I think the difference between split point drills and the 4 facet grind is
that the 4 facet method is just 4 flat grinds, there isn't and crown in the
cutting face relief, and without split points, there is still the small
chisel edge at the web.
In all the years/decades of developing drill sharpeners, the tooling
companies haven't come up with a decent drill sharpener that's affordable
for the part-time tinkerer/home workshop users.
Some Drill Doctor owners will probably argue that, but I've read the
complaints of many stating it works OK some of the time, on certain sizes.
I don't like the little General fixture mentioned earlier, because the
little twist indexing finger isn't a good feature. That's the little pointy
adjustment located under the V (only the worst place for it).
The little General fixture makes a great relief grind as it swings, but it
will make it anywhere on the end of the drill. So ya play and adjust and try
a few grinds, then play and adjust some more until it's leaving the
narrowest chisel point, but ya start over as soon as you try another size
Besides that problem, the only sensible way to mount the General fixture is
on a slide or a mount that allows it to be moved toward/away from the
grinding wheel and held in place. Bolting it to a fixed point as suggested
in the instruction sheet, sucks.
I'm fairly certain that you already realize the basis of these comments DoN,
but I'll add them FWIW.
As the point is ground, the angular rotation of a drill needs to follow a
fixed point on the fixture that has a relationship to the twist spiral. Just
moving a drill toward the grinding wheel without following the twist will
change the orientation of the chisel point.
If the fixed point on the General fixture was on top where it could be
adjusted easily, that would be tits.
With a conventional grind on a drill, maintaining the narrowest chisel point
(at the web) is the key to having a drill that cuts and feeds easily, and a
drill that may only rub a hole in something if enough pressure can be put on
The key to attaining the narrowest web/chisel point width is a fixed point
that causes the advancement of the drill to follow the twist.
A while ago, someone was looking for the identity/maker of a drill grinding
fixture that was made by Delta (Rockwell/Delta, maybe). It was a couple of
arms and a few adjustments with scales which takes up quite a bit of space
just to mount the fixture.. considerably more than a sqare foot of space,
not including the bench grinder it gets mounted to. You probably need a
workspace about 24" square to operate it.
I have one that's similar to the Delta that was made by Kalamazoo, but I
haven't used it yet, since all my stuff is waiting for me to locate a new
It's got a long sweeping arm and a scale or two, but I suspect that it's
performance will depend upon some futzing around too.
It's beyond me why some tool maker hasn't developed a drill sharpener that
is as easy to use as zing, rotate, zing for the trailing side grinds, then
insert, rotate, lift, rotate and it produces a resharpened drill that as
good as factory fresh new.
Beyond me, besides the fact that there aren't many small tool manufacturers
That's all the motion that the machine shop drill grinder needed to produce
perfect split point grinds.
I realize that a single drill holder won't suffice for all the sizes up to
3/4", it's just not realistic, and a large portion of the value of a real
drill sharpener would be in the precision drill holders.
I've pondered how to make a round drill holder resembling a drill chuck for
quite a while, and haven't come up with anything better than modifying a
drill chuck. Snugging the chuck jaws against the drill flutes could cause
chipping, so gripping the shank would likely be a better approach.
Supporting the drill near the point presents another challenge, since
bushings for every drill size would be problematic as far as time consuming
to make and/or expensive to buy. Something like a camera lens iris might be
If large drills are to be resharpened, then a small drill chuck would need
to be adapted/adaptable upward in size to fit in the same place as the big
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