• Sunday, February 10th, 2013


Lee Valley Tools recently made available Square Hole Punches that easily form a square hole for filling with a square peg.

A simple peg or, even better, the drawbore method, are time-tested ways to reinforce mortise and tenon joints. I prefer the look of a square peg, but it is much easier to use a round peg inside the joint. I have tried various methods such as whittling the lower portion of a square peg into a roundish shape. Still, it is fairly tedious to neatly form the square portion of the hole with standard tools.

I have tried using a corner chisel and experimented using a hollow chisel mortising bit for this. Despite some success, I was still not happy with those methods. Lee Valley has made this much easier with their Square Hole Punches. Please see their website for how they work. I’ve tried them out in the shop and they work well.

They are well made and cleverly designed – except for one problem! However, I think this problem could be solved by adding some options to another one of their new tools, the Dowel Former. I sent the following message to Lee Valley. I invite your comments.

Hi Lee Valley folks,

I would like to suggest a coordination between your excellent Square Hole Punches and your new Dowel Former.

As you know, the diameter of the round hole in each Square Hole Punch is 3/64″ less than the size of the punch. I think I understand why. If the hole were larger, the thickness and strength of the wall of the punch would be compromised. If it were smaller, it would be too hard to drive the punch. Because the punches are sized in common convenient measurements, such as ¼” and 5/16″, the holes are necessarily odd sizes in the 64ths, such as 13/64″ and 17/64″, respectively.

However, when using the punches, I would like to use the drilled hole to insert a round peg for the mortise and tenon joint, and then fill the square hole with a square plug. I think for many woodworkers that would be the major benefit of the Square Hole Punches. However, to my knowledge, dowels are not available in odd sizes such as 13/64″, 17/64″, etc. Machining my own dowels is a hassle I would rather avoid. Whittling them to those sizes is tedious and inaccurate. True, I can make my own dowel plate but it is not likely to be as good as what you can manufacture, and I like working wood more than metal.

One solution would be to make the Square Hole Punches a bit larger, so that the holes would be in 32nds. For example, the ¼” punch could be 17/64″ and its hole would then be 7/32″. But, once again, who has a 7/32″ dowel? Not a good solution. Another approach would be to make the punches in sizes such as ¼” + 3/64″ = 19/64″ and  5/16″ + 3/64″ = 23/64″ so the round holes will be handy diameters, namely ¼” and 5/16″, respectively.

Enlarging the round hole is not a good solution. It would likely create inaccuracies and sloppiness, especially since enlarging it up to the next common dimension would make its diameter equal to the width of the square hole.

I think there is an easier approach. I suggest keep the Square Hole Punches just as they beautifully are, and make inserts available for your new Dowel Former to form dowels which fit the holes in each of your Square Hole Punches. I suspect this could be done relatively easily without a lot of retooling (unlike altering the sizes of the punches), and, if I understand correctly, you manufacture the Dowel Plate at your facility since it is a Veritas tool.

I present this suggestion in the context of having the highest regard for your company and the contributions you have made to the craft of woodworking. I plan to post this suggestion on my blog at and invite comments, as readers so often come up with good ideas and constructive suggestions.

Thank you very much,

Rob Porcaro

Category: Tools and Shop
You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

6 Responses

  1. hi rob,

    the inserts veritas uses in their dowel former look very similar to drill bushings (if you don’t know what those are, try a search for that term at you can buy drill bushings in nearly any size. they are made of hardened steel.

    it looks like the rim of the drill bushings is rounded over, whereas you would want it sharp for making dowels. it seems like it would be an easy fix to just grind the top of the drill bushing down a bit until the rim is sharp.

  2. 2

    Excellent idea, Rob.

    I’ve found that, more than any other company I know of, Lee Valley tends to be the most responsive to my abundant suggestions.

    And unfortunately the only one I’ve not really received a favorable response to was the suggestion to bring back the old countersink.

  3. 3

    Instead of drilling 3/64ths less than the punch, how about 4/64ths? Then you’ve got an exact match for the next smaller dowel size, and only 1/128th slop (each way) in positioning the punch. It seems like if you always pushed the slop in the same direction, you’d get good alignment for a series of plugs. (OK. You might. I don’t really know. Which is why I’m writing this. I’m wondering what you think.)

    In other words, it doesn’t really matter if the dowel and the square plug are concentric.

    This works for all punch sizes but one, because there’s currently no 7/16th dowel cutter to ‘match’ the 1/2 inch punch.

  4. 4

    Thanks, Ethan. We’ll see.

    Yea, Dave, sounds like a good workaround. Thanks. Still, I’m hoping Lee Valley will close the loop on this so workarounds are not needed. If not, I’m going to keep your idea in mind.


  5. Rob,
    I just completed a piece with 90+ decorative square pegs inserted with the LV square hole punch. I actually found it more accurate to use a square (as they suggest) to orient the punch, and then sight through the punch to the pre-drilled hole. That eliminated the play from the undersized drill bit and ensured that the hole was dead center. That being said, the whole method-of work was not ideal, and I’m not anxious to repeat the process.

  6. 6


    Yea, it would be good to not have do workarounds. Maybe Lee Valley will step up on this one because it just makes sense, and I’m guessing it would not involve major tooling changes to produce the proper size cutters for their new dowel former.

    Thanks for your comment.