[Cory]

Originally Posted by vivek16

A good rule of thumb for reasonably sized bearings (say .75-2") is a .005" interference. You can get more specific as others have said but it will work.

-Vivek

I wouldn't generalize that much. 0.0005" is good enough for a 3/4" bearing. I had to make a part for a large bearing (about 1.5-1.75" or so) and the reccomended max interference was 0.0002"-0.0003". The extra 2 tenths can make a HUGE difference in how freely the bearing can turn.