Wood Corner Joint Test: Which One is Strongest?

Professional woodworker Brad Holden shares his four favorite corner joints. Bonus: find out which one held up to our test the best!

Gluing dowels in joinery | Construction Pro Tips

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Traditional hand-cut joinery requires skill and a great deal of practice to master. But are those fancy joints necessary? Nah. I still use mortise-and-tenons or dovetails when a project calls for it. But for most projects, I just need joinery that’s strong and simple. My go-to methods include pocket screws, dowels, biscuits and the Beadlock system. There’s no reason to have all of them in your arsenal. Most serious woodworkers choose one or two, become proficient and use them for virtually all joinery. These four methods are strong enough for typical joinery, and they’re all affordable. — Brad Holden

 

Pocket screws in joinery | Construction Pro Tips

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Pocket Screws

You can get a basic pocket hole kit for about $30. You’ll need a supply of different lengths of special self-drilling washer-head screws (coarse threads for softwoods, fine threads for hardwoods). You likely already have a drill/driver, which is the only necessary tool. That’s a big plus—it saves you money as well as space in your shop. Once you’ve become a convert, you can pick up more clamps, accessories and jigs to really step up your production. The only downside to pocket screws is that without special clamps, they don’t automatically align parts during assembly.

Pros:

  • Fast
  • No large clamps required
  • Benchtop or portable

Cons:

  • Visible holes
  • Parts alignment is not automatic

Plus: Check out three amazing woodworking tools in this episode of Stuff We Love.

Drilling pockets with a jig | Construction Pro Tips

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Pocket screws / Drill the holes

Clamp your workpiece in the jig and drill the steeply angled holes. This unusual jig has two pairs of holes: one pair for thinner stock and one pair for thicker. It costs about $65 at harborfreight.com. The included drill bit bores a flat-bottom hole with a short pilot hole at the center to guide the screw into the adjoining part. A stop collar regulates the hole depth.

Driving the screws into the pockets | Construction Pro Tips

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Pocket screws / Drive the screws

Apply glue, clamp the parts into alignment and drive the screws. Some pocket hole jigs are portable; you can clamp them onto a workpiece that’s too large to put on your workbench.

Dowels used as joinery | Construction Pro Tips

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Dowels

A solid, easy-to-use doweling jig will set you back about $70. As with the pocket hole method, the only tool you’ll need is a drill. Then you’ll also need a supply of dowels. The dowels for joinery are different from the standard dowel rods found at hardware stores. Joinery dowels are grooved to keep glue from getting trapped in the bottom of the hole and preventing the parts from pulling together.
Unlike pocket screws, dowels align the parts and make both sides of the joint look the same (that is, no exposed screws). That’s good when both sides will be visible.

Pros:

  • Automatic alignment in both directions
  • Mating dowel holes can be positioned anywhere using dowel centers

Cons

  • Clamping required
  • Slow

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Drilling holes into wood using a dowel jig | Construction Pro Tips

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Dowels / Drill the holes

The Dowl-It jig I use is self-centering, with an integrated clamping mechanism. You can buy the latest version for about $50 online. Mark the hole locations on both parts, clamp the jig into place and drill the hole.

Applying glue to the dowels | Construction Pro Tips

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Dowels / Insert the dowels

Apply glue to the dowels and mating parts. Press the joint together and clamp. You can use shims with this jig to drill holes for offset parts. When necessary, use dowel centers to mark the starting points for drilling into the adjoining part.

Wooden biscuits used as joinery | Construction Pro Tips

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Biscuits

A plate (aka biscuit) joiner runs anywhere from $70 to $700. The $700 variety is really nice, but it’s not really necessary, especially for someone just getting into woodworking. A modestly priced model works just fine. A plate joiner cuts a semicircular slot in adjoining parts to accept a plate/biscuit, which is then glued into place. Biscuits come in different sizes to accommodate various part dimensions.

Pros

  • Fast
  • Easy to use
  • Easy to offset parts
  • Effective dust collection
  • Automatic alignment in one direction

Cons

  • Clamping required
  • Parts can slide during clamping

Cut the slots with a special biscuit saw | Construction Pro Tips

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Biscuits / Cut the slots

Mark joint centerlines on adjoining parts. Set the plate joiner to the desired cutting height, and set the cutting depth to match the biscuit size you’re using. Line up the guide mark on the joiner’s fence with your mark and plunge the cut. A DEWALT plate joiner costs about $170 at Amazon—buy one here.

Check out 20 marking hacks that are super useful for woodworking projects here.

Inserting the biscuits into the slot | Construction Pro Tips

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Biscuits / Insert the biscuits

Apply glue to the mating surfaces and in the slots. Insert the biscuit, press the joint together and clamp

Beadlock joinery system | Construction Pro Tips

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BeadLock

A Beadlock jig facilitates drilling mortises in adjoining parts, again using only a drill. This is one of many “loose tenon” systems. Instead of the tenon’s being cut from one of the adjoining parts, precut tenon stock is glued into a mortise in both parts. Beadlock mortises are just a series of overlapping holes, and the tenon stock looks like a stack of dowels. You can buy tenon stock, or you can buy router bits to make your own tenon stock. But you’ll need a router table for that, and it’s a bit fussy.

Pros

  • Easy to use
  • Automatic alignment in both directions
  • Extremely strong

Cons

  • Slow
  • Clamping required

Drilling down into a beadlock jig | Construction Pro Tips

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BeadLock / Drill the mortises

Mark the joint centerline on both parts, position the jig using its alignment guide and then clamp the jig into place. Drill the first set of holes, slide the drilling block to its second position and drill the second set of holes. Repeat the process on the mating part.

Insert the tenons into a mortise | Construction Pro Tips

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BeadLock / Insert the tenons

Apply glue to the mating parts and the Beadlock tenon. Press the joint together and clamp.

Testing the strength of joinery by increasing pressure on the joints | Construction Pro Tips

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Joint strength test

We made 24-in. x 24-in. L-joints from red oak for all four of these joinery methods. Then we applied increasing tension with a turnbuckle and measured the failure point with a scale. While admittedly not very scientific, the results were surprising. And it’s always fun to break things!

Wood split from failed pocket screw joinery | Construction Pro Tips

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Pocket screws

The pocket screw joint is the only one that didn’t break at the glue joint. The wood broke instead!

Failed joints from Dowels, Biscuits and Beadlock | Construction Pro Tips

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Dowels, biscuits, and Beadlock

While the Beadlock joint was the strongest, these three joints eventually failed the same way: The glue joint broke and the wood pulled free of its reinforcement.

Next, learn what you need to know about why wood moves here.

Breaing points of different kinds of joinery | Construction Pro Tips

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Strength is not the main consideration

All of these methods are plenty strong for typical woodworking uses. Unless the joint has to be especially strong, choose your method on the basis of speed or convenience rather than on strength.

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