The one on the left currently runs at 3200rpm. The one on the right I have installed an in line rheostat that allows me to go from 1750rpm down to 400rpm. I hope to build a heartier one for the 8" grinder to get the Rpms down to 800. I will have to make sure I can handle a full 15amps.

CHRIS, Charlottetown PEI Canada. Anytime you can repurpose, reuse, or recycle, everyone wins!