I am building a Hundboard based on the design in Fine Woodworking’s Building Period Furniture. The sides are made of a glued up slab about 12″ wide which attaches to the legs with triple tenons ( 3 tenons about 2-3/4″ long with an inch between each).
I have two questions.
1. What is the purpose of using 3 smaller tenons rather than one large one? I’m guessing it has to do with wood movement but I can’t picture how.
2. What is the proper way of gluing this joint? I am inclined to only glue the top tenon and let the other two float, but this seems kind of weak.
Thanks,
Rich C
Replies
Rich, your thoughts are going in the right direction. Splitting the tenon has more than one purpose. First, if you excavate a long mortise-- 12" or so long, the cheeks are very long and they might want to bow away from the face of the tenon. Leaving plugs of wood between a series of mortices helps hold the cheeks together. Secondly, as you surmise, you glue only one of the tenon forks into one mortise.
Attached is a picture of a very deep rail mortised to a leg. The deep rail was needed for strength between the legs because of the weight and abuse the top would receive. Only the top fork was glued so that the top edge of the rail remains in line with the top of the leg. The bottom edge can float up and down as the seasons change, but the unglued tenon keeps the rail from twisting out of line if the rail should warp. Extrapolate what you see for your needs. Notice how the mortices are extended in the length a mm or so to allow the rail some seasonal wiggle room. Slainte.
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Sgian,
Thanks. It all makes sense now.
Rich
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