I also use the HF Drillmaster rotary tool. I bought it for the screw cap that holds the collet. My dremel is old (early 70's to work on N gauge model trains). I also have the speed controller from that era. I needed a different size screw cap because the new flex shaft needed a different thread size than the old dremel. When I got the HF Drillmaster home noticed it used a 12v DC power supply. Plugged it into the old dremel speed controller and voila, got it slow enough to work well, but so slow that too much pressure stopped its motor. It takes the dremel collets and tools. So far I have used it with the polishing pads that look like scotchbrite, felt pads with 240 greaseless and Mother's chrome polish. Haven't encountered kickback or anything similar. It takes a looonng time to get through the gook, but doesn't scratch.