Side-to-side play with new spindle bearings?

[eKretz]

You should not have play. Assuming you are not pushing from the back (or pulling from the front) and overcoming the spring. Axial play in the bearings on that spindle should have been taken up by the spring, if you can move it easily you dont have enough preload (or any). Picture attached should be the same or very similar to your spindle, springs preloading 2 tandem pairs, if you have play you have problems. In this case it could also be play from how the spacers pin to the housings even though your bearings are actually preloaded.

He *is* pushing hard enough to overcome the spring force, as I understand it. But that's a grinder spindle. No milling machine spindles that I'm aware of use this type of setup.

 

[mottrhed]

He *is* pushing hard enough to overcome the spring force, as I understand it.

My point is he would have to push from the rear to have any effect on the springs. Pushing from the front just loads the front bearings more, and if you can move them measurably (a micron or more) with your hand, you werent preloaded much or at all.

 

[mottrhed]

Wow! Thanks for all of the additional feedback guys. I had thought this thread was fading into the background.
Re: type of bearings: A pair of angular contact bearings at the bottom and a single in up at the top. THe original bearings were from New Departure, replacements are a matched pair of 7007s from SKF and a single 7006 at the top.

Re: clearance in the housing. The two bearings bearings for the lower end of the spindle just above the taper were marked -5 in the box from SKF. I measured them around -4um as a sanity check but in a fight i would side with SKF on the true numbers. The bore in the quill measured about +5um, so we are somewhere in the ballpark of 10um clearance between the two. This was my virgin outing replacing spindle bearings and i bought them prior to disassembly hoping for a fast turnaround. If I were to do it again I would try to get a bearing set that more closely matched the bore.

I know some grumpy coot will say " You cant measure to 1um! You cant do that with your Harbor Freight calipers!" So the pre-emptive answer to how I measured the ID of the quill bore and OD of the bearings: Sideways on the surface plate in a V block. 0.00005" BesTest indicator swept for top dead center or bottom dead center. Starret Digi-Check gage block stack adjusted to zero the indicator on upper or lower gage block surface and then read the height directly from the DigiCheck. Subtract.

I did end up putting in some Vibra-Tite but it was a bit of a fiasco. The first time I tried it the Vibra-tite locked up while I was sliding the spindle w/bearings into the quill. The bottle says 20 minute working time so i was moving pretty slow, but i think i only paused for a few seconds for some reason and that was it - stuck.
Huge PIA to disassemble, clean and try again. Second time around I was deliberately light on applying the Vibra-Tite but the assembly went smoothly.
Side-to-side play is now +-0.0002" or so when I push and pull, so better than where I started but I would have hoped for a bit less than that. I think that the Vibra-tite application was light enough that I did not fill the gap as thoroughly as it could have been but i was gun-shy about it locking up again. Or maybe I am overestimating the bearing stiffness, I don't have too many data points to compare against.

cheers,
mike

Sounds like you are fine, those dimensions are ok for this application. That being said, I wouldnt expect to see that radial play if loaded correctly, but in this case its likely good enough for this machine. You shouldnt need the cheaters goop with those sizes.

 

[michiganbuck]

I would test a spindle only after a 5-minute + warm-up, and test that the whole spindle head was not moving, I have seen machines getting a spindle rebuild, and even a new spindle with no improvement.
But do agree with proper preloading the should be no free wiggle

 

[eKretz]

My point is he would have to push from the rear to have any effect on the springs. Pushing from the front just loads the front bearings more, and if you can move them measurably (a micron or more) with your hand, you werent preloaded much or at all.

Is there a spec'd preload in pounds on those? I would generally agree that they should be tight enough not to move very significantly by moderate hand pressure, but I'd think that a good pull (probably more accurate than push, under the circumstances) with body weight behind it might well flex the springs.

 

[mottrhed]

Is there a spec'd preload in pounds on those? I would generally agree that they should be tight enough not to move very significantly by moderate hand pressure, but I'd think that a good pull (probably more accurate than push, under the circumstances) with body weight behind it might well flex the springs.

There is a target preload force depending on a bunch of factors. In this case its probably 100-150lbs.

I think the confusing factor here is that the front housing spacer (the one on the left in my picture-with the holes) gets bolted to the housing, making it essentially part of the casting. The front bearings shoulder against it, then the spring pack is on the other side pushing off of it (and pulling the shaft towards the rear), allowing the rear bearings to expand (slide back) with thermal growth while still holding preload. The front bearings are shouldered against the rigid housing shoulder and cant move towards the rear once they are preloaded without overloading them. So there should be essentially zero axial play when pushing towards the back as the static load rating of a single bearing like that is something like 4200lbs, which doubles since there is a pair in tandem. Now on the other hand, pulling is simply overcoming the spring force and if measured would tell you exactly what the mounted static preload is, but doesnt teach you much else.

 

[Tyrone Shoelaces]

We seem to have gone from discussing a “ Cincinnati Toolmaster “ milling machine to discussing a “ Jones & Shipman “ 540 Surface grinder. Two entirely different machines. Two entirely different spindle set ups.

Regards Tyrone.

 

[ballen]

You should not have play. Assuming you are not pushing from the back (or pulling from the front) and overcoming the spring.

My bad: I should have said "pulling from the front". Just overcoming the preload/expansion spring.

(Further more, as Tyrone has pointed out, my comments about a J&S 540 were and are totally irrelevant. We are discussing a mill spindle here, not a grinder spindle.)

 

[westcoastr]

Wow! Thanks for all of the additional feedback guys. I had thought this thread was fading into the background.
Re: type of bearings: A pair of angular contact bearings at the bottom and a single in up at the top. THe original bearings were from New Departure, replacements are a matched pair of 7007s from SKF and a single 7006 at the top.

Re: clearance in the housing. The two bearings bearings for the lower end of the spindle just above the taper were marked -5 in the box from SKF. I measured them around -4um as a sanity check but in a fight i would side with SKF on the true numbers. The bore in the quill measured about +5um, so we are somewhere in the ballpark of 10um clearance between the two. This was my virgin outing replacing spindle bearings and i bought them prior to disassembly hoping for a fast turnaround. If I were to do it again I would try to get a bearing set that more closely matched the bore.

I know some grumpy coot will say " You cant measure to 1um! You cant do that with your Harbor Freight calipers!" So the pre-emptive answer to how I measured the ID of the quill bore and OD of the bearings: Sideways on the surface plate in a V block. 0.00005" BesTest indicator swept for top dead center or bottom dead center. Starret Digi-Check gage block stack adjusted to zero the indicator on upper or lower gage block surface and then read the height directly from the DigiCheck. Subtract.

I did end up putting in some Vibra-Tite but it was a bit of a fiasco. The first time I tried it the Vibra-tite locked up while I was sliding the spindle w/bearings into the quill. The bottle says 20 minute working time so i was moving pretty slow, but i think i only paused for a few seconds for some reason and that was it - stuck.
Huge PIA to disassemble, clean and try again. Second time around I was deliberately light on applying the Vibra-Tite but the assembly went smoothly.
Side-to-side play is now +-0.0002" or so when I push and pull, so better than where I started but I would have hoped for a bit less than that. I think that the Vibra-tite application was light enough that I did not fill the gap as thoroughly as it could have been but i was gun-shy about it locking up again. Or maybe I am overestimating the bearing stiffness, I don't have too many data points to compare against.

cheers,
mike

Mike, do you remember exactly (full numbers) what bearing were in your spindle? And what exactly you used for the replacements? There are lots of skf 7006/7's out there!

Thx!

 

[michiganbuck]

I would run a spindle for a time before checking. perhaps 15 minuets+.
Dead cold can be a difference from warmed up.
I would add some preload before tearing it down.
After a fresh rebuild there should be no error.