Need help: drilling w/ carbide bit

S

SteelDriver

Joined
Jan 28, 2002
Messages
790
I'm drilling through hardened ATS-34 with a straight flute solid carbide bit and it's going much slower than I anticipated. The stock is 3/16", bit diameter is 5/16", 700 RPM, light pressure, lots of Cool Tool II. The bit is not producing chips or metal splinters but rather seems to be grinding away and coloring the Cool Tool a dark gray. I've been drilling for maybe 30 minutes and I'm not even 1/4 through. The bit is new and felt sharp when I checked it a few minutes ago. It's not overheating either, I'm sure of that.

Am I missing something here, or is it supposed to take a *long* time? :confused: Any help is appreciated!
 
You should run carbide bits at high speed. They chip through the steel rather than cut like regular bits. I know it's been beaten to death but I gotta say it anyway, be sure to wear eye protection, those carbide bits can shatter and fly all over the place. Your sight is worth a little discomfort!
 
A straight flute bit is not designed for plunge cuts, they are for side milling, get a end mill that is designed for plunge cuts. Carbide bits will cut very well at low speeds reducing the need for coolent and will extend tool life. I never run my bits faster than 500 rpm, I cut without coolent and may tooling stays sharp.
Leon
 
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