[AT] Drill bits for drilling our old tractor steel and iron.

[Stephen Offiler]

We have an older Darex sharpener.  It looks nothing like anything on their
web site, but my sense is that it was on the medium end of their spectrum
when it was new, and perhaps a $2000-ish machine.  Not counting myself, we
have one guy who's pretty good, but that machine boggles everyone else's
mind.  It's critical to get the drill properly aligned rotationally in the
collet, and that alignment itself requires two adjustments to the alignment
fixture.  One is for drill diameter, and that one is odd because the scale
on the fixture is somewhat non-linear, which throws some people.  The other
is for back-rake angle.  That "flat" surface behind the cutting edge has to
slope away slightly or it drags on the bottom of the hole creating heat.
That adjustment is also difficult because it uses the drill point angle as
a variable.  118 and 135 are common but we have some drills that are 130
and BOY does that make a big difference getting those adjustments right.
Our guy who I describe as pretty good always assumes those 130's are 135,
or he believes that 135 is "close enough".  Wrong.

Of course, the mechanism that supports the collet against the grinding
wheel must have the correct point angle too.  This adjustment is the only
one that makes intuitive sense to anybody, but the difficulties I'm talking
about above are in the pre-work to get the drill aligned in the collet in
the first place.  Get it right and you can make an edge nearly as good as
the factory.  Get it even a little bit wrong and you're out in left field.

We have one specialty job that uses a drill resharpened to a 90-degree
point.  I am the only person in the shop that can do that drill.

SO


On Fri, Oct 25, 2019 at 10:58 PM Spencer Yost <spencer at rdfarms.com> wrote:

> Hey Cecil,
>
> When I first got the drill doctor I could not get results I expected. It
> was close but still not what I expected.  I kept thinking it was the
> machine but after several friends continue to swear by them I finally
> decided it was the operator :-)
>
> I went to their web site and viewed several of their videos and realized
> there was a small trick I was missing. I wish I could remember what it was.
> I think it’s the orientation of the bit during that initial set up when you
> set the depth in the chuck.  Whatever it was I remember being pretty easy
> on myself because the manual was not clear on it.
>
> Anyways maybe go back through some of their videos and some of the other
> folks‘ YouTube stuff and make sure you’re doing everything.   I wasn’t and
> am much happier now.
>
> Spencer
>
> Sent from my iPhone
>
> On Oct 25, 2019, at 3:20 PM, Cecil Bearden <crbearden at copper.net> wrote:
>
> 
>
> <...snip...> I have had a couple of the Drill Doctors, but gave up on
> trying to get them to sharpen a bit correctly. I just use my eyeball...
> After 50 years, it is not too hard.  I do have a drill grinder for bits 3/4
> and larger.
> Cecil
>
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