I just bought the inserts Tormach sells with the Superfly. As I said above, the inserts sold for aluminum work great. I haven't done much with mild steel (used flood coolant). Results were just OK, but I wasn't trying for anything special so my speeds and feeds were just guesses. I.m sure I could have improved the finish with better machine settings. Haven't done any other materials. Sorry, I'm in a rush so didn't look up the part numbers or specs on the Tormach inserts.