[hub]

hub, without the top bearing assembly, it runs like a dream :-) There is no pre-load in the top bearings, they're just basic ball bearings. The noise and heat is coming from there, so I'm not sure adjusting the preload on those would help anything?

Ok so pre-load is ok then
1) What is the ball bearings RPM rating? (Maybe it can't do high RPM)
2) Maybe misalignment
3) ?

[cowanrg]

Ok so pre-load is ok then
1) What is the ball bearings RPM rating? (Maybe it can't do high RPM)
2) Maybe misalignment
3) ?

good questions!

1) the top one has the lowest rating, and it's rated to 6400. So, 5k is near the upper limit, but still within tolerance. The bottom one is like 8k or something.
2) that's KINDA what I'm thinking, but when I bored out the holes for the bearings I locked the table and the knee and bored them with the quill, after tramming the head top of the PM30 head, so they SHOULD be lined up now.
3) yep.

[hub]

good questions!

1) the top one has the lowest rating, and it's rated to 6400. So, 5k is near the upper limit, but still within tolerance. The bottom one is like 8k or something.
2) that's KINDA what I'm thinking, but when I bored out the holes for the bearings I locked the table and the knee and bored them with the quill, after tramming the head top of the PM30 head, so they SHOULD be lined up now.
3) yep.

I'm betting on misalignment (best guess). It only takes a very tiny bit and it starts to heat up, but in that case I would expect there would be some resistance when turning by hand.