Drill doctor question

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Dale Allen

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Oct 27, 2012
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I was given an old model of this tool but from what I can tell the method seems similar to the new ones.
When I look closely at my untouched drill bits, split point and other, the cutting surface looks to be ground flat and tapered so the cutting edge is raised.
When I run one through the paces on the drill doc the cut surface is rounded.
Is this the way the tool sharpens them?
Seems to me it leaves the very edge unable to do it's job.
Or maybe I'm helplessly lost with this tool!

Dale
 
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duncsuss

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Sounds like you don't have the bit correctly angled in the clamp. At the same time you set the projection, twist the bit until the spring clips snap into position in the flutes of the bit. That orients it so the cutting edge of the bit is the highest point after grinding.
 

Dale Allen

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I have been able to sharpen bits with this machine and they are better than dull.
What I'm asking is about the shape of the grind.
 

leehljp

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I don't know what the cause is, but for some reason it sounds like the grinder itself is dull or mis-shaped
 

duncsuss

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The grind of my Drill Doctor is slightly curved, as opposed to being a flat surface.

The leading edge (the part that does the cutting) is the highest point. Behind the cutting edge, the ground surface falls gently away, getting a little steeper the further away you get from the leading edge.
 

randyrls

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Feb 2, 2006
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Harrisburg, PA 17112
I have been able to sharpen bits with this machine and they are better than dull.
What I'm asking is about the shape of the grind.
Dale; There is an entire engineering spectrum of drill bit shapes. The cutting edges on good quality bits are shaped by multi axis grinding machines They are not flat in any direction / dimension.
This is a sample of the various geometries
 

Mortalis

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Aug 19, 2013
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Rochester, Mass
I bought a drill doctor a couple years ago to keep my drills in shape. I never did like the way it replicated the sharpening process (maybe I just didnt use it often enough) and the diamond coated wheel IMO is too coarse.
I used to work for a company that manufactured rotary cutting tools that included drills but never learned from the old timers how to hand sharpen. Instead of using the 6 axis grinders, they would touch up an edge by using a standard bench grinder with a B&L stereo microscope (they would sharpen .005" and larger drill points). Twist and advance. That is the process used by the drill doctor.
 
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