after a lousy 3-4 hours of use. The Harbor Freight speed control box, intended for a router, won't work with the Dremel Moto-tool grinder. Not having the ability to slow down the rpms of the Dremel, for fine work, (like altering the half cock and sear on 1911's to Gold Cup configuration, finishing out the corners of sight dovetails, etc, sucks. Dremel quit making their Speed Control Box, so another source of such a rheostat must be found.