The online buffing and polishing guide states some ballpark figures for wheel speeds in surface feet per minute, but I'm looking for more specific info, particularly when it comes to aluminum and steel. (Not stainless)

What's a good target speed for aluminum? How about steel? Is it better to be a bit under, or a bit over the "ideal" speed? I ran up a quick chart in Excel to calc surface speeds for a given RPM and wheel size and it seems like it wouldn't be that difficult to hit the "sweet spot" by varying wheel size. Anything I can do to ease my effort and make the tool do the work, right??