Ran ballnut off ballscrew on the knee of mill

[Toolguy]

I have a CNC mill with X and Y handwheels. I never use them, just the MPG handwheel on the control panel. It's much easier and more precise, too.

[The Metal Butcher]

That's a neat design. I was going to do the same thing potentially to my Daewoo since it came with a fixed ballscrew and rotating ballnut. All I need to do is put some bearings and a motor on the ballscrew, and I lock for the ballnut and one axis is done in so far as a CNC conversion. Still could be run manual as well.

[tom_d]

Aren't the larger balls going to roll against the smaller ones just the same??

JL......

Small ones will be in contact with the larger, and rotate in an opposite direction like meshed gear teeth. They rotate in an opposite direction but do not contact the screw and nut simultaneously so they do not cause any friction.

[oxford]

You all owe me an apology SOFORT!!!!

Sorry that your nuts are getting twisted?

[Doozer]

Small ones will be in contact with the larger, and rotate in an opposite direction like meshed gear teeth. They rotate in an opposite direction but do not contact the screw and nut simultaneously so they do not cause any friction.

This is a great summation of the reason why every other ball is smaller.
I love to learn.
Thanks.
Ever watch the rollers on s garage door track ?
See sometimes they roll forwards and sometime
they roll backwards, depending on how the door
is pressuring the track ? This makes me think
of that.

---D

[garyhlucas]

I built walls that could be raised on the side of a greenhouse for a customer. The walls were between 240 and 350 feet wide and opened vertically about 8 feet. I used Harken ball bearing traveler slides that use Torlon plastic balls against hardcoat anodized aluminum. It works, and has for over 20 years now, but not as well as I wanted. The reason is ball stacking. When the wind rattles the walls the balls fall downwards and pack tight against the races and each other. So starting the wall moving is sometimes difficult and noisy. Simple fix would be large ball/small ball but I never found a source for smaller Torlon balls.

[Rich Carlstedt]

Whats the name of this secret mill ?
So what you are saying is that it is Operator Error and not lost balls ?
glad you are over Covid

Rich

[Black Forest]

What I am saying is it is/was operator ignorance. But I still blame you guys!

[Black Forest]

Now I know why the man from the factory that I talked to told me it was impossible for the ballnut to run off the screw. He did say if it was original equipment then what I described could not happen. On Tuesday I will call him back and tell him he of course was right. But in my defense it could have happened the way I thought if it wasn't built the way it is built. Have any of you all ever seen a cranking mechanism like what I described that is actually on the machine?