A bird's mouth and
wedge is a specialized batten.
It's used to secure a board on
its edge in a very quick way. Its claim to fame is speed of
setup. Depending on how it's used, or fixed to the
workbench, it may not even require setup.
Again, this is simply a scrap
or cutoff. It's a little longer and wider, or depending on
style, a little thicker, but it's still just scrap. This
particular bird's mouth starts out at about 20" long and a
bit over 8" wide.
Place your workpiece, tap the wedge, work!
What It Does...
It's a pretty simple device.
Take a look at the picture above... The cut-out for the
wedge is square on the left side and on the "bottom." The
right side is not. It is a compound angle, just like a
dovetail. It's angled on both the face and the edge.
With the wedge out of the way,
simply slide your workpiece against the left side. Let it
bottom out. Now, insert the wedge, give a gentle tap, and go
to work. It's that easy.
How to build it...
First, surface the board on
four sides (S4S). Cut about 4" off of one end. That will
leave you the other piece about 16" long. Lay out some
dovetails and join the two pieces together as you would any
other dovetailed corner. Then, clean up the joint... Next,
lay out the wedge.
The wedge doesn't go but about half way...
Anyway, when the layout is
complete, it should traverse about 3/4 of the face of the
board. In this case, it's about 6".
The wedge slope is about 10°.
The wedge on the face of the
board is about 10°. On the edge, the dovetail slope is about
1:8. I just grabbed a dovetail saddle to lay it out. With a
10° slope on the face and 6" depth, I laid out the wedge
with about a 4" base, and the top is about 3".
Finally, the square end begins
about 2" from the dovetailed side of the appliance. None of
these numbers are really critical, and all of this is just a
guideline set of values.