JOINT MAKING OPERATIONS
DOU B LE-DOU B LE BOX JOI NTS
As in making conventional box joints, the diameter of the router bit used is
the most important factor in making good box joints. Before attempting a
double-double joint, you should get some practice making the conventional
box joint.
Templates for Double-Double Box Joints have six series of cuts. Full length
Red and full length dashed BLACK lines are for the pin and tail workpieces.
There are two different series of short lines for each of the middle sections.
To avoid confusion and mistakes, carefully refer to the full-sized plan for the
selected template before making each series of cuts.
For best appearances of this joint, the depth of cut should be exactly the
same as the bit diameter. As in the previous section on Double Dovetails,
the center sections may be made by one of two methods; vertical cuts only,
or the method which also requires sliding cuts. Again, the difference
between the two methods will be in finished appearance only due to direction
of wood grain.
With either method, the middle pieces become extensions of
both tail and pin workpieces which add to their length when assembled. The
approximate wall thickness dimension is listed on the template plan page.
Template
Number
Description
3/8" Double-Double Box Joint
30
38
Plan
Page
1/2" Double-Double Box Joint
31
39
1. Select Stock Width
The decorative nature of the Double-Double Box Joint requires that certain stock widths be
used in order to produce a finished joint that is both visually pleasing and structurally sound.
On the full-size plan for each template pattern, there is a chart to help you select your stock
width and its corresponding symmetry mark. The selection of a stock width from this chart
then determines which series of cut lines will be used for the pin, tail and the two middle
section cuts. For example, if a lower symmetry mark is called for from your selected stock
width, any lower yellow diamond on template is a symmetry mark for alignment to cursor.
If
an upper symmetry mark is called for, any upper yellow diamond on template can be used.
2. Set Depth of Cut
Set the depth of cut equal to the stock thickness which should also be the same as your
router bit diameter. DO NOT set the depth slightly greater than your stock thickness as you
do for conventional box joints.
3. Center Board for Symmetry
Use the CLINCHER
Rabbit and the TRU-CENTER scale to center the bit on your workpiece
following the instructions in the earlier Section on
Making The Perfect Joint. After finding
center, lock carriage and install the selected template. Take one of your workpieces and
place a small pencil mark at its center on one end. You can do this by placing it against the
fence and up close to the bit.
4. Align Template
With Carriage locked and
Rabbit still aligned to cursor, adjust the template in its slot until
one of the
symmetry marks (upper or lower as pre-determined in step 1 from the template’s
Symmetry Chart) is in alignment with the cursor hairline. Be sure that there will be enough
cut lines to the left and right of cursor to make all the cuts over your board width. You can
quickly verify this by making a comparison of the center mark on your board to the template
and its position under cursor.
5. Making the Pins and Tails
(Remember to include the middle-section wall thickness in length of boards)
Clamp your pin boards to the VPF with a backing board as shown. The backing board will
prevent splintering as the bit exits the cut. Install a stop block on fence to limit the travel of
the VPF to prevent damage to the fixture. Make the series of pin cuts. Flip the boards end
for end and repeat the same cuts. Now clamp the tail boards with a backing board to the
VPF and make its series of cuts on both ends. Note: The first cut on the tail board will be
an open cut meaning that you will be cutting away the edge of the board adjacent to the
fence. To prevent this first cut from splintering, make the cut in several small side by side
passes.
Router Table Top
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