When I was looking for some die making references some time back I found this ball bearing information. I think it might be worth passing on.
In the “Races” Bullet 1 there is some text misplaced - “and the steel” should match with “usually warps.”
This reminds me that one of the most handy things about using the SketchUp 8 drawing program is the ability to go to the 3D Warehouse and grab an already drawn component from that library and use it in my drawing. This is an example.