The rest either still have backlash, or are too tight, depending.

[wierdscience]

Circular form tap.
Coil thread is what it is called.
Used in rebar nuts for concrete forms.

-D

That's not coil thread

[Bob Engelhardt]

When you split the nut you cut the bearing surface area in half.
Hence twice the wear. Splitting the nut is a bad idea,
Nothing wrong with backlash. If you think there is, seek help.

-D

Oh yeah - I see that. Thanks.

I used to think "nothing wrong with backlash", e.g., in the context of cross feed screw, where you just always approach the cut in the same direction. But the other day I was fly cutting on my (loose) mill and I got some terrible dancing when the cut was climbing. It's very possible that my technique was lacking, but it seemed like less backlash would help.

[Doozer]

That's not coil thread

No ? ? ? ? ?
What makes you think not ?

-D

[Peter.]

Circular form tap.
Coil thread is what it is called.
Used in rebar nuts for concrete forms.

-D

Those formwork nuts over here are used as-cast, the threads are not cut into them nor even cleaned up with a tap.

[skunkworks]

Properly adjusted high quality ball screw nut - there is no backlash...

sam