so you are grinding on steel now? i though you were just drilling holes. are we talking about heavy work or just small stuff like engine mounts? it shouldn't hurt the grinding stone to get hot. the drill getting hot (I assume you mean drill bits not the drill motor), the drill bits will heat up a bit, but slow speed, heavy feed is the way to go. they will get somewhat hot, but if it is smoking hot or really burns your fingers, it is too hot. something to lube it helps too. as long as you are getting nice spiral chips instead of just dust and powder you are ok. once it stops cutting and if you hear it squealing, that drill bit is most likely toast! you can re-sharpen them, but that takes a bit of practice or a bit sharpener. now on the other hand if your drill motor is heating up, then it sounds like you are trying to cut some pretty heavy stuff. a little bit is ok, but it if it getting really hot, it will not live long.