Awl --
My buddy, an old-school machinist with a cupla old Hurco's, is making SS parts baskets for his heat treater -- constantly dipped in molten KCN.
He's spotting/drilling *thousands* of 5/16 holes in 1/8" 304 SS, first spotting with a 3/8 drill to get a bit of a c-sink.
Here's the skinny:
- With soluble oil, carbide outperformed cobalt, but not by a lot. Not clear what grade the carbide was, or the cobalt -- just took whatever Traverse gave him.
- With Crisco, the cobalt is outperforming the carbide *by a lot*. A lot-lot! And that includes a carbide drill I gave him, which I believe was good quality.
He says the side flutes of the carbide were actually wearing away.
Weird, eh? Suggests some kind of chemical/metallurgical interaction amongst the drill, Crisco, SS.