RWW 170 Center Bits

An entire episode dedicated to a specific type of drill bit. Only a woodworker could be captivated by something like this!
Not often talked about and not commercially available from modern manufacturers the center bit gets forgotten about. These are easily my favorite bits for hand tool woodworking and my modern brad points could learn a thing or two from them as well. Here I will discuss the merits of the center bit and how to sharpen them.

11 Responses to “RWW 170 Center Bits”

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  1. Great comprehensive look at center bits! Definitely a personal favorite and a greatly under rated bit.

    One important thing I would like to add to what you covered here for anyone looking to add a few of these to their kit is to watch that the guide point is centered. It is common to find these bits where a previous owner has sharpened the center point unevenly and basically moved it off of the center of the bit. When this happens, the spur will score a hole either larger or smaller than the cutting edge will cut. When this happens, the bit either bores a very rough hole (when the scoring spur scores narrower than the cutting edge) or the cutting edge doesn’t clean out the entirety of waste from inside the scored circle and can even split out a chip. I’ve had to correct far too many of these bits for this problem because someone filed the center point a bit too heavily on one side.

    So to fix this problem, I would suggest trying to lightly bore a test hole after dressing the spur but before sharpening the cutting edge. It will become apparent very quickly if the point is not centered. If you find that it isn’t centered, you will need to correct the centering of the point first by filing the side that it is offset toward. Do this carefully and keep testing so you don’t go too far. Stop filing that side of the cutting edge when the diameter cut by the scoring spur and the cutting edge are the same and the hole comes out perfectly clean. If it is ragged at all around the perimeter then there’s still work to do to center the point.

    • Shannon says:

      Good tip Bob, they are called center bits so having an off center point is just silly. Somehow in my 30 minutes of video I didn’t cover that point. I agree completely though I have to admit I have been very lucky with my bits and only had to correct the point a few times.

  2. Bob Easton says:

    Good lesson Shannon!
    For those who haven’t seen these bits in action, you’ve opened our eyes.

    Of course, now that you have yours, you can do something like this that drives up the price of center bits. :)

  3. Kenji horvath says:

    I just saw an episode of pawn stars where a set of vintage spoon bits and a drill came in. Go for it!! I think it went for a few hundred :)

  4. Jason says:

    Great video! There was a boring article (pun intended) in Popular Woodworking a few months ago about 18c bits. These center bits were some that were discussed as well as some other more obscure styles, it was an interesting article.

    On a second note, you need to do a post or video on that FANTASTIC awl. Did you make it or was it made by a blacksmith/toolmaker. I need to know more! :P

    • Shannon says:

      Yes I remember that article. It is funny what some of us consider everyday and others consider obscure too. I have to remember what a blessing it is to be involved with a museum and get to play with all these old tools all the time.

      The awl is actually a prototype of a tool that Shenandoah Toolworks is working on. No ETA on production yet, but I understand Norm and Jeff are homing in on a release date in the next few months. When I know more I will certainly talk about it. It is a fine tool.

  5. Eric Rusch Sr says:

    Great video Shanon.
    Those are worthy of tool chest space for sure.
    Thanks.

  6. Nate says:

    That’s a great video. Its too bad these aren’t commercially available. I’m going to have to keep an eye out for a set of these I would really like to try them out.

  7. Michael says:

    Those look just like a cross section of forstner bits. Both style of bits work on the same principle. Score the outline of the hole and scoop out the waste. The only real difference is the power driving them.

    • Shannon says:

      Perhaps and there are good and bad Forstner bits so the good ones may come close. The geometry of the cutting lip is key to create that slicing cut and the pyramidal shape of the point also is a big part of the equation for these bits. I don’t see a modern amalgam of the center bit and that is mostly because high rpm power drills have eliminated the need for subtlety and geometry that reduces the work load.

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