Last year for Christmas I was given an 8" bench grinder. At the time I did realize that what I wanted was a slower speed(1750). Is it possible to put in an inline circuit to slow down a 3500RPM grinder? I though about putting a rheostat inline with the power cord but do not know if this will do any harm. Can someone give me some insight here? Thanks, Bryant
Cutting the current won't do it unless it's a DC or universal motor. Not likely it is. Your alternatives are to to generate a different frequency at the same voltage or live with it.
Lots of mythology about scuffing steel with a stone. Twice as fast in RPM means twice the removal is possible in the same amount of time, all other factors being equal. Period, end of sentence. What anyone else, regardless their manufacturing affiliation may say, is simply silly. If your stone is a full 8, you're already moving more grit in the same amount of time than a 6" stone at the same RPM.
That said, a low speed is more forgiving of momentary angular deviations and imbalance. These I count as plusses, and since I'm not interested in removing much steel (grinding) to change shape, but taking a bit off the shape I have to sharpen, I like slow and 6.
Friction and the heat produced does not depend on stone speed, but pressure, and
time, when you consider that the metal has to conduct the heat away. Once again, no big deal, because you're not normally recontouring, which wants coarse rather than long.