Strange as it sounds, but cobalt or HSS seems to work very well, as long as they are the black oxide coated ones. I have had no luck with the standard M42 or the bright finish HSS.
Wow, this thread got pretty buisy. I think psychomill has very well stated most of the points I was trying to make.
To answer one of your previous question (and I know I will get hate-mail for it) Yes, there are lots of shops that either do not understand TP tolerances (let alone the difference...
I am not sure if I agree with CMfgE1 in that companies should know what information to provide you. Frankly, they should know what the print asks for, what they need to produce the part to print and other related specs. Anything beyond that should be clearly stated somwhere else like the RFQ or...
I think what you are asking is why do shops ask more for +/-.002 location vs. +/-.005, when the parts come out dead nuts anyway. The only thing I can say is that when you see a +/-.002, you will start planning accordingly, and depending on the material, feature, location etc, that may add...
