The wedged loose tenon is really an
easy, strong and attractive joint. The advantage of making it loose
is that sometimes the component... a stretcher for example is large, and cannot be readily cut at the band saw, or table saw... sawing
by hand is a good option or this version where the tenon is loose.
The mortise can be made by drilling and
chiseling, slot mortiser, router, or other methods. The key aspect
of the joint is to make the mortises in all the pieces the same
width and the loose tenon should be the same width also... now the
length of the mortise is larger in the outside thin piece.
Why? It is just like when you fasten 2
boards with a screw....the screw slides easily through the first
piece and tightens in a pilot hole in the second....the head of the
screw locks it together.
This is exactly the same... the
edges act like the screw head and as they are tapped in they lock
the joint together.
Cut the tenon and make glue relief slots.
Drill holes at the wedge slots to keep it from splitting
unless you know the wood well... and the slots are cut
about 1/8" wide.
Glue should be on all surfaces... wedges, mortise, tenon,
piece mortise. Glue slots must run into the mortise so that when
the tenon is tapped in the glue can flow out. This will
allow the correct amount and eliminate the pumping effect of the
piston and cylinder... pushing the tenon back... and potentially
creating pressure in the joint... a few voids are welcome...
The spiraling cuts on dowels do the same thing since they are
continuous... cuts in the other direction weaken the tenon and
create a fault or weakened plane... not good!
The joint is finished in a couple of
ways which is only detail... leave it proud and bevel the edges with
a plane or cut and plane it flush with the surface...
This is really a simple joint and
because the long grain of the tenon is running long grain with the
mortise... it is a strong joint.
I like the wedges in a hard wood so the
fibers of the tenon and mortise compress... you can use a
contrasting color wood for detail. Just remember... just
because you know how to make a nice joint is not a reason to make
every joint a feature... don't overdo it! Pick a few important
joints in a piece for emphasis... don't make it look like a joint
making class attacked a piece of furniture. ;-)
Laguna Beach, CA
"All great work starts with love .... then it is no longer work"