Leigh Super12, User Manual, Page: 21 / 86

Wood Preparation
SUPERJIG - CHAPTER 6
"Garbage In - Garbage Out"...
This adage of the computer age stands equally true for dovetail jigs.
6-1
It is vital for accurately aligned joints that stock used on the
Superjig should be prepared straight, flat, of even thickness and equal
widths, with square ends and edges. Note that plywood is generally unsuit-
able for routing because of tearout problems.
90°
90°
6-4
You will want to test the jig, so prepare some
3
⁄
4
" x
5 1 ⁄
2
"[20x140mm] boards. Cut them to length as you need them
for the jig tests you want to perform. Use them for practice with
the jig’s various joint modes so you can see how the different
modes work.
Remember, though, that two boards of different
thicknesses can be joined just as easily.
90°
1
2
3
15
6-2

Check for squareness: stand both pieces vertically on a flat
surface. Make sure side edges are flush at bottom and top

. Turn one
piece around on its end  . If side edges are flush top to bottom  ,
the boards are square. If not,
➃
; cut two that are.
90˚
90˚
90˚
90˚
1
4
2
3
6-3

Dovetail joints are intended for joining end-grain to
end-grain 
.
Attempting to rout dovetails in side grain

will not
work because:
A. The wood will tear out badly when routing.
B. The pins and tails will easily break off across the short grain
 ,
either during or soon after assembly, when the boards start expand-
ing and contracting at different rates.