46 comments on “Sharpening a Auger Bit

  1. Thanks Paul for this one, it is coming at a great time as I need to drill some holdfast holes on my new “Paul Sellers” style bench this weekend. I have an old set that needs attention and have never done this before.

    And by the way I thoroughly enjoy the Woodworkingmasterclasses and your Blog.

    Thanks for everything.

    Steve

  2. Paul

    I have a couple questions that I was hoping someone could provide some clarification for.

    1.) You mentioned that the diamond hone is eze-lap. Is it the 1200 grit fine or the 600 grit medium?
    2.) Are there instances in which you would use the coarser grits of diamond hones since Lee Valley Sell a set of four together or do you mainly use the finer grits if that makes since?
    3.) Do you see any advantages in the dedicated auger mill files or do you always just use the triangular file.
    4.) When you sharpen the bevel and start at the heel, you mentioned chasing the heel to not make the angle to steep. What angle do you try to maintain on the bevel the standard 25°-30° or shallower?
    Okay thanks again for this video It was extremely helpful.

    • Answers to above:
      1 and 2) Auger bits don’t really need the sharpness of a chisel edge or plane. You could use coarse even at 250 and that will work fine. I would use the medium at 600-800. That’s plenty and will cut the steel fast.
      3) I have never used and auger mill file because the saw files work so well.
      4) The angle makes little difference unless you go too steep. Then it gets harder and harder to sharpen. Sharpening should always be maintenance and never restoration, which shows neglect

  3. Excellent!! Best done video I’ve seen on sharpening auger bits. I’ve just started using auger bits – bought a bunch at an estate sale and using a brace that I’ve had for a long time. Auger bits really do work nicely. Been having great fun making sawdust lately!!

  4. I basically knew how to sharpen auger bits learnt when doing city & guilds carpentry and joinery long time ago.
    Paul’s explanation and the reason for what he dose is first class.
    I have used saw files and credit card style diamond Plate.
    I do like the look of those little Ezelap files may have to invest in a set.

    • David,

      I picked up a great 10″ brace and a complete and sharpened set of bits sizes 4-16 (1/4″-1″ as far I can tell) on ebay. They cost me about $95 USD which is probably more than I could have spent, but it looked like a really nice set and I was in a hurry. Buying them together as a complete set was a convenience for me and I don’t regret it at all because the set is complete, beautifully sharpened and in great condition. Although I have all the sizes, the set was cobbled together with augers from a couple different manufacturers. I’ve be trying them out over the last few days and they are a joy to use. So far, I’ve bored many holes just so that I could experience the tool and get the feel of each bit. They make such clean holes and have all the benefits that using hand tools in generally have. If you have the means, I would definitely recommend you get some. I’m confident you can put a set together for less money than I paid. I wish you luck and I hope you enjoy yours as much as I do mine.

  5. Fantastic! I just came in from my shop where I was using an old brace and bit and the auger made a terrible job of cutting; splinters front and back. I happened to look at my e-mail and voila! another great sharpening demonstration from Paul. I’ll head back out and sharpen the bits and look forward to the nice clean cuts. Thanks Paul, talk about great timing!!

  6. Very simple and very effective. Great job of instructions as always. I recently picked up a set of auger bits from a local antique store. The price was right but after I got them home and got a good look, they may not all be salvageable. But I will use this technique and see how many can be saved. Thanks for the video!

  7. Hi Paul, I’m fairly new to you’re band of followers. I’ve built additions and houses and rehabilitated buildings all my life and know the need for accuracy and attention to detail. Nearing retirement , I have recently taken interest in fine woodworking and I must say it’s a different world. I find your style of instruction so simple and easy to follow I’m beginning to think that even this old dog can learn some your new (OLD) tricks. I look forward to many new learning experiences with you. Thank you, Ken

  8. hi
    Paul,
    I’m a new member to your site and must say it is MOST appreciated! I’ve been working in wood and making small and large pieces now for about 4 years. I am a “hybrid” worker, as I find myself to be more and more using hand tools.

    Your kindness in sharing your knowledge, and this video will allow me to take my Dad’s bit brace out of the drawer, hang it in my tool cabinet, and use it. Thank you again, and I look forward to watching and working with you to hone and broaden my woodworking.

    CHEERS!!

    GerryR Hereford, AZ

    ” A really good woodworker knows how the hide his / her mistakes.”

  9. Paul,
    I have a Stanley No. 129 adjustable bit. The leading edge of the cutter is concave. Would it be reasonable to use a fine rat tail file on the leading edge of the cutter or should I consider something else?

    Thanks for sharing your knowledge!

    Darrell

    • You can still use a flat or triangular file for this. The hollow grind is just a method used by Stanley, but by the very cutting edge there must be a flat anyway as all hollow grinds must be refined with a flat to form the angle.

      • I am confused about this. I just bought a used Stanley adjustable bit (very large diameter, to go with my set of Irwin fixed-size auger bits). The adjustable piece has the spur, and a cutting edge. The bottom of this piece (in the direction of boring) is flat. The concave side of it has the scale (marks with diameter settings) on it. Is it this concave face (with the scale marking) that gets sharpened with dowel + wet and dry?

        On mine, the flat (bottom) surface of this piece has very rough machining marks on it, and has obviously never been sharpened. This surface would be the equivalent to the the back of a plane iron, so there is some incentive to dress it a bit too. However, this might interfere with how it mates to the central cutter & snail piece.

        So do I sharpen both?

    • Best to shape a piece of wood or find a dowel similar to diameter of curve and wrap fine wet n dry around it. Depending on how badly the edge is rounded will determine which grit you start at. You don’t need to go past say 600 grit.

  10. Here is a page describing various kinds of auger bits: http://www.theluddite.com/auger_bits.html . I have a auger that will not enter the wood past the snail, but is shaped differently from that which Paul shows. I suppose this must be a sharpness issue and, staring at the bit, I don’t see how it can ever work so I was looking for pictures of different auger types.

  11. Do you have a preference for Irwin- or Jennings-style bits? From what I’ve read, it seems like Jennings are preferred for hardwoods, but you usually have something to say about “conventional wisdom,” and I noticed that the bit you show is (I think) an Irwin pattern.

    • Jennings and Irwin are different twist patterns. jennings was considered the better of the two. Irwin is what we call fast cut. they work fine and i can only see one difference and that is you have a tighter spiral that gives more support as the spiral of the bit deepens in the hole as the whole is progressed. The Irwin has a long spiral which allows the waste to evacuate more readily.

  12. At 9:00 what is the back edge? I was thinking the other “side” of the cutter but it doesn’t look like that is what is being filed when Paul says “back edge”. It just looks like he moves farther towards the snail on the same side / edge to me?

  13. Paul –
    All well and good – but what happens to a #1 (a 1/4″ bit or smaller?) my xx-slim taper 3 corner file may “fit” but there is not a lot of filing “action” going on – suggestions?

  14. I have admired the wood sawtooth pattern board hanging on the back wall (frame right) in many episodes now. I imagine this is a teaching tool. In this episode, a second one appears with teeth cut in two directions.

    I have not seen these used in any videos. Please consider giving us a closer look – especially the second, more complicated one. I’m finding it difficult to visualize sharpening that profile.

    • See 2 videos in “Tool and Technique” section, one on saw sharpening and one on re cutting saw teeth … seems to me he uses the cutouts for explanation of tooth patterns in one or both videos.

  15. Finding this video on the site came at a very good time for me. I’ve acquired quite a few auger bits but only a very few of them are sharp and was getting ready to work on cleaning up and sharpening the lot.
    Really enjoy and appreciate all of the down to earth details in the way you present things.

  16. Great video and information, as usual! Thanks for this. I do have a question regarding working on the flat bottom of the cutting edges. You mentioned that part of it needs to be lower to provide relief for the cutting edge. Were you referring to the area near the spur being lower than the part near the snail, or is it the cutting edge being higher than the rear heel opposite the cutting edge? Just trying to make sure I’m not going high to low from the snail outward when I should be going high to low from the cutting edge back toward the heel as it begins to go up the spiral. Thanks for any clarification.

  17. Hi Philip,
    I think I have an answer for the blunted snail threads. I have used a thread restorers file and it usually works, you can find those in the metal cutting tools of a hardware store or contact a company that sells tools to auto mechanics.

    I have also found that a small triangular file works also. If the thread is very close to the base ( sometimes called the root) of the screw it’s too far gone to do anything with it. The best way to do it is to hold the bit in the vise and sit down if you can, you want to be in a relaxed position so you can concentrate on the filing.

    This has been my own practical experience. I have both Jennings and Irwin bits and have bought used sets from garage sales so this does work. I actually cut myself on one while I was working on one.

    I hope that this will help with those who are sharpening auger bits. Just be patient you will learn and you will have a new skill.

    Doug

    • I have done the same. My brother worked in a machine shop for some years, and is also interested in historical tool-making. He told me that in centuries past, people did amazing things with tiny files. That gave me the incentive to fix up the threads in question with a small file. It was horribly fussy work, and I wrecked a couple of old bits before I got the hang of it. Fortunately I practiced on bits whose spurs were gone anyway, so it didn’t matter. Replacement auger bits are not all that easy to come by these days, so maybe it’s not mere obsession with restoring things. (Or maybe it is.)

  18. Recently I was happy to find out that new Irwin twist bits for the traditional hand braces are available here in Canada through Amazon. I purchased a one inch one but was disappointed when it would only drill in about half an inch and then stop. At first, I couldn’t see anything wrong with it, the cutters seemed to be sharpened at the right angle. I had to compare it carefully with my old ones and finally noticed the inside of the spurs on the old ones were filed flat but the new one was sharpened with a bevel probably to speed up the production process. I filed it flat and sharpened it according to this video and it works great. Maybe this will help others.

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