Building a Dining Table, Part 2: Clamps and Pegs

The majority of my time on this project was spent surfacing the boards for the top.  I hand-planed all the boards from the rough-sawn stock, and I must have carried out four or five garbage bags of wood shavings in the course of this build.  (We should have enough kindling for our fire pit for the next few months, at least.)  I’m seriously considering buying an electric planer to help with the rough work.

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On each board, I began with my jack plane, going diagonal to the grain and taking a thick shaving , just to flatten the board and remove the saw marks.  Then I was able to decide which side would be the face and which one I could leave rough-planed.

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On the good face, I planed each board as straight as I could with my joiner plane and finished with the smoothing plane.  As it happened, I probably wasted my time with the smoothing plane because I still had to re-plane each board level after each glue-up.  Now I know.

As I finished planing each board, I edge-glued two or three together and let the glue set up as I continued planing the next boards.  The first glue-ups were pretty simple.

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Cauls and battens helped a lot with alignment.  I had no desire to thickness each board to the exact same thickness by hand, so they’re all a little different in thickness.  Only the top is leveled out.

As I began to glue panels to each other, things got more cumbersome.

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On the final two glue-ups, I ended up using my own weight to align the boards as they rested on cauls.  I used my pipe clamps to their fullest extent, and everything came together in the end.  The final dimensions of the top are 90″ long and 44″ wide.

In the meantime, as the glue dried, I worked on the leg assemblies.  Each I-shaped base is tenoned together with double tenons.  The tenons were big enough that they got cut with my ripsaw.

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I really need to sharpen it, but that’s a task for another day.  (As per spousal noise ordinances banning indoor metal work, all saw sharpening takes now place out of doors–and It’s way too hot outside for that.)

Cutting the tenons left a lot of small offcuts, which one of the kids thought looked a lot like building blocks.

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So this is what I found on my workbench the next morning.  I almost hated to clear it off in order to get back to work.  In retrospect, I should have challenged somebody to a game of Jenga first.

I always cut my tenons first, then use them to help me lay out the mortises.  I usually chop small mortises with a mortise chisel, but these mortises were big and deep.  So I drilled out most of the waste using a Forstner bit on the drill press, but then I squared them up by hand.

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I think this exemplifies my ideal power-tool/hand-tool balance.  I prefer to use the power tools to do the precision donkey-work, which is what they’re good at.  It saves me time and effort, which leaves me freer to do the fun tasks by hand.

Usually glue is more than adequate to keep a well-cut mortise and tenon joint together, but for extra security (and a cool, retro look) there are some ways to reinforce the joint by locking it together mechanically.  One time-honored method is draw-boring, or pegging.  At its simplest, it might involve assembling the joint, drilling through both members, and driving in a dowel to keep everything together.  But true draw-boring works a little differently (and please excuse the explanation if you already know this).

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First drill through the mortise only, then insert the tenon and mark the location of the hole on the tenon.  Pull the tenon out and drill through the tenon, offsetting the hole slightly toward the tenon shoulder.  The holes are thus intentionally misaligned.  The peg is shaved to an octagonal cross-section for a tight fit in the hole (the corners of the octagon dig into the round hole and hold the peg securely in place).  When the peg is driven through the misaligned holes, it pulls the joint together tightly.  There’s no need for clamps, and even glue might be optional.  (I did use glue anyway, for what it’s worth.)  Just drive the pins in and cut them off flush.  The joint is locked together forever.

I’ve used a number of different woods for draw-bore pins.  A tough wood like pecan works pretty well, but oak really does work best of anything I’ve tried.  It’s strong, flexible, and easy to shape with a chisel.  I perpetually keep a few pieces of straight-grained oak, well dried, for making pins.

The end pieces assembled, I then attached the trestle with tusked tenons in order to make the base dis-assemblable.  Full disclosure: I cut the mortises in the uprights before assembling everything.  Chopping mortises on something that’s already assembled would have been very awkward, so the picture below shows the whole base assembly dry-fitted.

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A tusked tenon is a tenon that extends well beyond the mortised piece and has a mortise cut into the tenon.  This smaller mortise has one angled wall that matches a long wedge, called a “tusk.” Normally you drive in the tusks to tighten up the joint, but we live in Alabama, where the Tusks-are-loose-a.  (Terrible, I know.  But I’ve been waiting years to use that joke.)

Before I put the table top on the base, I decided to stress-test it for strength.

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Yep, it holds all the kids.  It’s plenty strong enough to support the table top.

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2 Responses to Building a Dining Table, Part 2: Clamps and Pegs

  1. Sylvain says:

    You probably know this.
    If the distance between the tenon shoulder and the tusk mortise is shorter then the leg thickness, it will be possible to tighten the joint even if the leg shrinks.
    Will Meyers, building his Moravian bench:
    “When I mortised for the key I mortised about 3/16 in closer to the tenon shoulder. This is important, if you don’t the key will wedge against the mortise wall and not pull the leg up tight. […] It works like drawboring but uses a wedge instead of pegs.”

    • I do know that (thanks to Roy Underhill), so I under-cut the tusk’s mortise by about 1/8″. I didn’t happen to mention it in the post–one of the many little steps that get left out of a blog post like this.

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