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I
can't wait to get started in this week's work on this chest. Since I have added the mount
for the Incra Ultra on the Sommerfeld router table, I have brought it over to "center
stage."
I took 5 minutes to clean and paste wax the solid phenolic top. The blanket
chest sides will be very heavy — I want them to be able to slide with as little
resistance as possible.
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I cleaned and waxed all the
aluminum extrusions and used some dry spray Teflon lubricant on the runners of the
vertical fixture.
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I am spraying
more of that dry lubricant. I want everything to "glide"— even
with the heavy load of the long mahogany pieces.
Note, that I have screwed a pushpad to the vertical fixture. I have found
that one of the tricks to making great dovetails with this system, is to push this fixture
and the stock down on the table, rather than against the fence. If the 2 nylon adjustment
screws are set properly, they will keep the fixture against the fence.
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I take 4 long
boards on a "test drive." The cleaning and lubrication worked well. I can move
the heavy combination smoothly over the router — on to the next step.
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In the test run, I found
that the weight of the work wanted to find every little bump in the table. The standard
throat plate (lower left) was part of the problem. One blank plate came with
the router table. I used a 3/4" straight bit and made the zero clearance plate at the
right. This gave me an absolutely smooth ride.
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There are a number
of templates designed for this double dovetail cornerpost. It took only a minute or two to
find the one that would work best for the 3/4" stock I am using. I am using the IDDF
template and the CMT 5/8" 7o dovetail bit. This photo gives a pretty good
idea of how easy it is to use the template page to visualize the various parts.
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Part of the
beauty of the system is that all the template pages are full size. All you have to do is
place the board on the page. The instructions say that we want to have pins on the end on
each board, so I simply slide the board until I can see how the pins will work.
Note, that the board is slightly wider than it should be to have the outside
two pins centered. I am doing this purposely so that I will have extra width to trim away
when the sections are complete.
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Next, I
have to set bit height. The template page suggests a depth of cut (1/2"). I set this
measurement on the Incra depth gauge.
Note the item: "Spacing to set depth of cut: 1-1/8" That is a part
of the Incra setup. I will use that in a minute.
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I
adjust the router bit height to that depth.
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Then, I make two cuts on
two boards to test the router bit height. Remember the "Spacing to set depth of cut:
1-1/8"? This is where it is used. The first cut is with the bit half-exposed. That is
the "0" point. Then, the fence is moved to 1 1/8", and a second cut is
made.
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This is the result of that cut. The two boards fit together and are a little loose.
A slight adjustment to the router bit height will tighten that fit. I do not want it to be
too tight — there has to be room for the glue.
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The next step is to center
the fence to the workpiece. I am using a piece of scrap that is exactly the same width as
all the boards (6"). I have measured and marked the middle point. I align that mark
with the centerpoint of the router bit and bring the fence up and lock it in place.
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I now route this piece in one direction, turn it around and route it the reverse
direction.
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With the
router stopped, I place the piece that I just routed and align the bit with the groove.
Once it is visually centered, I move the fence to the block. In this example, my first cut
was right on. The fence is at the centering point.
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With the fence locked at
the centerpoint, I move the template to the mark that the book recommends as the centering
mark.
I am ready to cut the "A" positions on all the boards.
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I lock the vertical fixture
in place. The middle screw is the locking screw. I have adjusted the other two screws to
get a smooth travel with little side-to-side movement.
I have cut a piece of MDF the same width as the other boards. I place this
against the vertical fixture. It will serve as a backer board to minimize tearout.
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I am making my first cuts.
I am cutting four boards and the MDF backer board at a time. I am using two clamps to hold
them securely on the vertical fixture.
Here is a hint for good cuts with the Incra Jig: when you push work along the
fence, use your force to push the vertical fixture straight down and forward through the
router and let the fixture guide against the fence. My right hand is firmly pushing the
pushpad I installed. My left hand is just assuring that I keep the fixture flat on the
table.
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This picture was taken
after the last of the "A" cuts was made. The dovetail sockets are wider than the
dovetail bit. This was done by following the template. It detailed two cuts for each of
the sockets — giving the wider cuts. This extra room is for the double dovetail
insert.
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Let me tell you, that is a
lot of exacting dovetail routing - 16 boards, 32 ends, 320 cuts. But, it went smoothly,
and no errors were made. I am ready to go to the next step.
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