The jig for cutting the box joints sets on the table saw
as shown in the photos below. The top is
from the user’s standpoint behind the saw and the bottom photo is from the
front that shows the two different pieces of the wastebasket.
Picking material is next.
Baltic Birch would have been my first choice but it is no longer
available in the area where I live.
Because the quality of regular plywood is not consistent enough for this
project, I decided to go through by stack of leftover furniture grade veneered
plywood and came up with these pieces of oak and mahogany. There is also one piece of vinyl skinned MDF. It may be used for the sliding part of the
jig to reduce friction and because screwing into or gluing of the piece is not
required. There is also a small scrap
of quarter sawn red oak that is for the runners.
The runners will sit in the two miter slots in the top of
the table saw and will guide the jig while it’s being used. The red arrows in the top drawing point
toward the two runners. The fit of the
runners in the miter slot is critical to the overall performance of the
jig. They need to just fit in the slot
with no noticeable play but without binding.
There is not much tolerance in the fit.
Quarter sawn red oak was chosen for its stability and because it’s a
hardwood. The blank started out at about
.775” and the miter slot is a nominally ¾”.
Since the oak blank is only about .025” oversize the thickness sander is
used to gradually thin the blank down to fit.
In a perfect world the table saw slots would be exactly ¾” with
perfectly parallel sides. Unfortunately,
that’s not the case. As I got close the
blank would fit in some places and bind in others. In the past when fitting the steel guide on
the saws miter fence I ran into the same problem and ended up using a file to
smooth out the sides of the slot as there were scallops from the original
milling of the slots. Apparently, the
work I did while enough to make the fence run smooth it wasn’t enough for these
runners. After locating the high spots
and about 15 minutes of work with the file the oak blank ran smooth without any
play. However, the slots are not the
same size as one is .753” wide while the other is .757”. Not a lot, but enough that the narrow runner
would show obvious play when put in the other slot. Anyway, the bottom photo shows the oak blank
fitted to the wider slot.
The slot is a little over 3/8” deep and the blank needs
to be a little less than that for clearance.
Here is the saw setup for ripping the runners. After the second runner is ripped it gets
thinned down to fit in the narrower slot.
Also shown is the yellow safety push block I use to keep my fingers away
from the blade. 
With both pieces fitted to the slots width they run
through the thickness sander is used to remove any saw marks and get to the desired
clearance. Here the gap shows the
difference between the runner thickness and the depth of the slot in the table
saw. With that done they are set aside
to make sure they don’t warp, twist or otherwise move around.
Next is to take the mahogany veneered piece of plywood
and start work on the jig’s base which is shown in the top drawing. Before that I need to change the blade on the
table saw. The blade now on the saw is
for ripping or crosscutting solid lumber not plywood. If it’s used to cut plywood the cut edge is
terrible, rough with the finish veneer all chipped along the cut. The bottom photo has the current blade on the
left and the plywood blade on the right.
Besides the difference in tooth count the geometry of the grind of the
carbide tips between the two is drastically different.
First is to get a straight edge to work from since the
existing piece’s edge was cut freehand.
You can see the gaps under the level in the top photo. To get it ready to straighten I had to knock
the high point down in the center using my hand plane so the panel would not rock when it was set
up against the 8’ level and run through the table saw. Once the first edge is straight the piece
gets flipped and that straight edge used to cut the original edge true. The completed cut is shown in the bottom
photo.
Cutting a clean square edge is done with my sled on the
table saw. Here the first edge is trued
up which is followed up by flipping the piece and cutting the other end giving
me a blank with straight parallel edges and 90-degree corners.
The short edges get checked and the worst one gets cut
off when the panel is cut to length.
Last is to cut the base to width and then use the offcut to make the
Fixed Back.
Cutting the dado in the base where the Fixed Backer will
go comes next. This starts by swapping
out the plywood cutting blade with my stacked dado. The reason for this change is because I want
the bottom of the cut to be flat. Here
the cut on the left was made with the dado blade while the cut on the right is what the
plywood blade makes.
In the top photo you can see the two 1/8” wide dado
blades I used to make roughly a third of the cut. If I wanted to make a wider cut with each pass I would have
added chippers between these two.
The bottom photo shows the base where the white piece on the right is
the table saw fence. The dado gets made
in multiple passes starting at the right then the fence gets moved to the right
which makes the dado blades cut the dado wider on the left side until the dado
just fits the Fixed Backer.
Next Up – Fixed Backer, Sides & Table Saw Guides
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