Sharpening Auger Bits

[jmellc]

It seems I am on a roll with drill bits lately.

Does anyone know a consistently reliable way to sharpen auger bits? I just dulled a good one yesterday. I drilled 10' deep or so, then hit cinder block. I have had limited success before with a rat tail file so I tried that. No luck at all. I know to sharpen only in the direction of the cut, otherwise even a sharp edge will not bite the wood.

I have 2 fairly new but dull bits and my boss probably has 25-30. At $25 and more a bit, this adds up.

 

[brichter]

Lots of good uTube videos on the subject. I have a special auger bit file I bought from Lee Valley.

 

[jmellc]

Lots of good uTube videos on the subject. I have a special auger bit file I bought from Lee Valley.

I've looked at this site and seen their video. I may order the file and try it. Only thing I wonder about is that they seem more geared to woodworkers. Their video showed brace auger bits used on wood projects. I'm sure they do not get the abuse our auger bits get from hitting nails & masonry.

 

[GoldDigger]

I've looked at this site and seen their video. I may order the file and try it. Only thing I wonder about is that they seem more geared to woodworkers. Their video showed brace auger bits used on wood projects. I'm sure they do not get the abuse our auger bits get from hitting nails & masonry.

A lot depends on how the cutting surface of the bit is hardened.
Wood cutting bits have a relatively soft steel which can be sharpened with a file.
Carbide or even just heat/surface treated bits designed for more demanding use may require a grinding wheel or stone instead, or just not be resharpenable.

 

[macmikeman]

I have had success with using a teeny grinding wheel and a dremel tool , but it didn't seem to last for very long once I got it sharp again.

 

[GoldDigger]

I have had success with using a teeny grinding wheel and a dremel tool , but it didn't seem to last for very long once I got it sharp again.

You may have removed the locally hardened part of the bit surface, restoring the shape but not the metallurgy.
Or you may just have overheated it during the grinding process (more likely to happen with a large wheel and heavy pressure...)

 

[al hildenbrand]

I like the dremel and grinding wheel approach, as well. I've been doing it for my bits for a decade and a half with no complications.

 

[J.P.]

I just use a half round file, Kind of large one that I use with rigid and large conduit. It takes about 10minutes, Like you noticed they don't last as long once the factory edge is gone.

 

[jmellc]

Thanks for the feedback. I don't yet have a Dremel tool but will start saving for one. When I get a new bit I am usually good about keeping it in the plastic tube after use and keeping it from rolling around with other stuff. I do good with it for awhile anyway, then the tube gets lost or cracked.

 

[jmellc]

Well, I bought a Dremel chainsaw bit the other day and tried it in a battery drill. It helped a fair amount with a bit that had been mangles by nails/masonry. I will also try it on some older bits when I have time.

 

[mopowr steve]

Dremel or actually I have a Milwaukee cordless with reinforced grinding disk. Works great as long as your grinding the correct face of your bit.

 

[Nom Deplume]

Nothing beats a properly sized file.
you guys are looking for the lazy way out.

 

[delectric123]

Nothing beats a properly sized file.
you guys are looking for the lazy way out.

How does a guy decide what a "properly sized file" is?

 

[Nom Deplume]

How does a guy decide what a "properly sized file" is?

Just a little narrower than the flat cutting edge.

 

[George Stolz]

Nothing beats a properly sized file.
you guys are looking for the lazy way out.

Agreed. While the bit is still warm and starting to show wear, whet the edge back on with a XX slim file and return to drilling. Takes a couple seconds if you keep up with it, and let the bit do the work while you're drilling.

I have learned to avoid the Greenlee self-destructing Nail-Eaters like the plague. If they don't happen to self destruct in the first few minutes, they are also a PITA to sharpen. Lenox 7/8" augers are still one piece construction and hold up decently in the right hands.

 

[rlundsrud]

grinding

grinding

I personally prefer a bench grinder but there are several things that you would need to understand before proceeding. It very important to use light pressure and dip the bit in a water bath at regular iintervals to keep the edge cool. Nothing ruins a bit more completely than overheating, it softens the metal and it will never hold an edge again. The second thing you need to understand is the clearance angles that must be maintained. If you have a fairly sharp bit, keep it next to you when you grind the dull one and use it for comparison. Finally you need to keep the two leading edges 180? apart. If you overgrind one of the edges it will be slightly lower (if you look at its profile) than the opposing edge while cutting. You already mentioned the importance of sharpening into the leading edge of the cutter but I would be remiss if I didn'tmention it. This same process work for drill bits as well, I would start with a small one as they tend to overheat quickly but with practice you will be a pro in short order.

Bob

 

[cowboyjwc]

We have a sharpening place here in town that will do them, but I always used a file. Once you've sharpened the angle, go to the back side and just run your file over it to remove the burr.

 

[gadfly56]

I suppose that if you ruin the hardening by grinding the edge too hot you can always re-harden it. I've no doubt there are a truckload of YouTube videos showing you how.

 

[CFL]

Like others have said, just use a file. It's way faster than a grinder or dremel or whatever. I can make a bit last for months. That's probably about 25 rough-ins. The easiest way to do this is to drill through a stud or two at a comfortable height and rotate the bit to the desired angle. Then you just run the file across the cutting edge until it's sharp.

Once you get a pile of them that are beyond repair with a file, take them to a pro. I have a saw sharpening shop near me that will sharpen each for about $5.00.

I think Irwin has instructions on their website. I was looking on some website a few weeks ago, if it wasn't Irwin it was another major manufacturer.