[FigureLLC]

if i recall properly, the recommended surface speeds for polishing aluminum are something like 3600-7500 surface feet per minute. figure it out like this:

C (surface length of wheel in feet (circumference)) = 3.14*D/12, where D is diameter of wheel.
RPM of motor should be marked on tool.
SFPM (surface feet per minute) = C*RPM

so for a 3600RPM motor, with an 8" wheel, you'd have
3.14*8/12*3600=7536 SFPM

i think this is right, but it's real early and cold.

also, i think varying the voltage to an a/c motor is a bad way adjust speed. i've done it before, but i'm learning more about a/c motors at the present, and i've read some things that said they don't work that way. i'm not sure what happens over time. like i said, i've done it (and to one motor i use on a daily basis).