Doug--
I have a drill doctor and have had the same experience with it that you have.
It doesn't produce a decent clearance angle. All it can do as designed is to
produce an approximate zero clearance angle. That's because it rotates the
drill about it's own centerline. What really is needed is rotation about a
diffrent center at an angle to the drill centerline.
When I hand sharpen a drill to get the clearance I twist it in my fingers and
at the same time lift the back end of the drill in a wide curving motion to
get the right clearance. I seem to have to relearn this each time I have to
sharpen a drill. Sometimes it takes me several tries to get it right
depending on how calm a mood I'm in. On larger drills say over 5/16 or so the
drill doctor gives me a nice starting point from which to work especially if
the drill is pretty bad to begin with. Then it's a lot easier to do the
clearance angle motion.
By the way, I use a green carbide wheel for this final dressing of the cutting
edge of my drills. Supposedly these green wheels should never be used on
steel, but it works real nice for me.
On small drills under 1/8 I use magnification and have even set up a dremel
tool under my 10x-30x microscope for real tiny ones over #60.
A microscope is great for checking tool edges and a lot of other things in the
shop. (Spark plugs, bearings, worn screw threads, machining burrs) Good ones
are pricey, even used. Just keep your eyes open. Watch ebay to get to know
the going street prices. I paid $300 plus another $50 for eyepieces for the
good Nikon binocular scope that I keep on my desk. My little "no name"
binocular microscope out in the shop was a swap meet find at $40. Came off of
some kind of machine shop setup. Took some cleaning up and I had to build a
stand for it.
Ed Weldon
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