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Centec 2A Rebuild
Pete.:
Can't see much of the inside face of that taper cup but it doesn't look anything like bad enough to give the lash figures you're quoting from wear alone (in fact I can't imagine any complete bearing giving 10 thou play).
How tight was the spindle to pull out of the inner bearings? If it was very tight it might simply mean that friction was making it impossible to adjust.
By the way image resizer I use:
http://www.bricelam.net/ImageResizer/
You can resize the whole bunch in one hit, either creating new files or re-sizing the originals.
PekkaNF:
At work we use mostly pretty big carb bearings, some taper roller bearings, and seldom angular contact bearings....some stuff I have picked up. If you can measure fault, bearing is really rough. Three most common problems are: Assembly problems, lubrication faults, counterfeit bearings. New brand name standard bearings have better running accuracy than older bearings. Some new deep groove ball bearings are pretty damn close P5. Problem is the bearing clearance and mounting accuracy. It is hard to keep tolerances on check. When we are talking spindle bearings, bearing/part/fit tolerances are conspiring against you. You can find bunch of perfect bearings and some of them will slide on shaft and some needs press. This sort of changes internal clearance. Also it would effect on preload, or how you can adjust it. Sometimes you have one shot at 80 decgrees C while it is still moving and then run intermitent until it setteles and stabilizes.
This thread has lot of ramblings and some things I learned. Not sure if it applicable to you, you have diferent bearings.
http://madmodder.net/index.php/topic,12269.msg146280.html#msg146280
It's still working, not sure if it success, let's see few tens more hours of running. Now it is quiet, but still can't measure real problems with original bearings.
Pekka
timby:
--- Quote from: mm289 on December 27, 2017, 07:41:09 AM ---
The bad news was that although my spindle run out with "no load" was only about 1 thou, when any side load was applied it was up to 7 thou and the end float when applying load (pushing/pulling the pulley) was 10 thou.
This was with the bearing pre load way higher than I would like so I think the bearings are knackered.
--- End quote ---
If the bearing surfaces are reasonable I suspect that you need more pre-load .
Try it and do it with the bearings dry it makes a difference.
Your 1 thou. run-out is just over the Timken tolerance for standard bearings, see the PDF link below page 19.
https://www.timken.com/wp-content/uploads/2016/10/Timken-Tapered-Roller-Bearing-Catalog.pdf
You could probably reduce the 1 thou run-out by changing the relative position of the bearings on the shaft.
When I used to use high precision Timken bearings long ago they had a dot on them that indicated the maximum run-out and we assembled them with the dots opposing.
Pete.:
The worst radial runout I see for precision inch taper bearings is .0003" page 25.
mm289:
Interesting input thanks guys. I will reassemble and run a set of tests with both bearings dry, then loosely packed with grease and take some new measurements. couple of thoughts/questions:
1. On the preload the reason I felt it was pretty high was because of the drag it was putting on the spindle rotation, it wasn't running freely and felt like it had a fair bit of resistance. Now I am more used to bearings in automotive applications where overtightening is a recipe for disaster so maybe I am being too cautious?
2. The run out with no load I can live with at 1 thou. What concerned me is the deflection under load. To test this I was just gently pushing/pulling against the side of the chuck with a dial indicator on it and this is where I was getting the 7 thou. Is this a reasonable test?
3. Likewise the end play is the way I test end play on cranks in engines, set up a Dial Indicator then push/pull the shaft and read max deflection - in this case 10 thou. Again is this a reasonable test?
The cups look "ok" but not spectacular but the inner races feel very sloppy to me. The other thing I noticed which I have tried to show in the assembled pics below is that the inner race is not concentric with the outer. If you look at pic 1 you can see that the gap between the inner sleeve and and the cage is less at 6 o'clock than 12 o'clock. In pic 2 I have rotated the cage and now the gap is less at 12 o'clock than 6. I may be missing something but doesn't that mean the bearings will run eccentric or do they only centre under load?
SLow progress so I have started swopping out the single phase motor for a 3 phase and VFD :D
More on that later.
Cheers,
Paul.
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