Bearing precision levels

[AndySomogyi]

I looked up a Timken 362B and it looks like a typical automotive type tapered roller bearing that costs less than $20.00 each. I don't think they fall into an accuracy class, Andy.

One idea might be to contact Timken and see if they do have accuracy class rated bearings in this size. Since you're already in there, makes sense to just put good bearings in there and I would change the pair if it was me. I have ABEC 3 bearings in my Sherline machines and P5/ABEC 5 angular contact bearings in my mill; my larger lathe has P6 bearings. Run out on all these machines is from 0.0000 to 0.0001" TIR.

Precision bearings make a difference and I would consider them.

I'll see what I can find, and what can afford. Timken has "standard" classes of 4 and 2, and precision classes of 3, 0, 00, and 000. No idea how these classes compare with P/ABEC classes. I do know this bearing is a very common size, and is available from tons of different manufacturers.

It does look like someone replaced the factory standard class-2 bearings with class-0. But unfortunately, the rear bearing shows some damage, both in the race, and from hammer marks on the cone.

I did check runout with the spindle installed, and properly pre-loaded, at the front, it's about 0.0001, and about 0.0003 at the rear. The front looks good, so I think I'll just leave it, as it operates smoothly and quietly, and shows virtually no runout. The higher 0.0003 in the rear might be from damage, I don't know.

I think I might have to call some bearing suppliers, because I'm not having much luck searching for bearings with different classes online.

 

[mikey]

I think I might have to call some bearing suppliers, because I'm not having much luck searching for bearings with different classes online.

I usually contact the manufacturer's tech support department. These guys know their products and can give you accurate information. SKF, FAG and Nachi have been very responsive to my inquiries in the past.

 

[extropic]

Andy,
I'm not a bearing expert so have nothing to add to your identification issues or your search for high precision replacements.
However, I think one of your questions was where to put the best bearing (front or rear). I think I would put the best bearing (new, high precision) near the chuck. If you reuse the bearing that is currently near the chuck (assuming it's not a higher precision class than the new bearing), move it to the rear of the spindle. My rationale is that the loads are usually highest near the chuck (unless you're turning long, heavy work pieces). I would want the best bearing taking the highest loads. YMMV

 

[AndySomogyi]

These are Timken precision class bearings. Even after searching around for a while, they were expensive.

Notice these marks on them, they are bearing alignment marks. Alignment marks are only on the precision class bearings, they are not found on standard bearings.

The alignment marks indicate the area of maximum eccentricity. The alignment marks should all be aligned with each other. The idea is you want to align all of the eccentricities, so that when the shaft rotates, it remains parallel to the Z axis. It the eccentric is not aligned, you might introduce a wobble in the shaft. It is MUCH easier to compensate for a eccentric than it is for a wobble.

 

[Optic Eyes]

I replaced spindle bearings in Kitamora vertical CNC machining center, The engineer ordered Class nine angular contact bearings, I told him class five was better in this application, he insisted, so I put them in, lasted a month, another set went in, replaced in a month, finally class five bearings were installed, ran three years two shifts six days a week.
Class 9 bearings are for moving something slowly and accurately like in Transits, or inspection equipment,
Class 5 bearings are for spindles on Grinders or milling machines with high spindle speeds. and no, Bridgeport's aren't high speed.
Timken bearings are so tough the put them on Steam Locomotives, many large machines use them on spindles.
If the spindle of a mill has bearings that run out a tenth, ask yourself what is the effect on a half inch cutter, even a one inch cutter?
Waste your money if you want to its yours.

 

[Dabbler]

hey @Optic Eyes I don't want to be contentious, but I wonder how you concluded that ABEC 9 bearings are exclusively slow moving bearings? My Browne and Sharpe surface grinder has ABEC 7 bearings in its spindle and has done thousands of hours of grinding at 3600+ RPM. I got it from a grinding shop and it was used on shift work.

Of couse there is a lot more to this than just the bearing class, which is what I think your are alluding to - the type of seal, and hence it's lubrication and or cooling is a key determinant in bearing life.