Trend MT/JIG User guide

T

he mor tise and
tenon joint is one of
the oldest and
undoubtedly the

most frequently used
joint in woodworking. There are
many versions of the joint and
equally many different ways of
cutting it. Router users tend to
make jigs; one for the mor tise
and one for the tenon. Trend

have now introduced a jig that
cuts both mor tise and tenon.
Moreover, it cuts both halves of
the joint from a single setting
of the jig. By setting up to cut
the tenon, the jig is
automatically set to cut the
mortise. This means that the
orthodox method of cutting the
mortise first and then making
the tenon to fit it no longer

applies; it is convenient to cut
tenons first.

The capacity of the jig, for
orthodox mor tise and tenon
joints, is timber of

1

⁄2in to 2in
thickness and mortise widths
of

3

⁄16in to 5⁄8in. These
dimensions are given with
approximate metric equivalents
on the packaging and give an
indication that the jig is of

North American origin. Other
unmistakable signs are that all
the cutters and guide bushes
are in imperial measure and
there is an optional set of the
American ‘Por ter Cable’ pattern
brass guide bushes with scr ew
rings to fasten them.

Photo 1 above shows the
components of the jig and its
accessories. The instructions

52

Routing 50

On Test

Trend

Mortise and Tenon Jig

Ron Fox is one of the first to try out Trend’s latest new product designed to simplify
mortise and tenon joint cutting with the router

1

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August/September 2002

53

tell you to screw it to the
bench, but I mounted the test
model on a length of MDF and
clamped this to the bench top.
Whichever way you do it, the
essential thing is that the jig is
mounted on a firm, stable
sur face.

Tenons

The jig is based on sliding
plates with which are used with
guide bushes and cutters of
different diameters according
to the size of the joint. Photo 2
shows it being set up for
cutting the tenon. The marked­up workpiece is clamped
vertically in the jig, and the two

plates of the template are
being set with the special
setting bar that comes with the
jig. Timber should be marked
on its face and clamped in the
jig with the face side inwards
i.e. against the ver tical plate. It
is also impor tant that the top
plate should be parallel to the
sides of the timber when
centring. If it is not, mortises
and tenons will be cut skew.

All tenons are cut with a

5

⁄8in
diameter straight cutter; the
various widths of tenon are
controlled by the choice of
guide bush. The template, with
its rounded inner ends, gives a
rounded tenon which will fit
into the rounded mor tise
without further handwork.
However, the plates of the
template can be reversed to
give square-ended tenons if
desired.

With the jig set up, a guide
bush is selected to give a
tenon with its width as near as
possible equal to one-third the
thickness of the workpiece. A
chart on the setting-up bar
gives the relationship between
tenon width and guide-bush
diameter. The tenon widths

possible equate to the dif ferent
diameter mor tise cutters.

Five plastic guide bushes
and one steel one are supplied
as standar d with the jig, plus a
guide bush collar for cutting the
tenons. These are standard
Trend-fitting bushes and will
attach directly to a wide range
of routers, but for non Trend­compatible models the Trend

Unibase or the circular sub­base can be used to adapt the
bushes.

With the appropriate guide

bush and the

5

⁄

8in cutter in the

router the tenon is cut in a
series of light passes
proceeding in a clockwise
direction around the template.
On the face of it, this breaks
the rule of ‘anti-clockwise

On Test

Trend 0800 487363
www.trendmachinery.co.uk

Prices
MT/JIG £176.19
Set/MT1 Cutters £46.94
MT/DUSTKIT £11.69
These are list prices and
include VAT.

Further

information

The jig being set up for a tenon

The resulting tenon. Note rounded ends

Mortise being cut

2 3

4

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54

Routing 50

around the outside of the
figure’ but if you try a test cut
in an anti-clockwise direction
you are likely to get bad break­out around the edges of the
workpiece. It is essential that
you keep the guide bush firmly
against the edge of the
template. If you wander away
from the edge you will remove
some of the tenon. Photo 3

shows the completed tenon in
the jig. Note the rounded ends,
ready for the rounded mortise.

Cutting technique

We found that the best way of
cutting the tenon was in a
series of light cuts, each cut
being set to about 5mm with
the stop bar. The cut was
plunged into the work with the

router moving for ward - a
technique sometimes called
‘ramping’ - and pushed down to
the turret stop without locking
the plunge. This gave an
easier, cleaner cut than by
locking and unlocking the
plunge.

Mortises

To cut the mortise, a cutter of
the specified diameter is
fitted to the router and the
guide bush is changed for the
1in steel bush fitted with the
2

1

⁄8in collar. This collar fits
snugly in the template and
guides the cutter straight up
and down the middle of the
workpiece. The plates of the
template control the length of
mortise without any re-setting
after cutting the tenon.

The marked-up workpiece is

clamped horizontally in the jig
with the mor tise being centr ed
between the template plates.
An extra clamping position
caters for mor tises cut in the
end of the workpiece.

The depth of cut is set ver y
slightly deeper than the tenon
length and the mor tise cut in a
series of light passes. It helps
if a spar e piece of wood is
clamped in the vertical clamp
tight up under the mor tise
piece to suppor t the workpiece
when the router is plunged.

Photo 4 shows the cutting of
the mortise matching the
tenon shown in photo 3. The
collar on the guide bush is
clearly visible.

Photo 5 shows the two
halves of the joint, illustrating
clearly the rounded ends of
both mortise and tenon.

On Test

A set of fourteen guides bushes in imperial measure, ranging
from

3

⁄8in to 15⁄16in is available as are a number of steel guide
bushes sold separately. There is also a set of ‘Por ter Cable’
American-standard brass guide bushes.

Finally there is a dust extraction kit which attaches to the

jig and connects to an extractor.

Other options

The two halves of the joint, showing the rounded ends of both mortise and tenon A tenon piece being checked for square after ‘shooting’

Angled tenons cut in the jig

5

7

6

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More on tenons

One useful trick you can play
with the jig is to use the router,
set up in tenon mode, to
‘shoot’ the end of the
workpiece square and to bring
it to exact length. Depth of cut
is set to just a millimetre or so
and the cutter taken around
and across the top of the
workpiece, allowing the guide
bush to come away from the
template. This is a trick I use
extensively with the WoodRat
and it works nearly as well with
the Trend jig.

Photo 6 shows a tenon piece
being checked for square after
shooting.

Different kinds of tenon can
be cut with the jig. Angled
tenons are cut by moving the
vertical clamp against a
printed scale to the required
angle. Alter natively the main
back plate of the jig can be
tilted to give angled tenons in
the other plane. A more
sophisticated touch is that
compound-angle tenons can
be cut by setting both the
vertical clamp and the tilting
back plate. Photo 7 shows

two angled tenons cut with
the jig.

The tenon normally produced
by the jig is shoulder ed with
rounded ends. Square tenons,
both shouldered and plain, can
also be produced by the
simple expedient of reversing
the plates of the template so
that the straight ends are on
the inside.

Photo 8 shows square tenons
cut with the plates reversed.
With these, the ends of the
mortise are still, of course,
rounded. You then have the
choice of either squaring the
ends of the mor tise or rounding
the tenon with a rasp or file.
Neither of these appeals to me
but alter native methods destroy
the automatic setting-up for the
two halves of the joint.

Dowelling

The jig can make dowelled
joints as well as mor tises
and tenons. Holes in the
plates take the

5

⁄

8in guide

bush supplied. The cutter is
chosen to match the
diameter of the dowels being
used. The workpiece is

marked up and positioned by
means of notches on the
holes in the plates. The
dowel holes are drilled in a
series of plunge cuts with the
work held in the same way as
for mor tises and tenons.
Photo 9 shows the vertical
component of a dowelled
joint clamped in the jig, with
the other half of the joint
visible on the top plate.

Cutters

A set of five long-reach straight
cutters SET/MT1 is available
for use with this jig. Diameters
range from

1

⁄4in to 5⁄8in and the

cutters are available on

1

⁄4in or
8mm shanks. If you have
suitable sized spiral cutters
they would give even better
cuts, particularly for mor tises
and dowels, but would be
rather more expensive.

On Test

This is a jig that can cut a wide range of mortises and tenons
with just one setting of the template. As such it will improve
both the speed and accuracy of these joints. In particular it
will encourage users to tr y various forms of angled joints e.g.
for chairs.

If you have the luxury of two Trend-compatible routers, you
can become even more productive by installing one cutter
and guide bush in one router for the tenons and another guide
bush and cutter in the other for the mortises.

I am not sure how long the plastic guide bushes will last
against the sharp edges of the template. If I were going to
use this jig a lot - and I would not spend over £200 on it if I
were not - I would invest in the steel bushes offered as
optional extras.

The ability to make accurate dowelled joints with ease will
probably make users of the jig devote more attention to this
somewhat neglected joint.

The verdict...

Square tenons cut with the plates reversed

A dowelled joint. The vertical component is clamped in the jig

8

9

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