The BEST Bits I've known were by a Company called "Butterfield".
Long run of Copper / Nickel ("Carra-Dur") valve guides.
The "Basic" bit that we chose cost about $15.00 a pop, in quantities of 50. Some would make 25-30 holes,....some would give up on the first part.
One thing I learned from Butterfield's "Tech Rep", a verifier at 30 + years of chewing on metal,
.....HIT the damn work piece turning and MAKE a hole .
If you have to "Sneak up on a cut" something's wrong.
Larger holes,....I'm a BIG fan of the Rota-broach / Ream method, been using it on Soil Engagement pieces,..... Cutting edges and such (HARD chit)
The new "Indexables" are worth along look, too.
Fast, and cost efficient v. "Bits"
GTC
