On Tue, 21 Nov 2006 17:58:44 +0000, Toller wrote:

"zap" wrote in message
ink.net...
You are missing something, and that something is VERY Important.

What you would end up with would be a drill which would not drill into
even butter, and would burn up if you tried to drill into anything harder.

On a properly sharpened drill bit, only the cutting edge touches what you
are drilling into. That is, that cutting edge extends further out than the
back of the flute that the cutting edge is on. The cutting edge is the
front edge of the flute, and the back of the flute must taper away from
the leading edge. If it does not, then the entire flute rubs and will not
cut.

Like a knife, the cutting edge must be at such an angle to what you are
cutting to dig in, while the side of the knife would just slide over
without digging in to make the cut. The leading cutting edge of the drill
bit works the same way.

The drill sharpening guides are made to automatically cause that angle to
be ground on each flute of the drill bit evenly, and all flutes of a drill
must be at the exact same level, else only one will cut and the other not
touch.

My first job involved drilling little holes into stainless steel. The drill
didn't stay sharp very long, so my first skill was to learn to sharpen them
on a grinder, getting all those little undercuts just right.
Ah, but that was 35 years since I last tried.
How does the machine do it; I thought it was just a simple grinding wheel,
but there must be more to it than that.

If you're talking about the Drill Doctor the chuck has a cam--as you
rotate it it moves the bit in and out to as to have the flute properly
ground.

Buy the drill sharpening tools and be happy with the results.

Zap

RayV wrote:
A while back I had to drill out a bolt and went through several bits.
Dulling them, snapping them and as a bonus I also snapped a misnamed
easy-out. Buy new bits? Nah, they cost too much for a decent set
besides I have probably 100 drill bits. I gotta figure out a way to
sharpen them.

DAGS. Keeps coming back with buy a drill doctor. I find the thing
from Lee Valley and others that holds the bit at the correct angle to
bench grinder for $10.
http://www.leevalley.com/wood/page.a...072,43086&ap=1

The DD and the angle guide don't seem to be doing anything fancy so I
think why can't I just do it myself. Here's what I'm thinking please
tell me if you think it will work.

Cut a wedge at the proper angle
Chuck the dull bit in my drill press
Clamp the wedge and a stone or fine file to the DP table Lower the
dull bit against the stone or file Keep bit oiled and cool Done

Unless I'm missing something doing it that way would give me the same
results as the grinder jig and probably the DD too.




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