Sharpening Drill Bits?

[AlaskanHunter]

In this thread http://www.bladeforums.com/forums/showthread.php/1369222-Are-drill-doctors-worth-it-for-carbide-bits several guys mentioned that they sharpen their drill bits on a grinder. Would any of those fellows be willing to step forward and offer a tutorial on how to do it correctly? I know the rudimentary basics- use grinder to restore factory shaped edge without overheating the bit- but fail to produce consistent results. 70% of my attempts result in worse than before performance, 20% between factory new and dulled state, 5% broken, and 5% as good or better than new. What can I do to produce more consistent results?

 

[JPuri]

Hi!
What i did is make a mask with a junk piece of steel with the angle on the tip of the drill bit

something like this
https://www.google.com.ar/search?q=...UIBygB&biw=1600&bih=735#imgrc=_HeeADQPFQZCfM:

of course you won't be able to sharpen a 1mm drill at the beginning, but with some practice you will!

 

[Navin_R_Johnson]

I think this is a case where watching a few of the tube videos would be more beneficial than trying to describe how to follow the angles needed.

Start with large diameter old bits that are ready for the scrap bin and work your way down to the smaller bits when you get the hang of it. I don't bother with bits under 1/8" (3mm) and just replace them if they need more than a simple touch up.

 

[Wowbagger]

The problem is you are trying to do something BY EYE that was originally done on a precision machine tool bit grinder and expecting the out come to be to a tolerance of less than a thousandth.

Yes there are those that can do that, and I even get lucky occasionally,

Buuuuuuuuuuut
Why not just get yourself a little precision drill bit sharpener and
Reeeeeeeeelaaaaaaax ?

Yes it is fun to sharpen by hand and get it to finally work but the amount of effort involved may not be worth it.

As far as copying factory grinds . . .
now hear this :

They often are not accurate enough to make a GOOD cutting bit and can be MUCH improved by careful honing specifically just behind the edge where OFTEN that area touches the work before the cutting edge and causes the edge to not cut at its full potential if the geometry were spot on.
also
sharpening by hand, and this is where the need for close tolerances comes in . . . one edge is almost certainly higher or at a different angle than the other and so may just be going around but not cutting . . . hence little chips instead of long ribbons or one ribbon instead of two.

SHARPENING JIGS ARE COOL !
and very useful.

At the very least get a jeweler's magnification visor and a magic marker to black the end of the bit to see where it is actually rubbing or cutting against the work when in the drill.

 

[Wowbagger]

Start with large diameter old bits that are ready for the scrap bin and work your way down

I agree with starting with large bits.
The rest of this suggestion made me think of a new approach :
Try a brand new bit that you have that just doesn't quite cut well. That could be about any brand new bit off the peg at the local store. Not cutting well is when you have to bear down or you get one ribbon rather than two or , assuming this is your plane old variety bit, you get no ribbons but just dust or chips.

Mark the bit with magic marker, drill with it again, then look to be sure that the area where the magic marker is gone is on the bevel that contacts the work and is just near the edge and up to the edge. The area 1/32 or so back from the edge should still be black and there should be no black at the very edge. Doing this will teach you what you are trying to create on the scrap bin bits.

PS: I routinely hand sharpen, using diamond paddles and the jeweler's visor, bits down to 1/16 (1.5mm) but then I use a lot of those (and bit larger bits) to make pilot holes for the larger bits and or Unibits. ahhhhhh unibits now there is a glorious thing if you drill thin stuff but alas another thread.

 

[Wowbagger]

I forgot to be clear : if the bit is rubbing behind the edge but the edge area is still black or you suspect the edge is not cutting well then grind BEHIND the edge and or up to the edge until the edge contacts the work but the area behind is ground away and so is out of the way.

I hope that makes some sense.

PS: if you take off too much material behind the edge it chips and or breaks as you have experienced.

 

[12345678910]

In this thread http://www.bladeforums.com/forums/showthread.php/1369222-Are-drill-doctors-worth-it-for-carbide-bits several guys mentioned that they sharpen their drill bits on a grinder. Would any of those fellows be willing to step forward and offer a tutorial on how to do it correctly? I know the rudimentary basics- use grinder to restore factory shaped edge without overheating the bit- but fail to produce consistent results. 70% of my attempts result in worse than before performance, 20% between factory new and dulled state, 5% broken, and 5% as good or better than new. What can I do to produce more consistent results?

See my post in that thread

http://www.bladeforums.com/forums/s...h-it-for-carbide-bits?p=15772472#post15772472

Eyes open, click em if you see em.




Start with a 3/8" drill, it's easier than a 1/8" drill because you can see it.

 

[Nathan the Machinist]

If you can grind a knife, you can sharpen a drill bit. Try harder.