Mortising JigComments (0)
Loose tenon joinery, like that used in the Easy Chair on page 50, is a great alternative to traditional mortiseand- tenon joinery. The latter requires cutting an integral tenon in one of the parts to fit in a mating mortise cut in the other part. But with loose tenon joinery, the tenon is a separate element that spans the joint to fit into a mortise cut in each part. Because this “loose” tenon is an easily machined strip of wood, making the joint tends to be more efficient than taking the traditional approach. However, loose tenon joinery typically requires the ability to cut mortises into the ends of workpieces as well as their edges. That’s where this jig comes in. Used in conjunction with a plunge router outfitted with an edge guide, you can efficiently and accurately cut perfectly matched mortises in both the ends and edges of workpieces. In use, toggle clamps secure the work to the jig, and the end stops control mortise length.
jig’s dimensions aren’t critical, so feel free to size it to suit your
particular work. What’s important is that the top’s rear edge is parallel to
the face, and that the face and top surfaces are square to each other. To ensure
this, ‑ first run the glued-up assembly facedown over your jointer to bring the
parts into one plane. Then run the jig upside down with the front face against
the jointer fence to square the top surface to the face. Finally, run the whole
jig upside down through your table saw to ensure that the rear edge of the top
is parallel to the jig’s face.
Illustration: John Hartman
Using the horizontal fence. Install the jig’s horizontal fence, with toggle clamps attached. After setting up for the first cut using a marked-out mortise, pencil mortise-extent lines across the top of the jig for setting up subsequent cuts. When routing, bear down with your left hand to prevent router tipping, and make sure to keep the edge guide in contact with the jig.
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