Wedged Mortise & Tenon
This joint will never loosen!
By Tom Caspar
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Tap, tap, tap. The wedges go home, the glue squeezes out and a big smile lights up your face. “This joint isn’t coming apart for a hundred years,” you say. “It’s as solid as a rock!”
Making a wedged mortise-and-tenon joint is richly rewarding. Once you understand how it works (see photo, below), you can’t help but admire the joint’s elegant simplicity. It also sends a message. A wedged joint says to one and all, “This was made by a skilled woodworker.”
How the Joint Works
Here’s a cutaway view of a wedged mortise-and-tenon
joint. Driving in the wedges forces the tenon to flare into
a fan or dovetail shape. The mortise is tapered to match
the angle of each wedge. Like a dovetail, this joint can’t
pull apart after the wedges go home.
This tenon has two unusual features: saw kerfs that create
flexible strips and holes that disperse the strain that the
wedges create. The wedges cause the strips to bend; the
holes prevent the bend from splitting the rail.
This story originally appeared in American Woodworker July 2006, issue #122.
July 2006, issue #122
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