Yeah, that was my guess too. For comparison, one of my desktops has a thing that reports the fan speeds in that machine; it says the case fan there is doing 1.5K RPM, and the CPU fan 5K. Going by that, since these are going considerably faster than that case fan, I'm going to say these are doing roughly 3K-4K or so. Since they are 120VAC fans, i.e. 60Hz AC input, if I had remembered enough EE, I should have been able to work out the speed from the number of poles on the rotor, etc, but alas that's beyond me. Nope, the cylindrical (outer part of the) bearing is a plain cylinder. But looking at it closely, it's probably not copper, so it might be that Oilite stuff. Pretty much about 1/4". I'm just worried a bit about a grease, given the high speed. For comparison, a car wheel is about 2' in diameter, or about 6' in circumference, so at 60 MPH, which is 5280 FPM, it's going to be doing about 880 RPM, somewhat slower. Hence my thinking a fluid lubricant might be the way to go, although of course fluids can migrate. No, it's not, which is exactly the problem, though - I want something that won't coagulate if left to sit for a long period. Actually, now that I think of it, my son is a Mech E - I should ask _him_! :-) They probably know about all this stuff! Noel