The work on the breadboard ends starts with cutting a 3/8” thick tongue on the top’s center section’s ends. That’s done with the stacked dado. The tongue is a half inch long so I used the two ¼” outer blades and a 1/16” chipper. This give me a little overlap so I can make the cut in two passes.
Cutting a matching 3/8” wide groove in the breadboard is next. The goal is to have a perfectly centered groove so the face of the breadboard and center panel are dead flush. To give me a little wiggle room the breadboard is two hundredths of an inch thicker than the center panel. If everything is perfect, I will have one hundredth of an inch to sand off each side. If not, that little bit should help me out when bringing the faces flush. It’s a lot easier to bring the breadboards down than the whole center panel.
The groove starts with the same 5/16” wide dado
stack. First the fence is set so the
dado blade is close to being centered on the breadboard. To get a perfectly centered groove two passes
are made rotating the breadboard end for end between them. The groove is measured and whatever amount
it’s too small is divided by two and the fence moved almost that much then
recut. From there I sneak up on a good fit a little at a time. Here is the setup and finished
groove. The magnetic featherboard helps
keep the breadboard tight to the fence and 90 degrees to the table.
One of the breadboards ended up with a perfect fit. Snug but not tight enough to require much
force to be set in place. The other end
had a little section that was too tight.
The chalk marks show the part of the tongue that’s too thick. That’s easily fixed with a couple passes
using the shoulder plane.
Here is the top with the breadboard ends dry fitted. They are long and will be cut down later but
they fit tight to the center panel with no gap at all. I did end up with a little variance at the
joint between the faces but in all cases it’s less than the one hundredth inch
I had allowed for so flushing them will be easy.
Cutting the slot for the spline is next. When I first laid it out per the drawings the
proportions did not look quite right so I cut some different lengths of paper
until it looked right. The top photo
shows what I selected and the bottom shows the resulting layout. The area highlighted in red is what gets
recessed 3/8” deep.
Preparation for routing the recessed slot begins with
clamping the breadboard ends on either side of the center section just to
provide a wider support base for the router.
The top photo shows this setup with the bottom a closer look at where
the slot is going to be routed.
The routing is done using a small trim router with a ¼”
diameter bit. This carbide bit is well
over 20 years old and is still sharp.
That’s because I regularly give the carbide cutting edge a quick honing
with a fine diamond stone before using it.
Here is the bit with the carbide tip cutting edge circled in red along
with the fine diamond hone I use. The
down side is that after all those years of honing the bit now cuts a slot just
a shade under ¼” wide.
These two photos show a closer view of how the bit is
positioned on the diamond hone for sharpening.
Note that the flat inside face is sharpened and not the beveled edge. 
The left photo shows the slot routing setup. On the back side of the router, you can see a
fence that controls the location of the cut and gives a straight edge. The right photo is a closer look at the
router with the fence in the background.
Since the slot is just over 3/8” wide multiple passes are needed. Also, the depth will be cut in three passes
of about 1/8” each so the bit does not get stressed and with my luck break.
Here the slot’s width is finalized and the first 1/8”
deep passes have been made. From here
it’s a matter of adjusting the router’s depth of cut by 1/8” making a couple of
passes then adding another 1/8” in depth to get to the full 3/8” slot’s depth.
This is what the full depth slot looks like. All that’s left to do is square up the back
end of the slot which is done using hand with chisels.
After the end is squared up the breadboard is put on and
the assembly is checked to make sure the just cut recess and the groove in the
breadboard line up. That’s one down and
three to go. The photo shows the
breadboard sticking out beyond the edge of the center section. That’s not an error it is supposed to be
long. The center section will change in
width when the humidity changes but the breadboard will not change in length so
while the size of the offset changes it will always be there and look like it’s
planned. If cut flush then part of the
time it would look fine but as the wood moves it would either be a little too
short or stick out just a little looking like an error.
Making the ebonized spline is next. They are made out of cherry and will be dyed
black later. The top drawing shows one
of the four in-place and the bottom drawing is of the spline itself.
The finished spline is only 3/8” wide and 3” long which
is a little small to work with. I start
with blanks about a foot long so they are easy and safe to work. Once ripped to width and thickness the 1/8”
deep offset is cut. There are several
ways to make the offset. The two I
narrowed it down to are using a router bit in the router table or the stack
dado set in the table saw. The router
table is picked because it gives me a better cut surface than the dado set
which means there is less sanding to achieve a smooth finish surface. This is what making the offset cut looks like
in progress. The routing needs to be
made in multiple passes otherwise there is a good chance of chipping during the
cut.
Next Up – Beveling & Dying Splines Plus Breadboard Attachment
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