ballscrew to stepper shaft alignment

**dazp1976** · 18-09-2021

+1...

You have a machine that's running so why not make some custom parts and beef it up!?.
Make some bearing carriers that are 1 inch thick to house 2 AC bearings back to back to replace those BK things.
I did that on my mill using 7201-2rs (1605 ballscrews). I'll never go back to niether standard or thrust types ever again!.

**marbles** · 18-09-2021

Originally Posted by dazp1976

+1...

You have a machine that's running so why not make some custom parts and beef it up!?.
Make some bearing carriers that are 1 inch thick to house 2 AC bearings back to back to replace those BK things.
I did that on my mill using 7201-2rs (1605 ballscrews). I'll never go back to niether standard or thrust types ever again!.

That seems to be the general consensus from comments. I didnt know the ballscrew bearings/units were a weak area but I do now. I could just get better quality bearings and swap out the generic ones. Take your point about custom bearing housings espec to support a pulley/belt system as the z axis driver.

**JAZZCNC** · 18-09-2021

Originally Posted by marbles

. I didnt know the ballscrew bearings/units were a weak area but I do now. I could just get better quality bearings and swap out the generic ones.

There is nothing wrong with the BK-type housing, it's the correct component for the job, it's just that the cheap ones come with crappy bearings. So just replace the bearings with angular contact bearings.

This will be much simpler than making plates and fitting bearings into them because if you don't bore the opposing bearing pockets perfectly concentric to each other then you'll introduce more issues.!

**marbles** · 18-09-2021

Originally Posted by JAZZCNC

There is nothing wrong with the BK-type housing, it's the correct component for the job, it's just that the cheap ones come with crappy bearings. So just replace the bearings with angular contact bearings.

This will be much simpler than making plates and fitting bearings into them because if you don't bore the opposing bearing pockets perfectly concentric to each other then you'll introduce more issues.!

Cheers Dean, will get on it and order up a set. I've got 1605 ballscrews so prob 7201-2rs as dazp1976 says

**dazp1976** · 22-09-2021

Originally Posted by marbles

Cheers Dean, will get on it and order up a set. I've got 1605 ballscrews so prob 7201-2rs as dazp1976 says

The 7201 have a 32mm od. (32xx12x10mm).
I think the BK blocks take a 28mm od bearing. 28x12x9mm if memory serves correct.

I chose to custom mine to fit the 7201 just for a little more strength.