With all the mortises made it’s time to work on cutting
the tenons that go in them. The first
pieces will be the front and back stretchers shown in the photo below.
Since the pieces were a little long, they are cut to
length in the chop saw using a stop block.
That’s followed by laying out the tenon.
Because this tenon is not centered side to side along with the regular
layout marks I have added the depth of cut for each face. Below the top piece has had the first face
cut making two passes using the stacked dado. 
My stacked dado set has two 1/8” outer blades, four 1/8”
chippers, one 3/32” chipper one 1/16” chipper and 10 shims ranging from .004”
to .02” thick. Using them in combination
I can cut dados ranging in width from ¼” on up.
This setup uses two 1/8” outer blades and two 1/8” chippers which gives
a ½” total cut width per pass. I could
have added more chippers to get to the exact width but then I would have had to
add a sacrificial piece to the rip fence so I wouldn’t cut the fence
itself. It’s just easier to stack pieces
up a bit over half the total and make two passes. Additionally, a narrower cut puts less strain
on the saw and decreases the total rotating mass which reduces the time it
takes the blade stack to spin down and stop.
Here is what the selected parts look like.
For this tenon the second and third cuts will both be ¼”
deep so the dado set will be raised and the cuts made. With these cuts the three sides of the tenon
will be done with just the thickness to do.
The last cut establishes the thickness of the tenon which is the most
critical and that’s because it needs to be a snug fit. Too tight and it could cause the leg to
split, too loose and the glue joint will be weak. The height of the tenon is not as critical so
it gets cut first allowing me to test the width to get it just right. Here is what the finished tenon looks like.
Cutting the double front to back stretchers is next. 
The layout follows the same process as before with one
addition. The top and bottom stretchers
are the same size but have a different orientation. By that I mean the top stretcher is wider
than tall and the bottom stretcher is taller than it is wide. Because they are both 7/8” by 1” it makes it
really, really easy to get them mixed up and make an incorrect cut. To help keep that from happening a 1 through 4 numbered
cut sequence is added. I also have
a couple of cutoffs for test pieces. The
actual cutting follows the same procedure as the front/back stretchers. I just need to be extra careful making the
cuts.
Here is what the two sets of stretchers look like when
done set in the orientation they will be installed.
Now with all the tenons cut I can do a test fit. In doing so I found that about half of them
were just a hair too tight. That’s solved
by taking a couple of passes on the tenon face using a piece of 120 grit
sandpaper attached to a flat surface.
Here is what the friction fit assembled seat looks like.
Routing a radius on all but one of the exposed edges is
next. There are two and maybe three
different sized radius router bits to be used.
First is a 1/8” shown below being used at the bottom of the legs. The piece of plywood behind the leg with the
handle is a backer board whose purpose is twofold. First, is to keep the leg square with the
fence and second to act as a backup to reduce chipping when the bit exits the
end grain cut. This bit also gets used
on one edge of the legs and the tops of the six horizontal stretchers. Because it is so small the radius can be cut
in a single pass.
Next is a 3/8” radius for the top of the leg and most of
its remaining edges plus the bottom edges of the stretchers. The setup is similar to the previous 1/8” bit
except that instead of being cut in a single pass I will make three
passes. That’s done to reduce the load
on the router and reduce chipout. While
going from a 1/8” bit to a 3/8” bit doesn’t sound like all that much. However, when you do the math the total cross-sectional
area removed is 9 times as much. Here is
what that looks like ready to make the last pass on the edge of the legs.
With all the routing done the flat faces and most of the
edge routing can be sanded using a ¼ sheet pad sander. However, there is still some hand work to do
on the top and bottom of the legs. Here
is a before and after of the top of the leg corner blending where all of the
edges were routed with the 3/8” bit.
The other two top leg corners are a little different in
that one vertical edge has a 1/8” roundover and the one facing the camera has a
hard 90-degree edge. The top photo is
before the blending and the bottom one after.
The bottom of the legs also need help in blending all the
routed edged together. The left leg is
the before and the right is the after.
Most of the blending is done with the fine end (right) of this half-round 4-in-Hand rasp.
The final blending is done by hand using 220 grit sandpaper until it
flows and feels smooth with no hard edges.
The stretchers are treated a little different in that
they are not sanded at all. The flat
faces are left with the 80-grit surface right out of the thickness sander plus
the routed radiuses are not sanded either.
The reason for this is when the seat cording is wrapped around them it
needs the wood surface to have some tooth to in order grab onto. With that in mind here is an end view of the
stretchers.
Next Up – Assembly & Finishing & Seat Weave Layout
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