[Gary Dillard]

Just be careful blindly using a clearance hole chart; the close and loose fits are based on assumed fabrication/position tolerances. The reason a hole is slightly oversized is that you are lining up multiple holes in 2 or more different parts, and the holes which are 2.000 apart on one part may be 2.005 on the other part. Picture taking 2 concentric circles and moving them apart - the open area where you can fit a bolt gets smaller. If you are drilling all of your holes in a pattern on a CNC mill in one setup, you're probably OK; if you're scribing and using a drill press with multiple setups, you'll have quite a bit more tolerance.

However, even with all that, if you are just building 1 or 2 (or even 4 or 5) assemblies, then you can start with the standard clearance hole and match drill / ream anything that doesn't line up enough to get a bolt in if everything else lines up for your needs.