One Guide, One Bit, One Setup…
It’s that Easy

The FMT Pro has several features that make mortise & tenon joints quick and easy to rout. For the serious hobbyist or small shop professional, there is simply no faster or more accurate method.  With one guide, one bit and one setup, the FMT Pro can rout both the mortise and matching tenon in just 60 seconds.  Read on to learn more.

Key Components and Construction

The most important parts of the FMT Pro are identified below. The jig is made primarily of aluminum, CNC machined to very precise tolerances, and constructed with only the highest quality materials, ensuring accuracy and ease of use.

The Jig Table
The table has several key features. It moves in any direction and its sight centers the track and guide to the desired tenon/mortise position. It also works in tandem with the sub-base/router to rout the joint. See more features below.


The movable table positions the extended sight precisely over the marked workpiece. To rout the joint, the sub-base guide pins slide in the table's pin track and around or in the center slot of the inserted joint guide. Teflon pads on both the table and sub-base make routing incredibly smooth.

Joint guides snap easily into the guide recess.

Aligning the table to the layout lines with the sight is incredibly precise.

For multiple joints, limit stops (red arrows) and posts (white arrows) are used to position the table in set, repeatable positions.
Joint Guides
The patented Leigh joint guides control the size and shape of mortise & tenon joints. Just one guide routs both the mortise and the tenon. The router/sub-base is steered around the guide to rout the tenon shape, and in the guide's center slot to rout the mortise. 21 different sizes of guides (24 metric) used with different sizes of bits produces 68 standard joint sizes from 1/16" x 1/8" up to 1/2" x 5" (79 metric, from 2 x 4 mm up to 12 x 130 mm). Custom sizes up to 1/2" x 5" (12 x 130 mm) can also be achieved.

Multiple Joint Sizes from a Single Guide

If you want to rout a joint that’s wider or narrower than the standard guide size, or if you don’t have the right guide on hand, you can use the table movement in conjunction with the limit stops to produce multiple size joints from a single guide. The 1″ and 2″ tenons shown opposite, were both routed using the same 1-1/2″ guide.

One joint guide can rout different joint sizes.

Guides for Special Joints on the FMT Pro

Y-AXIS MORTISES
In instances when mortises
need to be routed at 90°
to the clamp plate, this
guide does the trick.
Learn more >

LOUVER DOORS
Make beautiful louver doors with
these left or right matching pairs
of guides.
Learn more >

SQUARE TENONS
Square tenons are often used
for replicating period furniture.
Learn more >

Leigh Brand Router Bits
A Leigh brand 5/16" (8mm) HSS spiral upcut 1/2" shank bit is included with the FMT Pro. More bit sizes are available in HSS or solid carbide. Solid carbide bits are stiffer, rout cleaner and last longer than HSS bits. A bit set is available for savings over individual bits. Learn More >

A Leigh brand 5/16" (8mm) HSS spiral upcut 1/2" shank bit is included with the FMT Pro. More bit sizes are available in HSS or solid carbide. Solid carbide bits are stiffer, rout cleaner and last longer than HSS bits. A bit set is available for savings over individual bits.

Universal Sub-Base

The universal sub-base is designed to fit virtually any router. Fitted with your router and a bit, the sub-base works in conjunction with the table to rout the mortises and tenons. Read on to learn about router compatibility and joint fit adjustment.
 

The two guide pins projecting from the universal sub-base steer the attached router in the right track of the table and in or around a guide in the left guide recess, to rout the joints.

Router Selection

The FMT Pro can accommodate most popular brand routers. It can only be used with plunge routers, and will not work with fixed-base routers. A router with a 1/2" collet is required to get the most from your jig.

FENCE ROD MOUNTING
Most routers attach to the sub-base using
two fence rods held in place by U-posts.

DIRECT SCREW MOUNTING
Some routers attach directly to the
sub-base using two or three of the
included Leigh screws.

Routers That Fit the FMT Pro

The following is a list of routers compatible with the FMT Pro. It is updated on a regular basis as new routers are available. If your router is not listed, a quick toll free call to Technical Support, 800-663-8932 in USA/Canada, is all that is necessary to determine a mounting solution.

Joint Fit Adjustment

The left guide pin projecting from the universal sub-base does more than steer the router — it's adjustable up or down in 0.001"(0.025mm) increments for perfect joint fit.
 

 
Turning the tapered left guide pin knob up against the tapered guide produces a smaller tenon and larger mortise, just as turning it down produces a larger tenon and a smaller mortise. Each 1/8 of a turn adjusts the glue line fit by 0.001" (0.025mm).

Clamping and Mounting

Mortise and tenon workpieces are securely mounted onto the jig's machined clamp plate with Leigh's heavy duty cam-action speed clamps. An adjustable side stop fence provides accurate tenon board positioning and a mortise steady.

CLAMPS Workpieces are held securely against the clamp plate by 3" Cam-action Speed Clamps. Quick to mount in the T-slots and keyholes, they are extremely strong and easily adjustable.

CLAMP PLATE SURFACE Workpieces are secured in place against the clamp plate's machined, non-marring, textured surface.

ANGLED CLAMP PLATE The clamp plate can be tilted
up to 30° for angled joints.

TENON POSITIONING The adjustable side stop fence provides accurate tenon workpiece positioning. The short end acts as a T-square against the clamp plate edge.

MORTISE STEADY The side stop fence provides additional support for smaller mortise workpieces.

ANGLED SIDE STOP The side stop fence (secured to clamp plate in reverse position) can be angled up to 45° for angled joints.

Angled Joints

The FMT Pro makes chair joints easy to rout. Its unique design with adjustable side stop and tilting clamp plate makes for simple setup of multiple angled joints.

Chairs are often made using single and compound angled tenons (mortises are not angled).

SINGLE ANGLED TENON (using angled clamp plate).

SINGLE ANGLED TENON (using angled side stop).

COMPOUND ANGLED TENON (using angled clamp plate and angled side stop).

Multiple Joints

For an even stronger mortise & tenon joint, double, quadruple, or even triple joints are remarkably simple to make with the FMT Pro and can be used in workpiece thicknesses up to 3" x 5-1/2" (76 x 140mm). Their strength is largely due to the greater glue surface they provide. Simple table movements using limit stops provide accurate positioning of each mortise and tenon.


Double in line mortise & tenons add strength to table rails.


For multiple joints, limit stops (red arrows) and posts (white arrows) are used to limit the travel of the table.

Small and Miniature Joints

Due to the accuracy of the FMT Pro, it can rout joints not only smaller than 1/4" (6mm), but so tiny they're almost beyond belief — all with the same easy setup and adjustable fit you expect in larger joints. For more info, see How To page.

The matchsticks feature mortise & tenon joint sizes of .040" x .095" and .013" x .053"! The smallest mortise & tenon was routed with 1/64" (0.4mm) mortise and 31/64" (12.3mm) tenon machine tool bits. These matchstick joints actually creak when assembling! CNC machine cutters were used to make these incredible joints.

The 7-1/2" (190.5mm) ebony and holly ladder leaning against a 1/2" x 5" (12 x 127 mm) tenon has ebony wedged tenons 1/16" x 1/8" (1.59 x 3mm).

Miniature furniture parts such as small cabinet door frames, doll house architecture and furniture, and very accurate miniatures all call for mortises and tenons as narrow as 1/8" (3.2mm) or less.

Production Routing

The FMT Pro is ideally suited for production routing. Using a larger bit to rout the tenons can speed up production dramatically. For more info see the How To page

Production chairs in western red cedar, Stockton, CA USA Steven A

 

Production run of storm windows to replace original windows at an estate in Milwaukee, WI.

 

 

Outrigger Beams

The FMT Pro comes with two bars for attaching shop-made outrigger beams to the jig. Outrigger beams increase the capacity, speed and accuracy of the Leigh FMT Pro by enabling successive mortises on one workpiece and repeatable mortises on multiple workpieces.

 
Outrigger bars are quick to install and shop-made beams are easy to make with simple instructions in the user guide.
 
A stop block(s) clamped on the beam enables repeatable accurate positioning of multiple workpieces.
With the outriggers set and the table sighted for one joint, any number of similar joints may be routed without marking or removing the router from the jig.
 

Index marks are drawn on the outrigger edge for successive mortises in one workpiece.
 
Built-in Dust Collection Port

The built-in vacuum box has a tilting 1-3/8" dust collection port that can be stepped up to 2-1/2" or down to 1" with the two included adaptors.

 

Technical Specifications
CAPACITIES
Single Mortise & Tenon Joints
MIN MAX
1 Workpiece Thickness - 3"(76mm)
2 Tenon Workpiece Width - 5-1/2"(140mm)
3 Mortise Width/Tenon Thickness 1/16"(1.6mm)* 1/2"(13mm)
4 Mortise Length/Tenon Width 1/8"(3.2mm)* 5"(127mm)
5 Mortise Depth/Tenon Length Project based 2-1/8"(54mm)
* See Small and Miniature Joints
Double (In Line) Mortise & Tenon Joints
MAX
1 Workpiece Thickness 3"(76mm)
2 Tenon Workpiece Width 5-1/2"(140mm)
3 Mortise Width/Tenon Thickness 1/2"(13mm)
4 Mortise Length/Tenon Width 2"(51mm)
5 Mortise Depth/Tenon Length 2-1/8"(54mm)
Double (Twin) Mortise & Tenon Joints
MAX
1 Workpiece Thickness 3"(76mm)
2 Tenon Workpiece Width 5-1/2"(140mm)
3 Mortise Width/Tenon Thickness 1/2"(13mm)
4 Mortise Length/Tenon Width 5"(127mm)
5 Mortise Depth/Tenon Length 2-1/8"(54mm)
Quadruple Mortise & Tenon Joints
MAX
1 Workpiece Thickness 3"(76mm)
2 Tenon Workpiece Width 5-1/2"(140mm)
3 Mortise Width/Tenon Thickness 1/2"(13mm)
4 Mortise Length/Tenon Width 2"(51mm)
5 Mortise Depth/Tenon Length 2-1/8"(54mm)
Triple Mortise & Tenon Joints
MAX
1 Workpiece Thickness 3"(76mm)
2 Tenon Workpiece Width 5-1/2"(140mm)
3 Mortise Width/Tenon Thickness 1/2"(13mm)
4 Mortise Length/Tenon Width 2"(51mm)
5 Mortise Depth/Tenon Length 2-1/8"(54mm)
Maximum Size Workpiece For Mortising To Center
using STANDARD procedure and shopmade bracket
MAX
1 Mortise Workpiece Thickness Up to 4-5/8"(115mm)
Maximum Size Workpiece For Mortising To Center
using NON-STANDARD procedure and shopmade bracket
MAX
1 Mortise Workpiece Thickness 4-5/8" to 6-1/2"
(115mm to 165mm)
JIG SIZE AND WEIGHT
FMT PRO CARTON
Length : 16-1/2" (419mm) 21-1/2" (546mm)
Height : 8" (203.2mm) 13-3/4" (362mm)
Depth : 11" (279mm) 14-1/4" (349.25mm)
Weight : 28.4 lbs (12.9 kg) 30 lbs. (13.6 kg)
STANDARD JOINERY
Single, Double, Triple and Quadruple Joints
Through Joints
Massive Joints
Simple Angled Joints
Compound Angled Joints
Floating Tenons
Doweling
Miniature Joints
Louver Door Joints (optional)
Square Tenon Joints (optional)
Y-Axis Mortise Joints (optional)
 

IN THE BOX
FMT Pro Jig includes:
Jig Body, Clamp Plate, Table with guide track
Universal Sub-base (attaches to virtually any
plunge router) Includes router hold-down
rods and related hardware
Outrigger Bars with mounting hardware
Jig Mounting Hardware
1/8" Ball End Hex Screwdriver
Square Drive Screwdriver (No.2 Robertson)
5/64" Hex key (for sight adjustment and Festool router attachment
Five 5/16" Joint Guides and Stand
(5/16" x 1/2", 3/4", 1", 1-1/4" and 1-1/2") or six 8mm Guides
(8 x 15, 20, 25, 30, 35 and 40mm), which can make over 21
(24 metric) sizes of mortise & tenon joints
Two Cam-action Speed Clamps
5/16" (8mm) HSS spiral upcut bit with 1/2" shank
Centering mandrels, Inch (1/4", 1/2") Metric (8mm, 12mm)
Adjustable Side Stop Fence
Vacuum Box with hose adaptors for 2-1/2" and 1" hose sizes
Fully illustrated user guide.
Instructional videos are available online at Support/ Instructional Videos and User Guides page
Warranty/Registration Card
OPTIONAL ACCESSORIES

The following router bits and guides increase versatility. Available in accessory kits for greater savings.

Solid Carbide Bits, 8 additional
High Speed Steel Bits, 8 additional
Guides, 16 additional

Louver Door Guides
Square Tenon Guides
Y-Axis (Right Angle) Mortise Guides
Learn more

JIG COMPARISON

Leigh Mortise & Tenon Jig Comparison
See comparison overview
See detailed comparison chart