For my turning applications, I generally hand grind all of my own
tooling. I use high-speed steel with 5% Cobalt. This material has
better heat resistance than regular high-speed steel. I resharpen the
tooling frequently, but not obsessively. I rarely take a cut larger
than 0.0075", but I have a tiny lathe and mill.
For drilling, either 5% cobalt drill bits, or carbide drills work
fairly well. If I have access to a larger machine, I will drill 1/2"
holes in the bar stock, otherwise I usually stop at 3/8". From there
I use a hand ground boring bar to bring the inside diameter up to the
appropriate ring size.
Hope this is interesting or useful to somebody,
Daniel J. Statman, Statman Designs