I was making an end table with
triple miter joints and could not see how I would be
able to get the joints fitted perfectly without a miter jack to
help me plane them at exactly 45 degrees.
Tony Seo posted
a link to an online auction which showed a
type of miter jack
which was new to me. It looked intriguing and less
complicated to make than the traditional open design. I
decided it would be nice to have one of these to help make these
joints. The one I am making in this description is
actually the second one I have made; I did not document the
I had some left over
8/4 and 4/4 hard maple that I thought would be good for this. I wanted the miter jack to be wide enough to take stock that was
at least 3" in each dimension. I glued up two pieces of
8/4 hard maple, so I would have 3 1/2" thickness, and planed it
to square it up. It is important that each edge be made as close
as possible to 90 degrees. This piece of wood is about 3
1/2" by 3 1/2" by 9 inches long.
Here are all the parts used to make the miter
jack after dimensioning.
The main center block is the big rectangular
prism, the sides are the two 4/4 boards behind. The sides should
be exactly the same height as the center block and about 6
inches longer. The rails are the two 1/4"x 5/8" strips. Four rails, each the length of
the center block, are needed.
The screw will be made from the
1x1 piece of maple in the foreground. One piece, the end block,
is not shown. Another miter jack is just on the left edge of the
picture. This miter jack is too small to use for the current
project, being only big enough for 2" stock, so I am making a
Using a Stanley 45 to plow grooves in the sides
of the miter jack for the rails. The central block will also
have grooves. The rails are glued into grooves in the central
block and slide in the grooves on the sides.
Take very special
care to make sure that the grooves are parallel to the sides and
don't veer off at the end of the board. If they aren't really
straight, you may need to use a Stanley #79 or equivalent to
straighten them up (DAMHIKT!).
Here the rails are being glued into the grooves
that were plowed in the center block of the miter jack. The
sides are in the foreground with the grooves shown. It is worth
taking extra care to make sure that the grooves are *really*
parallel to the edges. Even so, the rails might require some
trimming to get a good fit between them and the sides.