Leigh FMT PRO, User Manual

Page: 46 / 74

Frame Mortise & Tenon Jig User Guide
42
Chapter 6
WORKPIECE AND JOINT OPTIONS
6-3
Side-by-side double and quadruple joints of different stock
thicknesses require a packing piece (see 6-4) between the clamp plate
and tenon piece, the thickness equal to the offset of the two pieces.
For example, a 2"[50mm] tenon piece
➀
centered on a 3"[75mm]
mortise piece
➁
will require a
1
⁄
2
"[12,5mm] packing piece
➂
.
m
Never
attempt to achieve this alignment by re-sighting the joint and resetting
the
FB
limit stops. That would make it impossible to guarantee
twin-tenon to mortise alignment.
3
1 2
6-4
This packing piece should include its own side-stop fence
➀
and if required frequently, should have sandpaper glued onto its
outer surface for secure workpiece clamping
➁
.
Sight and rout the tenons in the usual way with the packing piece
in place. Then, remove the packing piece before sighting and
routing the mortises.
■
1
2
6-5
The FMT Pro table movement allows for easy routing of odd-
sized joints. For example, you may want to rout a 3"[75mm] joint
➁
and you only have a 2"[50mm] guide
➀
. Use this simple formula:
Joint, minus Guide, divided by 2 .
Example: 3" - 2"
÷
2 =
1
⁄
2
"[75 - 50
÷
2 = 12,5mm]
Cut a small block equal to the result; in this example,
1
⁄
2
"[12,5mm].
Longer and Shorter Joints
1
2
6-6 Tenons
Mark the center as before.
Position and sight the tenon
➀
, and lock the table.
Set the
FB
stops against the post
➁
.
1
2
6-7
Set the
LR
stops one at a time with the small block
between the stops and post
➀➁
. This ensures that the table move-
ment is centered about the joint center-mark on the stock. Remove
the block,
but save it
.
1 2
6-8
To rout the wider tenon:
- Move the table
right
, to the stop
➀
.
- Rout the right-hand end of the tenon
➁
.
Use a guard in the left end of the guide recess if necessary
➂
.
1
2
3