annoying dull drill bit

[JonathanF1968]

A drill bit is driving me crazy. It's a 10.5 mm "metric high speed blank" from Exotic Blanks. Nothing special; not parabolic. But for some reason, I can't get it sharp with my Drill Doctor 500. (I've successfully drilled say a dozen hardwood blanks with it.) I think I've sharpened 1/4 inch off it at this point, but it's not cutting. I'm trying to end-drill through a 2" ebony blank that was predrilled at 7 mm. But it's smoking almost immediately upon touching the wood. And it's even resisting going through a pine 2x4 with a regular hand drill. Other bits I've sharpened seem to be fine. It's at 118 degrees. Not sure what's up....

I'd actually buy a parabolic bit at 10.5 mm if I could find one, but that size seems elusive.

 

[Sylvanite]

Check the twist on the drill bit. It may be different than a standard jobber bit. If so, then the drill doctor won't get the relief angle right. I had the same issue with some cobalt bits. They wouldn't sharpen properly until I changed the way I inserted the bit in the carrier. Try twisting the bit in the carrier to see if that changes things.

I hope that helps,
Eric

 

[JonathanF1968]

I am twisting the bit in the carrier. I think there is some user error going on here. I just ruined another bit, 7 mm., different type, in the Drill Doctor. Made it go from a little dull to totally unusable by sharpening it. I don't get it. My sharpening process is:

1. Set bit in the chuck, snug but moveable.
2. Align chuck dot with where you set the bit depth. Release the jaws, move the bit until it touches the back, then close the jaws. Remove chuck from depth setter and tighten.
3. Switch it on, then align the dot with the pole of the sharpening hole (which is set to 118) and twist it, with each switch of dots a half turn. It should be about 6 turns (12 half turns) to sharpen a bit. But at the end of that, it no longer will drill a hole.

Oh boy am I frustrated....

 

[JonathanF1968]

Check the twist on the drill bit. It may be different than a standard jobber bit. If so, then the drill doctor won't get the relief angle right. I had the same issue with some cobalt bits. They wouldn't sharpen properly until I changed the way I inserted the bit in the carrier. Try twisting the bit in the carrier to see if that changes things.

I hope that helps,
Eric

I'm not sure how you mean to change the way it is inserted into the carrier. Do you mean how the twist aligns with the guide dots?

 

[carlmorrell]

I had that happen a few years ago. The drill bit looked sharp, and it was, but somehow the clearance angle got changed. So the sharp edge of the drill bit was not meeting the material first. It was riding on the surface and not cutting in. It was some adjustment on the drill doctor had gotten off. I suggest rechecking all the adjustments.

 

[Woodchipper]

Interesting post and replies for a solution. So far, I haven't had a problem with drill bits but the day isn't over. Reminds me of bits that could stand sharpening on the Rikon grinder; has a platform that aligns the bit against the wheel.
Humor-
Me: This is driving me crazy!
Wife: Won't take much gas!

 

[Smokey S]

I was a machinist for the first 23 years of my career, started in an apprentice program in the early 70s. Always have sharpened drills by hand on bench grinder, never have used a drill doctor. As mentioned already, a must to have relief behind the leading edge. Get in some good light with the drill held up in front of you. When looking at the leading edge, you should see the relief falling off. I am sure you can probably pull up a you tube video on sharpening drills. Just saying…..Smokey

 

[randyrls]

Use a sharpie to mark the cutting edges. Touch the bit tip gently to the wheel, twist twice and look at the bit tip. If the mark is all gone OK. Mark the bit again and drill about 1/4" into some wood. Check the bit. If the mark is still on the cutting edge, then Carl's observation is correct.

There is an entire industry devoted to drill bits and sharpening them. MSC Industrial Supply aka MSC direct, has a warehouse about 30 minutes from my house. When I need a bit or bits I put a "will pickup" order in. An hour later I can drive there and pickup the bits.

 

[Woodchipper]

Fastenal also has sharpening service. Know of one customer who bought bits and had them sent to be sharpened before taking delivery.

 

[JonathanF1968]

I was a machinist for the first 23 years of my career, started in an apprentice program in the early 70s. Always have sharpened drills by hand on bench grinder, never have used a drill doctor. As mentioned already, a must to have relief behind the leading edge. Get in some good light with the drill held up in front of you. When looking at the leading edge, you should see the relief falling off. I am sure you can probably pull up a you tube video on sharpening drills. Just saying…..Smokey

YouTube was my first stop, but I couldn't find anything specifically addressing this kind of issue. I did watch about six videos of people show how to use the Drill Doctor.