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by
Dave Boulton
photos by Donna Griffith
illustration by Len Churchill |
MISSION COFFEE TABLE (part 2) |
When your
panels are dry, plane them down to 1/4" thick. Next, joint
one edge of each panel. This will be your reference edge. Now
is the time to trim the panels to final width and length with
a tablesaw. The measurements found in the materials list will
create a perfect fit. However, due to seasonal movement of the
wood, you’ll want to remove a further 1/16" off each
edge. This frame-and-panel design enables the panels to
float inside the frames without fasteners. By removing the extra
amount, the wood in the panels can expand and contract with
changes in humidity—a key strategy for preventing panel
cracks.
Joint and trim all back rails, back stiles and the kickplate
to final length and width. Use a 1/4"-wide dado blade in
your tablesaw to cut 3/8"-deep panel grooves in the rails
and stiles. The stiles require a groove on both sides. Here’s
a tip: if you make a pass from each side that adds up to 1/4"
in total, all the grooves will be perfectly centred. Complete
grooving operations on all back rails and stiles at the same
time with the same machine set-up. This ensures consistency,
which is key to a flawless assembly later.
 |
| Bookmatched
grain laminations are dramatic and true to Mission
tradition. This sawing technique was used to create
each of the three back panels. |
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In addition to supporting the coffee table, the legs act as
stiles with grooves, supporting the side rail tenons. The only
thing is, these grooves mustn’t extend the entire length
of the leg. That’s why you need to use a table-mounted
router to cut them, not a dado blade.
You’ll find that a 1/4"-diameter spiral bit does
the nicest job here. Set up a fence with a clamped stop block
to limit leg groove length.
Before you start routing your legs, mark which one goes where.
The grooving operation creates left- and right-hand legs, so
be careful. Take several passes for each groove until you get
to the full 3/8" depth. White oak is dense wood and you
don’t want to overload your equipment.
Mortise-and-Tenon Joints
You have several tenons to cut, and there’s more than
one way to make them. My favourite approach uses a dado blade
in a tablesaw. Adjust the blade to the correct height for the
sides of the stiles (the cheeks), then bring your fence into
position with a short stop block clamped to the fence. Locate
the block so the end of your workpiece moves past it as the
mitre gauge slides forward. The stop regulates the location
of the tenon cuts, but the wood must slide past it before contacting
the blade. This procedure minimizes the risk of blade binding
and kickback. Cut a tenon on a piece of scrap to confirm that
you have the blade set to the right height.
Your goal is 1/4"-thick tenons that are 1” long.
Once you’ve cut the sides of all rails and the kickplate,
raise the blade up to 3/8" above the table and cut the
bottom shoulders on all of them. Do the same thing on the top
shoulders of the lower rails and kickplates, but leave the tops
of the top rails alone for now.
The top rails feature what are called haunched tenons. Haunching
extends the full width of the tenon for the first part of the
tenon, with a more typical, narrower profile further along.
This feature takes more time to build, but it creates extra
strength where the mortise nears the top end of the leg. Mark
your tenon 3/8" in from the shoulder and 3/8" down
from the top. Cut off this waste with a fine-tooth handsaw.
Reset your tablesaw to cut the tenons on the back stiles. Although
they’re 1/4" thick like all the others, they’re
only 3/8" long to allow them to sit in the rail grooves
alongside the panels.
Next, mark your mortise locations, and cut them according to
the size of the mating tenon. The mortises all sit in the panel
grooves you cut previously in the legs. All you need to do is
deepen the grooves in the correct locations. The plans show
more details. The kickplate calls for mortises too.
Grab some of the extra leg stock you milled to use as a test
piece for your machine set-up. I removed as much waste as possible
within the mortises using a 1/4"-diameter Forstner bit
in a drillpress, followed by some chisel work to clean up the
holes and square up the ends. Aim for mortises that are 1/16"
deeper than your tenon length, providing room for excess glue
during assembly.
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1. Develop a plan |
2. Frames and panels
3. Finishing up |
4. Drawer construction |
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