Wondering if anyone here has done any machining and hardening of HSS like M2 or M4. I've never worked with the stuff. It's expensive, so I'd rather not invest the money, if it's going to be impossible with my equipment. I have an idea for a circle cutter (similar to a trepanning tool) that would proably be more successful with a HSS blade. I'd need to cut some .140" wide slots, 1" long in 1/8" thick flat stock. I don't have a furnace, but have been very successful hardening and tempering tool steels like O-1, A2, W-1 with a torch. McMaster sells unhardened M4 flat s with a hardness of B95, and yield strength of 60,000 PSI. I have carbide end mills and an old tired Bridgeport to work with. No grinding equipment here except for a bench grinder. Would the M2 destroy the end mills in short order? Think I could control the heat treat? I suppose I could also try something like D2, which is known for wear resistance, but I have never cut and heat treated that either.