Not quite sure whether this is the place to post this, but here goes.

I'm doing a project at uni where I need to do some isolation routing of pcbs, but wanted to make a spindle as cheaply as possible. I have decided to go about it by having the milling bit sit between a bunch of 624 bearings, that are tensioned onto it. Here is my test rig:

Attachment 210072

You can't see the bit, but it's attached to the prop saver (blue thing) at the top. The 4mm shafts at the bottom will be cut flush. I'll power the thing with a brushless motor, I hope to spin it at about 40000rpm. (it works well at 20k at the moment, but I need a faster motor). The motor will have another prop saver, and the rotation will be coupled with a thick o-ring.

Has anyone successfully used this method of making a spindle/have any comments?