By the way,..run the drill slow and keep a dab of dark thread cutting oil on it when you're drilling.
Run it too fast and it'll work harden the steel you're trying to drill through. D2 is especially tough to work.
What he said. Try drilling no faster that 50 SFPM. * Also try hand sharpening them to around 118 Deg included angle and splitting the point. You can sharpen a drill by hand better than a drill dr will do it. If the chips are blue you are turning the drill too fast.
* SFPM = Surface Feet Per Minute. To calculate SFPM it is the recommended cutting speed times four divided by the diameter. That would be in this case SFPM = 50 times four /divided by drill diameter. Say for a 1/4" drill it would be 50X4/.25 = 200 RPM.
