I use my Dremel a lot! I've gone through several of them in 40 years of building R/C planes and model cars. The brown cutting disks are my "torch" for cutting model car frames, etc. Got to be careful - they will shatter if they bind up! I've had two speed controls for the Dremels. Both have failed. They have become on/off switches - no speed controlling. Kind of a disappointment, since the tools themselves are bulletproof.
Sam