I don't use my router much. I haven't had it out of the table since I first put it in, and I've had the same roundover bit in the thing for I don't know how many years.
Well, I was knocking out some little raised panel looking thingies to nail to the bottom of an interior door that stays propped open, and which was badly chipped across the bottom. I got a wild hare and decide to live dangerously and go for an ogee bit. Whooo-hee...
I smoked the hell out of the bearing pilot routing two door panel thingies. Gunked it up with all sorts of crud, and quite possibly ruined it. The same bearing sat on top of the roundover bit for ages, and I've used it to round over lots and lots of things in that time without this happening.
Needless to say, I scorched up the panel thingies but good. Not a big deal since I painted them blue anyway.
Looking at this thing, I think there must have been a spacer that I dropped and lost. The bit set is Crapsman, carbide tipped, and I have one shaft with several interchangeable parts that stack up, and which are secured by a nylock nut at the top. I haven't had that bit disassembled in so long I just can't for the life of me remember whether there was a spacer or not, but it looks to me like if the nut on this thing is screwed down tight enough to keep cutter in control, it will prevent the bearing from turning.
So that's the question... Was there a spacer? What did it look like?
(BTW, if you ever decide to put little fancy panel thingies on the bottom of a door to cover up chipping veneer, wait until Lowe's opens and get some of those then brass sheet thingies instead, or otherwise come up with some other plan. A door frame with big relief cuts chiseled out of it to make way for such a thing really looks stupid in retrospect.)