R Henrickson
My brother did a couple for me, since he has access to a metal lathe. He tried taking the teeth off a hole saw. At best, the process frustrated him, and the result was useless. He also turned a taper onto the end of a piece of 2" inside diameter black iron gas pipe. That was reasonably successful, though 1 1/2" I.D. would probably be more useful (I was working on a sphere just over 3" in diameter).