[ipburbank]

Hello,
I have a rookie question: to accomplish a bearing setup like this one (from a build thread) how do you keep the inner band of the bearing from rubbing?

Istvan.

[Web Goblin]

A little bit picky but the shaft on the ballscrew would need to be turned down to a plain section from before where it enters the bearing to the correct length for where it goes into the stepper coupling.
As for rubbing do you mean the screw part of the shaft rubbing the inner bearing ring or the inner bearing ring rubbing against the mount?
The shaft would normally have the screw part turned down to a plain section then it would have a spacer ring between end of the screwed section and the bearing allowing it to rotate freely. If the inner ring is rubbing against the mount then make the inner hole in the mount bigger to allow clearance of the inner ring and shaft, the outer ring of the bearing will support the load. Whats the coupling on the right hand side of the bearing mount for?

[RICHARD ZASTROW]

Why not just use a pair of inexpensive angular contact bearings like the rest of the world? That would radial and axial support in a less complicated set-up than the one in the link.

Dick Z

[ipburbank]

Hello, thanks for the reply.

Why not just use a pair of inexpensive angular contact bearings like the rest of the world?

Dick Z

I am not familiar with bearing shopping, but on mcmaster the cheapest sealed bearing for my screw (.5") is this one:
6680K34
That is $126.10 -- is there something else I should be looking for?

Regards,
Istvan.

[rbraeking]

The drawing shows 2 thrust bearings that are held by the set collar and coupling. I would imagine that there would be enough contact area if this were clamped to a fine enough lead screw but I don't believe it would work on a ball screw. The key to any design is to minimize the shifting of the screw within the mechanism which translates to backlash. That design consideration is balanced against the increase in friction associated with high preload in the bearing system. You could use angular contact ball bearings (they worked on 57 chevy front wheels) or tapered roller bearings. If you want to have the thrust taken up on only one end of your screw then a 2 row ball bearing would do the trick.