994 4
Good Reason to Go Backward
Hogging off a lot of solid wood is an invitation to chipping or
tearing out the solid wood, particularly on the curves. Clamp
the patterns and the parts securely to your bench and make
the fi rst pass moving the router counterclockwise around the
outside of the pattern. Climb cutting in this way helps to reduce
chipping and tear-out. Drill two holes at the mortise locations to
allow the bearing on the bit to reach the pattern below.
After routing the mortises, the corners have to be squared. I
use a chisel and put the back against the end-grain edge of the
straight part of the mortise. Holding the chisel fl ush, swing the
corner down to establish a straight line.
Turn the chisel 90 ̊ to set the perpendicular line at the end of
the mortise. Then, go back to the end-grain side and force the
chisel down as far as possible, cutting across the grain. After
cutting the two opposite end-grain faces, make paring cuts
with the grain.
The tenons will fi t in the width of the mortise – or at least be
very close – from the template. To get them to fi t in thickness,
and to establish a shoulder on the inside of the joint, trim half
the difference in thickness off each cheek of the tenon, using
the jig shown in the photo above right.
Before fi tting the tenons, chamfer the ends. This makes
starting the tenons in the mortises easier, and it prevents the
tenon from doing any damage on the way out of the other side
of the mortise. Start the ends in the mortises and push down.
If they stop, look to see which face of the tenon should be
trimmed.
Tight But Not Too Tight
Aim for a snug fi t. It’s right when you can force the fi rst part
of the tenon into the mortise by hand, and are able to lift both
pieces without the joint coming apart. Take a few licks with a
card scraper or rasp to remove the saw and router marks from
the tenon.
This loosens the joint just enough to get it almost all the
way home with hand pressure. A few taps with a dead-blow
mallet seats the shoulder of the joint. Mark a pencil line where
the cheek of the tenon meets the face of the end piece. After
all the work of putting the joint together, it’s time to take it
apart again to make the small mortises for the tusks.
The tusks pull the tenon into the mortise by bearing on the
face of the mortised end. Locating the back of the mortise just
behind the face ensures this. After offsetting the pencil line
on the tenon^1 ⁄ 16 " back, mark out a square, centered mortise
and cut it with one stroke of a^1 ⁄ 2 " chisel on the hollow-chisel
mortiser. A block of scrap under the tenon holds it above the
machine’s table and prevents the back side from tearing out
as the chisel exits. This mortise could, of course, be made by
Get this right and success will follow. Take time to fi t the tenons in the shelf
template to the mortises in the end pattern. When the parts are routed to
the templates, the joints will work.Built-in guidance system. The fl at
area of the routed mortise acts as
a guide for the back of the chisel.
Rest the back against the cut and
swing the edge of the chisel down
to the corner (above). This shal-
low line will guide the tool in the
n e x t s t e p of mak in g t h e cu t. W i t h
the edge of the chisel in the line,
push straight down. Clean up both
end-grain surfaces of the mortise
and then fi nish the cut on the
ends. The long-grain cuts tend to
split, so shave off a little at a time
(right). A few strokes with a rasp
will fi nish the mortises.9 90-97_TuskTenBookrack.indd 94 0 - 97 _TuskTenBookrack.indd 94 3 3/25/13 9:57 AM/ 25 / 13 9 : 57 AM