rmac311,
Could you define your problem a little better? For each fit class, the Machinery's Handbook provides tolerance tables with recommended tolerances for holes and shafts. It also provides the clearances and interferences, so that you can calculate your own tolerances when you do not control both pieces.
If you want to control the forces and stresses from the interference, you are in the wrong forum. Perhaps you should look in one of the mechanical engineering forums.
JHG