7x12 Mini Lathe Anti-Backlash nut.

[Deviant]

Has anyone made one of these, or know of a website that provides them?

I've tore the machine down to the last screw and reassembled with fresh oil/grease and tighten all the grub screws and handles. The carriage is very solid now.

With two problems.

The cross slide handle has about half a turn play. I don't think there is any more adjustment that I can do with the base hardware to improve this. I think the next option is to mount some type of anti backlash nut.

The compound has a little play, but not quite as much. I'd like to get these down to bare minimal.

I'm not sure what the best solution would be. Mill/thread a piece of delrin/cutting board? Mill/thread a peice of brass slot it and add an expansion grub screw?

Another option would be use some type of ball screw, but I think that would involve making a new saddle.

Second problem. The half nuts have a small amount of play. I'm going to try to adjust this out. But I'm not sure what a normal amount of play would be.

I'm not even sure if this is an issue, as you don't normally have a lot of forward/back movement with halfnuts.

Any info/help would be great.

Thanks

[Oldmanandhistoy]

Wow half a turn of the handle; that’s not good. I have close to 0.025mm (0.000984249”) of backlash on mine. Have you see this http://www.mini-lathe.com/Mini_lathe....htm#xbacklash .

John

[Deviant]

No I hadn't seen that area of the website.

I crawled all over the site before I bought the lathe and never saw it. I'll give the adjustments a go. Hopefully the backlash will clean up. It it's current state, it is highly frustrating to deal with.

Thanks for the reply.


*edit*

I just went out and attempted to move the cross slide back and forth. I have no detectable play. I'm going to put a indicator on it, for a better view.

I have roughly 1/4 turn in the handle. If I'm doing the math correctly, that's .2mm. ((8*0.025mm)).

Going to try the instructions now.

[John Kelly]

I am converting an 11 x 26 lathe to CNC and am concerned about excessive backlash so I made the antibacklash nut shown in the pictures.
The block and nut are made from 420 SS and the screw a LH 7/16 x 20 made from a piece of drill rod. The spring was purchased fron MSC # 36099G. The screw is a LH 7/16 x 20. I have not tested it as of yet but I feel confident that it will work.

regards,

John Kelly

[Oldmanandhistoy]

Originally Posted by John Kelly I am converting an 11 x 26 lathe to CNC and am concerned about excessive backlash so I made the antibacklash nut shown in the pictures. The block and nut are made from 420 SS and the screw a LH 7/16 x 20 made from a piece of drill rod. The spring was purchased fron MSC # 36099G. The screw is a LH 7/16 x 20. I have not tested it as of yet but I feel confident that it will work. regards, John Kelly

Hi,

Nice job; did you do any calculations to workout what spring to use?

Would you mind posting here after you have tested it?

Regards,

John

[John Kelly]

I have purchased a few different springs and the one that feels the best so far is about an 8 lb. spring. I will keep all posted as I test the system, my biggest concern is going to be wear on the nuts but time will tell.

regards,

John Kelly

[Deviant]

I adjusted the 3 screws and took out 99% of the backlash. I never realized that those screws were for that purpose.

The problem now is that the screw is very hard to turn. I'll have to keep messing with it til I get a happy medium.

I didn't see any type of adjustment for the compound. It has a little bit of backlash, but nowhere near that was on the cross slide.

Thanks for the link. It helped alot.

[Deviant]

Played in the shop for a bit tonight.

Was able to turn down a piece with .0001mm of what I was looking for. It's like a brand new toy. *grins*

Played around with the screws for a while, finally found a good setting that took away the backlash and still allowed me to turn it with very little effort.