[BrassBuilder]

Hey All,
Sure hope someone can help me again. I have a RM1204 ballscrew from linearmotionbearings2008 on ebay (Chai). The nut on the end of the ballscrew will not stay tight. I've tried to turn the bearing block around, but on the other side, the nut sits in an indentation in the bearing block and I cannot get the set screw tightened.

When the ballscrew starts turning, the nut comes loose and then the ballscrew starts sliding back and forth in the mount (resulting in GOBS of backlash!)

I've tried to tighten the nut down fairly snug and I left it so it just made contact with the bearing. I also put a washer between the bearing block and the nut...it all ends up being the same. The nut will eventually work its way loose.

I've tried to tighten the set screw as tight as I can get it without having the allen wrench jump.

Sorry for the crappy pictures, but it is the best I could get.

I'm contemplating drilling out the set screw hole and putting the next size bigger in. Maybe I can tighten it just a little more.

Any other ideas?

Thanks

Mike

[hoss2006]

try some blue 242 threadlocking loctite or a second jam nut or both.
Hoss

[BrassBuilder]

try some blue 242 threadlocking loctite or a second jam nut or both.
Hoss

Thanks Hoss! I should have thought of that. I even have a second nut around here....somewhere....

I got my ballscrews dialed in too. Got the cross slide wired up tonite and got it dialed in pretty close...at least until my ballscrew started moving back and forth.

Mike

[BrassBuilder]

Got it double nutted....still have about .001 play in it....if I tighten it anymore, I can barely turn it by hand and even then, I still have a little movement in it.

I'll just adjust my backlash in Mach3 for .001.

Mike

[eartaker]

That would be a case of ****ty bearings... Look at changing them out.

[mrcodewiz]

The set screws that come with his lock nuts are awful. Mine were pretty well rounded before I ever touched them. I replaced them all with new set screws and they are much better now.

[diecutter]

Got it double nutted....still have about .001 play in it....if I tighten it anymore, I can barely turn it by hand and even then, I still have a little movement in it.

I'll just adjust my backlash in Mach3 for .001.

Mike

To double nut properly, first tighten the original nut until there is no play and no binding. Then put a wrench on this first nut to prevent it from moving (and also make sure the shaft stays stationary) and tighten the second "jamb nut" securely against it. The second nut should not change the adjustment if the first nut and shaft remain stationary. Hope this helps.:cheers:

[gd.marsh]

I have read some complaints on the zone about these particular bearing blocks being a source of backlash.

Tightening the nuts down will clamp the bearings tighter to each other, but if there is clearance between the bearings & the block holding them, you'll still get some end play.

This should be correctable with the a shim of the proper thickness to fill the gap between the outer race of the bearings & the block.

[BrassBuilder]

I have read some complaints on the zone about these particular bearing blocks being a source of backlash.

Tightening the nuts down will clamp the bearings tighter to each other, but if there is clearance between the bearings & the block holding them, you'll still get some end play.

This should be correctable with the a shim of the proper thickness to fill the gap between the outer race of the bearings & the block.

I think I see what you are saying on this....I'll have to take a closer look at it.

I took a look to see what McMaster-Carr had and I found some new bearings and thrust bearings that should work in the block. I was going to use a set of thrust bearings on each side of the block with the bearings in between. But I may still have to put a shim in there of some sort....

I'll update this as soon as I get the bearings.

Mike