[tauscnc]

Are ballscrews very gritty?

I find if I turn the screw counter-clockwise it's pretty smooth. However when I change direction (clockwise) it is tough. It like they are getting stuck and I feel like I am going to break them. They loosen but get stuck again.

So far I don't see the luxary of ballscrews or are these Nook ones just cheap? They list thompson on the website but nook is what I have. The leadscrew on the Z axis is silk.

There has to be some grease they need...

UPDATE:
I called Nook and they said to use E-900 lub. The ballscrew is a standard roll screw and the info on the nut is here (SBN10325)http://nookindustries.com/ball/BallSRTInfo.cfm?id=15

taus

[ckirchen]

Tuaseef,

When I ordered my ballscrews and ballnuts from Rockford, they were extremely gritty. I dismantled the nuts and sprayed them with WD-40 over a white paper towel to see what was in there. Lot's of dirt, some grease, and even a few full chips came out.

I ordered another ballnut from Thompson a while later and it was dirty as well. Not as bad as the Rockford, but still in need of a good cleaning.

My advice: before you install a ballnut, take it apart and clean it thoroughly. They’re not hard to put back together (http://industrialhobbies.com/howto/p...ed_ballnut.htm). And, wipe down the entire length of the screw while you're at it.

Chris Kirchen

[ballendo]

Taus,

Yes, ballscrews designed for use where their reduced friction and increased efficiency are the main concern; are often less than ideal when pressed into use for precision positioning. IOW, there are ballscrews that really weren't meant to be used the way we use them in DIY-CNC. And the "actuator grade" that are likely used by K2--and most others at teh low end of CNC, really WILL be better if you do a bit of work to them.

I'd suggest following the advice Jeff D gave about disassembling each one and cleaning with a wire brush and or scotchbrite pads.

BTW, if you spread out a sleeping bag, then put a WHITE sheet over it, then SIT down in the MIDDLE of it, you'll likely not lose any balls when you disassemble.

Roland Friestad had an article about assembling ballnuts to the screws in HSM magazine. The idea you used with vaseline is pretty much what we all do, just using white lithium or --in my case-- Krytox grease (Grainger's has it.)

Point is, even tho you don' wanna. IMO you'll be glad--in the long run-- if you DO take these apart and clean 'em up...

The factory guy who said .008 is a clue; this is DEFINITELY NOT a motion control grade screw/nut.

You asked where to get balls? Bal-tec in Los Angeles, CA, USA is an EXCELLENT source. (I tend to use oversize balls in a single cheap ballnut with the low grade rolled screws; and it works well. there is a bit of time where the balls are "running in"; then that goes away and things work well.

Hope this helps,

Ballendo

Are ballscrews very gritty?

I find if I turn the screw counter-clockwise it's pretty smooth. However when I change direction (clockwise) it is tough. It like they are getting stuck and I feel like I am going to break them. They loosen but get stuck again.

So far I don't see the luxary of ballscrews or are these Nook ones just cheap? They list thompson on the website but nook is what I have. The leadscrew on the Z axis is silk.

There has to be some grease they need...

UPDATE:
I called Nook and they said to use E-900 lub. The ballscrew is a standard roll screw and the info on the nut is here (SBN10325)http://nookindustries.com/ball/BallSRTInfo.cfm?id=15

taus

[ballendo]

Forgot to add that since you have a lathe; make yourself a short rod the same diameter as the root of the ballscrew. This is used when you reload the nut (when you buy a ballnut by itself it comes with a shart cardboard tube of this diameter inside to keep the balls from falling out. You then put the nut against the end of the screw and turn the nut onto the screw--and off the cardboard tube...

Another item you can make which helps immensely is a set of two collars that fit the OD of the ballscrew and are milled (for square body ballnuts) or turned(for round body ballnuts) to locate the ballnut exactly concentric to the ballscrew.

You put the empty ballnut on the screw; add these collars on each end of it, and now the ballscrew is in the center. This makes adding the balls REALLY EASY. Worth the time to make IMO.

Ballendo

[DieGuy]

Forgot to add that since you have a lathe; make yourself a short rod the same diameter as the root of the ballscrew. This is used when you reload the nut (when you buy a ballnut by itself it comes with a shart cardboard tube of this diameter inside to keep the balls from falling out. You then put the nut against the end of the screw and turn the nut onto the screw--and off the cardboard tube...

Another item you can make which helps immensely is a set of two collars that fit the OD of the ballscrew and are milled (for square body ballnuts) or turned(for round body ballnuts) to locate the ballnut exactly concentric to the ballscrew.

You put the empty ballnut on the screw; add these collars on each end of it, and now the ballscrew is in the center. This makes adding the balls REALLY EASY. Worth the time to make IMO.

Ballendo

Those are great recomendations! that keeps the balls from getting out on top of the thread!