Hello everyone. I've been having some issues with the spindle on my PM30 and I need some advice on how to proceed.

When I first got the mill, it worked OK, but I had always planned on going to a belt drive, so I didn't test it a whole lot.. The mill was making some noise in the spindle and was getting warm after only 15-20 minutes of use. I decided it was time to mess with the spindle. I replaced the lower 2 bearings with angular contact bearings and the noise went away, and it runs a LOT better. Before, I wasn't able to run at full speed for very long, it would just get too hot. Now, I can run at ~1500-2k RPM without excessive heat or noise.

HOWEVER, when I go above ~1500 RPM (my high speed pulley maxes our around 5k), I get a LOT of heat, and quickly. After only 15 minutes, the top bearing (the one visible from the top of the head) gets up to around 140 F. I've stripped everything down on the head and ran some tests and all the heat is generating from that one spot. After 15 minutes, the top bearing will be at 140F, the bottom bearing is only around 100-110, the quill housing is just a few degrees above ambient, etc.

When it heats up, the whole assembly is VERY tight and although it spins smoothly (no grinding or tight spots), there is a lot of resistance. This is without the belt attached, and the whole quill mechanism OUT of the mill. The top two bearings with the gear part between them, that whole thing has a lot of resistance to it. When it heats up, it gets significantly worse, and it gets very hard to turn. Of course, when this starts happening, my motor starts getting really warm because of the added load.

So, that's the back story.

I tried to remove the bearing assembly with a mallet. Then I tried using a jig I made using a long 3/4" bolt and a 0.5" plate of aluminum to pull it out. The aluminum bent under the force and the bearings didn't budge (yes, I removed the snap rings :-) ). I ended up using a 12 ton shop press and it finally came out with a huge BANG after nearly 3 full pumps on the handle. It was in there good.

With everything removed, the bearings actually move pretty freely and as expected. I bought new bearings, but they feel about the same honestly. I'm wondering if the hole for the bearing(s) are too small in diamter and it was just pressed in there too hard? I measured the top, and it was about 0.06mm too small, or ~0.0025". Also, would misalignment of the top and bottom holes cause this?

At this point, I'm wondering what to do. I don't want to just swap the bearings with the new ones and press it all back together, that doesn't seem like it would solve the problems.

Here's a video to try and give an idea of the resistance of the spindle: