"Jim Stewart" wrote in message
...

1. Rough out the disk with the gas axe,
grind away kerf with angle grinder,
turn on lathe.

Any other options or suggestions?

Gas axe, but center pop the middle of the disk, and attach a trammel point
to the torch, approx 2 1/8" from the edge of the center hole, at the right
height to keep the flame the correct distance off the steel. You _will_ be
amazed at how smooth you can cut, once you figure this out. Of course, right
sized, CLEAN tip, with correct cutting pressures for the steel indicated are
assumed. I can email a picture, if you don't know what I'm talking about.