Angular Contact Bearing mount

[elf]

The mounting bracket for my ballscrew angular contact bearings has the bearings separated by 15mm with only the outer race supported:

I think this defeats the purpose of the angular contact bearings and regular deep groove bearings would work as well if a spacer was added to support the inner races. What say you?

[mikey553]

This is a good design. You adjust the bearing preload with the nut on the ball screw by moving inner races. Do you have this on your ball screw?
Regular deep groove ball bearings can carry axial load too, but not as much as angular contact bearings.

[Galaxie]

What he said.^^^

If you do use a spacer between the bearing inner races, the spacer must be sized to allow proper pre-load.

[elf]

Unfortunately, there was no torque setting supplied, so it will be a guessing game 😀

[Rich Carlstedt]

Yes, you have a "adjustable preload' configuration.
Why not make a bushing that matches the EXACT length of the bore shoulder and place it
on the leadscrew. Precision bearing are made so when the outer and inner race are EXACTLY in the same plane, you have the correct preload.
Rich

[Randy]

+1 on what Rich C wrote. I just happened to watch Robin Renzetti's video on precision spindles. He covers this in the first few minutes.
https://www.youtube.com/watch?v=grUd...hannel=ROBRENZ

[elf]

Exact is a somewhat inexact term in machining I suspect the tolerances need to be less than a handful of microns. The video was well worth watching all the way through. Thanks.

[JRouche]

The mounting bracket for my ballscrew angular contact bearings has the bearings separated by 15mm with only the outer race supported:


I think this defeats the purpose of the angular contact bearings and regular deep groove bearings would work as well if a spacer was added to support the inner races. What say you?

What say me? I think you are on a good track. JR

Fuk, I hate redoing my post. So hear goes. JR


I like the both bearings. I have some on hand.. I am not sure but I dont see a diff with deep whatever and normal angular sets. Regular cut saw works just fine. JR

[Mcgyver]

we've only got half the picture. You can't assess the design of an AC bearing mount without knowing how they are fixed on the shaft. Also note, precision AC's, where they are a press, are a very light press and as far as I can recall, every instance that I've seen them used or that I have designed something using them, both the inner and outraces get mechanically fixed in place

I do not like the design. Consider: IF there is a spacer and the inner race are locked together (via nuts on the shaft) and (of course) the out races are similarly locked into the housing it could would work. However the length of the shoulder in your diagram vs the inner spacer length is critical to it working properly. Having the outer race spacer integral to the housing as shoulders makes it difficult to machine and measure to the accuracy required for precision AC's (we're talking tenths).

A better design instead of a shoulder in the housing would be a spacer, then you can grind it with the shaft spacer if you have match bearings, or make whatever adjustments you need to get the desired preload if using universal bearings.

[mikey553]

we've only got half the picture. You can't assess the design of an AC bearing mount without knowing how they are fixed on the shaft. Also note, precision AC's, where they are a press, are a very light press and as far as I can recall, every instance that I've seen them used or that I have designed something using them, both the inner and outraces get mechanically fixed in place

I do not like the design. Consider: IF there is a spacer and the inner race are locked together (via nuts on the shaft) and (of course) the out races are similarly locked into the housing it could would work. However the length of the shoulder in your diagram vs the inner spacer length is critical to it working properly. Having the outer race spacer integral to the housing as shoulders makes it difficult to machine and measure to the accuracy required for precision AC's (we're talking tenths).

A better design instead of a shoulder in the housing would be a spacer, then you can grind it with the shaft spacer if you have match bearings, or make whatever adjustments you need to get the desired preload if using universal bearings.

I can agree with your points, but this design is very common since it is cheap to produce and compact in size. It is difficult to make precise, but again this just a ball screw, not a precision high speed spindle.

[Mcgyver]

I can agree with your points, but this design is very common since it is cheap to produce and compact in size. It is difficult to make precise, but again this just a ball screw, not a precision high speed spindle.

ok, but 1) how do we know how it locks into position on the shaft and 2) if you can get the two spacers dead on, it will either will seize up (to much preload) or have backlash (which you don't want for cnc climb milling).

If it can't be be done right, and its not that demanding an application, I'd be more inclined to go with a double AC...then you simple have to fix it on the shaft and in the housing

[JoeLee]

How do the balls recirculate ?? Or don't they.
JL.....

[Toolguy]

I would have a shoulder on the shaft for a solid stop on one inner race, a spacer between them, the same length as the ledge for the outer races, then a nut on the end to clamp it all together. Then you don't have to worry about the nut being too tight. If you make the spacer a couple thou. too long, you can work it down a little at a time until it's just right. The inner races can be a close slip fit on the shaft so it won't be hard to get them on or off.

[elf]

How do the balls recirculate ?? Or don't they.
JL.....

It's the angular contact bearings, not the ballscrew nuts.

[elf]

we've only got half the picture. You can't assess the design of an AC bearing mount without knowing how they are fixed on the shaft.

The ballscrew threads are turned off, so the inner race of one bearing rests against those. The outer end uses a common lock nut to secure the assembly. Definitely not a precision spindle😁