I have a drill doctor. I've noticed that if the drill is abused, so that the rise along the flute edge is ground down. Darn bed angle. The drill has to be sharpened down enough to get a clean edge on the flute. That can take sometime even in a DD. Grinding off the the tip is an option, but I can't hand sharpen to begin with. That's why I bought the DD. I don't abuse my drills anymore, if I have any doubt about it's cutting, I put it in the drill doctor.
Larry
