spaco wrote:

From time to time I have had real trouble sharpening SOME drill bits on
my Darex Drill Doctor. I thought I understood it pretty well.

As others have done, I have 2 complete indexes of "Import" bits. I use
them for general work, always replacing them with high quality bits when
the originals fail. (surprisingly, some of the larger sizes do seem to
hold up pretty well).

A couple of days ago I had to drill a couple of #16 holes in some
pretty hard steel, the tang of a knife. First I grabbed a Chinese bit
and it dulled real fast. Then I grabbed a USA HSS dril bit. It drilled
one of the holes and part way through the other before heating up and
dulling.
When I took the Chinese bit to the Darex, I noticed that it was badly
dulled and I couldn't get the angles right. Somehow, it just didn't
look right down in the Drill Doctor cavity where the two little fingers
grab it. I tried several times, but no luck.
The HSS bit sharpened right up with correct angles and I completed
the job for my friend.
After he left, I tried to figure out why I couldn't seem to get the
Chinese bit to sharpen correctly. Finally, I realized that the back
of the "land" had less material in it than the USA bit. These Chinese
bits even feel funny when held in the hand. They feel "skinnier" in
back of the actual cutting land.
This causes the grinding angle to be off a LOT when you transfer the
bit from the locating port to the grinding port. I tried to rotate the
locating collar CCW, but I gave up after several tries and just hand-
sharpened it.

I checked several bits and see the same sort of problem, at least with
the smaller bits, but in no way do I have enough data to tell how
extensive the problem might be.

I put an image of a drill bit on my website to try to show this problem.

Go to:
http://www.spaco.org/BadDrillBits.jpg
The RED areas show where, IMO, metal is missing from the back side of
the land area.

I'd be interested to hear from others who have had similar experiences
or could shed light on the problem.

Pete Stanaitis
--------------------------------------


This is a problem that is as old as the drill doctors.

It comes down to being a failure to be willing to experiment in spite
of the results of following the instructions, several times in a row,
not working out.

Drills are different. Experiment. Twist the drill forwards or
backwards from the setting suggested in the instructions and look at the
results.

If you bought a $5000 sharpener, you would still have to deal with
variables in different manufacturers drill bits.

Check The Drill Doctor site. There was a run of the early ones that
had some issues. They had a recall, or at least were trading in the old
ones. shrug A bud had one of the old ones when it was new. If you
folowed the instructions exactly, and refused to deviate from them, it
either worked or it did not. If you looked at the drill bits, and mad e
adjustments as required, as indicated by the results, it worked very well.

Adapt! :-)

Cheers
Trevor Jones