Jim Stewart wrote:

I have a piece of CRS, about a foot square
and 1" thick. I want to cut out 2 disks about
4" in diameter. I will ultimately turn and
finish them into flywheels.

Given my tools, here are my options:

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

2. Mount plate on rotary table, taking small
passes mill out disk, finish on lathe.

3. Try to cut out disk with sabre saw,
finish on lathe. Painful just thinking
about it...

Any other options or suggestions?

Forget the saber saw. If it were me I'd certainly flame cut the plate.

This would be a good application for one of those Val-cut trepanning tools, just
bolt the plate to your mill table and trepan your 4" disks. If you really knew
what you were doing you could maybe grind a trepanning bit you could use in a
boring head.

GWE