3-Way miters in 3 steps

Synopsis: Designing a dining table without a lower stretcher for structural stability was a challenge Tim Coleman addressed using a 3-way miter. Commonly found in Chinese furniture, this joint is strong enough but relies on an intricate arrangement of necessary tenons, miters and tricky cuts. However, by building the apron as two layers, he simplified his work by using a thick layer with virtually square tenons and a thin top layer that was mitered. This he laminates two layers to give the look of mitered corners while maintaining the strength of the joint.

My furniture designs often rely on fittings in compact areas, so I want to maximize the strength of joints without compromising the integrity of small parts or cluttering a sophisticated design. I had to come up with a method.

I faced this challenge with my recent dining table commission. was intended to create The underside curve of the apron flows seamlessly from the legs to the floor, with no lower stretchers to disrupt these lines. We propose a 3-way miter at the leg-to-apron joint, a detail found in historic Chinese furniture. Did. Well made, it’s a strong joint, but it relies on an intricate arrangement of integral tenons and miters, requiring tricky cuts. Finally, I came up with a way to simplify the process of making it.

Cutting leg mortises and mitered indentations was not difficult. But I wanted the apron to be simple. So I decided to make them as two layers: a thick inner layer with a virtually solid tenon, and a thin outer layer that laminates inward after the tenon is cut.

Once the apron is laminated, cut the miter in thin layers to form the wings that will be glued into the leg mitered recesses. Cut a small miter into the tip.

With this arrangement, I got the best of both worlds: predictable strength and easy assembly of large 90° mortises and tenons, as well as the appearance of mitered corners. Additionally, mitered wings add an adhesive surface to reinforce the joint. A welcome boon given the lack of stretchers. Legs made in this way are design elements that improve strength and require finesse.

check the tool

Any project requires proper setup and alignment of machines and fixtures, but it’s worth highlighting the point here. With complex joints like this, the “slightly off” increases rapidly. The front-end work of checking tools and jigs eliminates a lot of back-end confusion and headaches.

The bevel builds up the legs

Thick legs are half the equation for strength and easy assembly of large square mortise and tenon joints on the table. However, I didn’t have solid stock thick enough to make these legs one piece, so as a workaround, the leg blanks he constructed in two pieces, one long end I mitered and glued along. As a result, the legs look and function like fat legs even though they are constructed with thin stock.

—Tim Coleman, longtime author of FWW, is a furniture manufacturer in Shelburne, Massachusetts.

Photo: Barry NM Dima.

Drawing: John Tetro.

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from fine woodwork #303

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