X2 Ballscrews ??s

[maxboostbusa]

Im fixing to get ready for the cnc conversion on my x2 and was wondering what the majority of you are using for your nut setup. 1 regular ballnut, 2 regular ballnuts spring loaded to eliminate backlash, or a preloaded ballnut. I was going to go with 2 ballnuts loaded with belleville washers for 0 backlash but after reading some on this I dont think I can afford to loose a couple inches of travel like it seems to do with this setup. Thanks for all help.

[maxboostbusa]

Anybody??

[The Blight]

I'm using one ballnut which you can say is preloaded. I had to remove a big piece of the sadle to fit it in there, but it works perfectly. I have measured backlas down to less then 0.01mm (0.0004"). The problem with preloaded nuts is that they wear out, and you have no way of compansating for this (unless you preload it again. I can simply just tighten a srew, and it's all good again). I think you can fit two nuts on all axes with some work without loosing travel. The hardest part will be the Y axis, but if you place the nuts far enough down below the sadle, you will have plenty of space.

Do you have access to a cad program? If so, you could draw up the machine and do the testing there. Thats how I made the parts for my machine (X2).

[cnczoner]

Originally Posted by The Blight ... The problem with preloaded nuts is that they wear out, and you have no way of compansating for this (unless you preload it again. I can simply just tighten a srew, and it's all good again)...

Curious -- how long (operating hours, I guess) before noticeable wear occurs? I'm just looking for a ballpark answer to see if I would be replacing balls every month, year, decade...???

Thanks,
-Neil.

[The Blight]

That I don't know, but I guess it's not much on a machine like the X2. I have only tightened (preloaded) the screw on the casing once, and it still has less then 0.0004" (0.01mm) of backlash after a year or so. And I use the machine quite a bit.

[Rodm1954]

I only had to tighten the pre-load on the double nuts once as well but I think that is the issue. They need adjusting after the initial run in so if you buy pre-loaded ballnuts then maybe they need repacking after the run in period. I had a single pre-loaded nut on Y and ended up making it a double nut as it developed some backlash. They are rolled ballscrews.