Foxtails and Keyed Tenons

The mortise and tenon joint takes endless forms to adapt to every situation. We just finished drawboring a mortise and tenon to lock it in place, but what if we couldn't or didn't want to peg it? If the tenon passes all the way through a piece, as it will in frames and sash, we could expand the tenon with wedges from the far end. If we expand the mortise a little bit on the outside, the wedged tenon will expand to fill it, forming a dovetail.

This works fine for a through tenon, but a blind tenon can also be expanded in similar fashion. A blind wedged tenon, or foxtail, goes into its undercut mortise fitted with wedges that expand the tenon as it bottoms out. Once it's driven in, there's no going back, and if a wedge is too deep or breaks, you're stuck with it. If the wedges expand the tenon enough to make it impossible to withdraw, but not enough to make it tight, you're also stuck. You might go so far as to make a cutaway test version of your foxtail tenon to test the joint. In any case, its a handy thing to show clients.

You can also blind wedge a peg. This is most handy in the odd instances when you need to lock a peg into end grain. In log building, this is how you peg in door casings. Saw a slot in the end of the peg and fit in a wedge. When the peg hits the bottom of the hole bored for it, it expands and locks the peg in place. Saw the peg off flush and drive in a wedge from the outside. Pegs check in, but they don't check out.

Keyed tenons are the extroverted opposite of the foxtail joint. In a keyed tenon, the mechanics of the joint are out for everyone to see. Where a foxtail tenon can never come apart, the keyed tenon is easily knocked loose for disassembly. A true tusk tenon is a haunched construction joint that pokes through a timber and bears a tapered key; but nowadays, any keyed tenon is called a tusk tenon. The key is truly more of a wedge and pulls the joint tighter as it is driven in. Fitting is easy if you make the wedge first and trace its taper onto the protruding tenon. Make the mortise for the key a bit further into the side toward the shoulder. This allows the key to pull up the joint as you drive it down.

Trim the end grain of the clamp joint with a low-angle shoulder plane.
Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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Responses

  • costanzo
    How to make foxtail tenon?
    5 years ago

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