Brian and I have a project cooking to make a lathe chuck backplate, to fit a new 4-jaw chuck onto the big lathe. The style we need, L0 (L-zero, picture here) has a keyway cut into it. We don’t have any way to do that.
Does anybody have a suitable broach? @carl.lance: I hear you have a shaper. Can it cut a 3/8" keyway?