Ball bearing light press fit, lube or no lube?

I am replacing both ball bearings on the arbor of my tablesaw. One is fairly loose a slide fit to allow thermal expansion. I think that should be a dry so it does not accumulate sawdust and get stuck. How about the fixed bearing. It is a tighter fit into the bore. After partial assembly it is forced into the bore by a threaded collar.
So in general should bores be lubed with light oil which would seem to make assembly easier or does it dry out and glue things together so tight they will be hard to take apart in ten years or more?
Of course as I get older I begin to worry less about the need for maintenance in a few decades.
Bill D

I've done a mazillion bearings and have never, ever, considered lubing either bearing fit..that's just not how they work! If the are loose at all they're going to wiggle and fret and ruin one of the fits.

Stuart

They are a press fit for a reason, to be tight. It's like putting lube on a taper lock bushing, Don't.

After I got everything cleaned up I decided you guys are correct they do not need lube. The fits are not as tight as I thought. 60+ years of rust made them harder to take apart then they will need to go together. They are a much lighter press fit then I am used to, No need for a hydraulic press at all for assembly. I had worried about the fine thread locking collar not having enough force to overcome friction.
The rotating shaft is held in the inner bores by threaded nuts so it can not slip. The outer race is captured by a threaded locking ring on the one end. The smaller other bearing race is free to float in the bore so nothing is even a tight press fit.
Light taps with a small hammer will be more then enough to seat everything before tightening it all down.
Bil lD.

Your question is wrong. It is not about lube. It is all about the bearing manufacturer's recommended fit. Please note that a press fit will reduce the internal bearing's running clearance. Squeezed material must go somewhere. This is why your fit must match the manufacturer's requirement. If the bearing is tight, lube is good, especially in a soft material like aluminum to prevent galling.

Bill D said:

I am replacing both ball bearings on the arbor of my tablesaw. One is fairly loose a slide fit to allow thermal expansion. I think that should be a dry so it does not accumulate sawdust and get stuck. How about the fixed bearing. It is a tighter fit into the bore. After partial assembly it is forced into the bore by a threaded collar.
So in general should bores be lubed with light oil which would seem to make assembly easier or does it dry out and glue things together so tight they will be hard to take apart in ten years or more?
Of course as I get older I begin to worry less about the need for maintenance in a few decades.
Bill D

Click to expand...

I would always use a lube. Liquid friction is less than solid friction. Why take a chance on galling in the bore. If the press fit tolerances are right the oil will not make a difference to the fit.

Roger

In the industrial world I have seen both but usually without lube. Those those that do use lube use a very thin coat and it does not appear to harm anything.

What these posts show is there is no 'must do' way...it seems that a variety of ways work OK. I've pondered this topic for years. As for lube, it's fair to assume the lube will be 'squished' out by the tight fit anyway....whatever is left won't be significant.

And even more, 'is a press fit really needed?' Some bearings are really pressed on tight, other are hand-removable. For example, millions of Chrysler transmissions were built with the output shaft bearing (a fairly big ball bearing) that is a slip fit (hand) on the shaft. No press at all. Yet they never fail.