Tenoning jigs make the
complicated world of
mortise-and-tenon joinery a
lot simpler. I’ve used a homemade
wooden jig for years. I
stand a rail upright on the
tablesaw and clamp it to a tall
box that slides on my fence.
Most shop-made jigs have two
drawbacks, though. First, they
must be modified for different
types of joints. Second,
your fist is the only way to
make a fine adjustment to the
tablesaw fence. I kept telling
myself to look into something
better, but the only commercially
made jig available a few
years ago, the venerable Delta
34-172, didn’t tilt and was
hard to adjust.
A new generation of
redesigned jigs has changed
everything (see Chart, right). They are fully adjustable and
are extremely accurate.
They fit both left- and right tilt
saws. After trying seven
different models, I’m ready
to honorably retire my beat up
wooden jig and move on.
Most Tenoning Jigs Are Alike
All seven tenoning jigs I tried
are surprisingly similar. Remove the
handles, paint all the jigs the same color
and you would have a hard time telling
them apart. Taking a closer look,
though, I did find some subtle but
important differences. Let’s examine
their common features first.
■ Work support. This 5-in.-wide by 6-in.-tall
cast-iron plate holds the workpiece. It tilts from 0 to
17 degrees (see photo, page 86, left). You can cut
steeper angles by tilting the saw blade. On a left-tilt
saw, I turn the jig around and run it in the right-hand
miter slot when I tilt the blade for steeper angles.
This may not work on all saws, however.
■ Clamp arm. This adjusts forward or backward a
total of 2 in. to center the clamp on the workpiece.
■ Backstop. The backstop tilts backward from 0 to
45 degrees (see photo right).
■ Sliding table. The table moves 2-3/8 in. to adjust
the distance between the blade and work support.
■ Coarse adjustment. Loosening a knob allows you
to slide the table. Many times, though, you must
strike the table with your hand to get it going. That
gets old real fast. Lubrication doesn’t help much.
■ Fine adjustment. Turning a knob allows you to
fine-tune the sliding table’s position. One rotation of
the knob moves the table a bit less than 1/16 in. The
fine adjustment works so well that I usually skip using
the coarse adjustment.
4 User-Friendly Features
Some jigs have additional features that make them
easier to set up, adjust and use (see Chart, right).
■ Adjustable guide bar. Some guide bars can be
adjusted to fit tightly in your saw’s miter slot. This
must-have feature increases accuracy by preventing
the jig from wiggling as you cut a tenon. The adjustment
consists of a pair of set screws in the guide bar,
similar to those on premium miter gauges.
■ Above-jig guide-bar alignment. You must align a
new jig so that it’s parallel to the saw blade by shifting
the guide bar’s position. This is a lot easier on
jigs whose adjustment screws are accessible from
above. On other jigs, the screws are below the sliding
table, so you must remove the jig from the saw each
time you shift the guide bar. That’s very awkward.
■ Rear handle on table. For the most accurate cuts,
I prefer jigs that have at least one handle mounted on
the sliding table (see photo, right). On other
jigs, both handles are located on the work support. As
you’re cutting a tenon, I find that you can inadvertently
twist the work support by pushing too hard on
one or both of these handles. That can ruin a cut.
■ Front-mounted handle. Only one jig, the Delta
34-184, has a handle in front (see photo, above
right). I think it’s a great idea.
The seven tenoning jigs I tested are very similar to
one another, even though their prices vary quite a lot
(see Chart, below). They all work very well. Some jigs
have a few important improvements for easier setup
and more accuracy. The least expensive jig, the
Grizzly H7583, has most of these good features,
as do the Woodcraft 144755 and the
Delta 34-183. For the best value in a tenoning
jig, get the Grizzly.
The most expensive jig, the Delta 34-184,
has two features that make it the most convenient
model to use right out of the box. First, it’s the only
jig with two handles on the sliding table. Other jigs
have one or two handles on the work support.
Pushing on these handles can cause the support to
wiggle during a cut. For most cuts, the wiggle is so
small that it’s not a big deal, but for cuts that must
be very precise, it’s a concern. Using both handles
on the sliding table, I made more accurate cuts with
the Delta 34-184 than using other jigs. The second
feature is a fine-adjustment mechanism that’s graduated
for fine-tuning a setting. Each line on the
fine-adjustment knob indicates that you’ve shifted
the work support by about .004 in.
6 Joints You Can Make with a Tenoning Jig
Tenoning jigs do much more than simply make
straight tenons. You can create other joints by
tilting the jig, leaning the workpiece backward or
using a dado set. Here are a few examples:
■ Angled tenon. This complicated joint is often
used on chairs when the seat is wider in front than in
back. Angled tenons and shoulders go on the rails
connecting the front and back legs. Before getting a
tenoning jig, I couldn’t figure out how to quickly
machine all those angles, so I slowly cut these joints
on the bandsaw and by hand. Using a dado set and a
tenoning jig, however, I can cut both the tenon and
its shoulders with a single setup.
■ Open mortise and tenon. This joint is best cut
with a dado set, too, to form the mortise’s bottom
with one pass. The tenon’s length is limited by the
maximum height you can raise your dado set above
the saw’s table—about 2-1/4 in. for an 8-in. set,
1-1/4 in. for a 6-in. set.
■ Mitered end lap. This elegant door joint is
mitered above and half-lapped below, for additional
glue surface. Use a general-purpose or combination
blade for all the cuts. Run a groove inside both
pieces to receive a panel.
■ Splined miter. Use a dado set to cut these
grooves. They can be wider and deeper than grooves
made using a slot cutter on a router table.
■ Scarf joint, low-angled miter or long bevel. You
can’t cut steep angles like these with a board lying
flat on the tablesaw or a miter saw, but they’re no
problem when the piece is held upright in a tenoning
jig. A scarf joint is used to make one long piece
from two shorter ones. A low-angled miter, less than
45 degrees, is used on triangular boxes. A long bevel
is a design detail, rather than a joint. You’d use it to
taper the end of a cleat under a tabletop or the foot
of a trestle base. The bevel’s length is limited by the
maximum height a 10-in. blade can be raised, which
is about 3-1/4 in.
This story originally appeared in American Woodworker September 2006, issue #123.
September 2006, issue #123
Purchase this back issue.
Click any image to view a larger version.
All tenoning jigs are
with comparable features
Even the least expensive
model will give
you excellent results.
Every tenoning jig has a tilting work support for cutting
angled tenons, scarf joints, low-angled miters or bevels.
Caution: The blade guard must be removed when
using a tenoning jig. Use both handles.
The backstop on every tenoning jig tilts for cutting
grooves or tenons on mitered pieces. This jig, the Delta
34-184, is the only one with a front-mounted handle. This
handle makes it much easier to push the jig without wiggling
the work support.
7 Tenoning Jig Recommendations
6 Joints You Can Make with a Tenoning Jig
This remarkable jig cuts all these tenons with exquisite precision.