spindle bearing fitment and retention

[PeterT]

Thanks. So dumb question. If we squeeze the bearing set via red arrows on outer race until they contact, they become set to their stated preload. Why do we need the ledge near green arrow at all? For example if if there was a 0.005" gap there, where else could the bearings migrate laterally? Aren't they fully constrained by their 1) their OD & ID faces inline along spindle & housing 2) the AC races & 3) the red arrow axial squeeze on outer races locking them axially?
What suppliers or catalogs are you looking up matched ACB sets for this application?

 

[TorontoBuilder]

Thanks. So dumb question. If we squeeze the bearing set via red arrows on outer race until they contact, they become set to their stated preload. Why do we need the ledge near green arrow at all? For example if if there was a 0.005" gap there, where else could the bearings migrate laterally? Aren't they fully constrained by their 1) their OD & ID faces inline along spindle & housing 2) the AC races & 3) the red arrow axial squeeze on outer races locking them axially?
What suppliers or catalogs are you looking up matched ACB sets for this application?

to equalize the load across the face of the bearing.

I'll use a torque wrench to tighten both ends so that in theory the same force will be on both the inner and outer races.

 

[RobinHood]

Are you using a sleeve to constrain the inner races (blue to green arrow) of the ACBs?

Putting pressure on only the inner race of the first ACB @ green arrow (with your nut on the pulley end) will not properly constrain the set-up.

You could use the nut on the pulley end to push the inner race of the deep groove ball bearing, spacer sleeve, inner races of the ACBs to the shoulder (at green arrow). This arrangement requires the outer race of the deep groove ball bearing to be floating.

 

[TorontoBuilder]

View attachment 56662

Are you using a sleeve to constrain the inner races (blue to green arrow) of the ACBs?

Putting pressure on only the inner race of the first ACB @ green arrow (with your nut on the pulley end) will not properly constrain the set-up.

You could use the nut on the pulley end to push the inner race of the deep groove ball bearing, spacer sleeve, inner races of the ACBs to the shoulder (at green arrow). This arrangement requires the outer race of the deep groove ball bearing to be floating.

damn I completely overlooked that. Thanks

 

[TorontoBuilder]

I'll copy the aciera spindle mcgyver posted... use a nut to retain that side as well. Prefit the bearings and nut then insert into spindle housing....

 

[RobinHood]

That will work; this is how the spindle on my INGAR surface grinder is set-up.

 

[PeterT]

So it seems to me we have come full circle? If we replace the single deep groove bearing of the magneto spindle design with a matched ACB pair set (2 blue bearings), isn't it the same principle?

Tell me if I have my (matched ACB) recipe checklist correct.

- 4 'constraint' features, 2 on outer race & 2 on inner race once pre-adjusted (red arrows). They can be 'fixed' constraints like a lip on the shaft or housing. Or semi-fixed dimensionally like a ring, shim or spacer tube acting on either inner or outer race.

- At least one constraint needs to be adjustable, for example the threaded nut that squeezes the matched set together.

- the constraints must be perfectly in vertical alignment with one another, otherwise there will be a gap somewhere resulting in un-equal face to face loading to the bearing set. For example we don't have to draw in the purple face to face arrows between the bearings as long as the 4 red outer constraints are in alignment. But if they were not in alignment, all bets are off.

- the bearing ID & OD surfaces are sized such that they have sufficient interference on the surfaces at operating temp to stay in position radially, but they can be slid or displaced via the horizontal adjustment mechanism

Now if the ACB's are NOT a factory MATCHED SET set, we have to do or check other things dimensionally to ensure the equivalent to ^above^ because we can no longer count on (my understanding) what matched ACB's conveniently provide us: once squeezed together they deliver the specified preload or axial lay for the intended purpose.

Comment or correct away as needed.

 

[wmetfab]

Im amazed at the level of talent here znd such interesting discussions and pushing the envelope of prescision and inspiration for us home hobbyist types

Im happy (and lucky) if I can do machining and get .010 accuracy
You guys: "Oh, lets just make a new high precision spindle for the milling machine!"
Me: stick welder cutting torch and grinder... "me cave man"

Best of the season to all of you on here.
May the dreams of your next machine come true in 2025

 

[TorontoBuilder]

So it seems to me we have come full circle? If we replace the single deep groove bearing of the magneto spindle design with a matched ACB pair set (2 blue bearings), isn't it the same principle?

Tell me if I have my (matched ACB) recipe checklist correct.

- 4 'constraint' features, 2 on outer race & 2 on inner race once pre-adjusted (red arrows). They can be 'fixed' constraints like a lip on the shaft or housing. Or semi-fixed dimensionally like a ring, shim or spacer tube acting on either inner or outer race.

- At least one constraint needs to be adjustable, for example the threaded nut that squeezes the matched set together.

- the constraints must be perfectly in vertical alignment with one another, otherwise there will be a gap somewhere resulting in un-equal face to face loading to the bearing set. For example we don't have to draw in the purple face to face arrows between the bearings as long as the 4 red outer constraints are in alignment. But if they were not in alignment, all bets are off.

- the bearing ID & OD surfaces are sized such that they have sufficient interference on the surfaces at operating temp to stay in position radially, but they can be slid or displaced via the horizontal adjustment mechanism

Now if the ACB's are NOT a factory MATCHED SET set, we have to do or check other things dimensionally to ensure the equivalent to ^above^ because we can no longer count on (my understanding) what matched ACB's conveniently provide us: once squeezed together they deliver the specified preload or axial lay for the intended purpose.

Comment or correct away as needed.

View attachment 56675View attachment 56678

Huh, I thought you were instructing me?

I'm trusting that when skg says I can buy universally matching bearings that are sold individually rather than matching, and put them together either face to face, back to back or even in tandem they will work for axial clearance and meet the claimed preload

 

[PeterT]

That's why I was wondering how far down the actual catalog/purchase path you got. If you have some references, fire away.

I can see matching meaning 1) they are ground to some predetermined spec so it doesn't matter if you buy 2 or 10, you could put a pair together from any in the batch & they will yield the preload tolerance = maybe what you are referring to 2) you must buy them as a pair only & they are intended to work together to deliver that spec. If they need to be replaced, they both need to be replaced. Now here I am talking single row ACB's & specifically the style that is meant to be squeezed together, faces in contact. I have also seen double row or other variations as a cartridge but I think they are spendy & specialized, outside our scope. I had this semi-figured out some time ago but have apparently lost my notes. I had a really good bearing guide that explained this a bit better but its MIA. I get the impression that different bearing manufacturers (or is it YouTubers) use the word 'match' kind of loose & free.