NOVEMBER/DECEMBER 1983, No. 43, $3.50 Making ... - Wood Tools

tages. First, the saw is always held at the correct angle, freeing
me from the task of sliding work and saw around in search of
the narrow notch in the bird's-mouth. Second, the saw's
hinged upper arm pivots out of the way when a blade must
be threaded through the workpiece. And third, the veneer can
be held stationary as the saw is stroked. This last feature is
handy because when the blade reaches the bottom of its
maximum stroke, it will have advanced about %4 in., offering
good control when cutting fragile or pointed parts.
As the drawing shows, I made my jig to about the dimensions
of a small, power scroll saw. The table, saw bracket and
tilting mechanism are of pine, but a good grade of :X-in. plywood
could be substituted. If unsupported, veneer will chip
on the back side as it is cut. I solved this problem by inserting
a throatpiece that slides in a I-in. wide dovetailed groove
milled in the tabletop. One end of the throatpiece is kerfed to
accommodate the blade set at 900; the other end has two
kerfs at 120, the angle I like for double-beveling.
The saw is
be
clamped to a bracket, which is in turn artached
to the table by a section of brass piano hinge. This allows the
saw angle to varied. A thumbscrew through a shopmade
aluminum bracket locks the saw at the desired angle. I made
my own barrel nut for the thumbscrew by drilling and tapping
a %-in. steel rod. A wood screw, or better yet a thumbscrew
threaded into a Rosan insert, would serve the same purpose.
The best pivot point turned out to be 15 in. from the
blade and just below the surface of the table.
If I had had access to a machine shop, I would have made
the upper arm hinge from aluminum so that it could be
smaller. As it was, I had to use wood, and maple seemed a
good choice. So that you won't have to contend with clamping
the odd-shaped pieces on the drill press, bore the blind
holes for the saw frame before you shape the hinge parts. I
didn't have the 0.515-in. (3%4-in.) bit to match the diameter
of my saw frame, but an oversize �-in. masonry bit I found
in my collecrion worked fme after I ground off a few thousandths
of an inch. For accuracy, I drilled a �-in. hole first,
and then, without changing the setup, enlarged it with my
modified bit. Not all fretsaws have tubular frames (I got
mine from Constantine's). If yours is of steel bar stock, you'll
have to modify the mounting bracket and mortise the frame
1 into the hinges.
cut
and shaped the hinge sections on my 4-in. Dremel
saw. Doing it by hand is nearly as easy. With a backsaw, saw
the angled cheeks and
1
shoulders of the male section, then
chisel the slot in the female part until you get a slip fit. For
the hinge pin, I sacrificed a %2-in. drill bit. Measuring the
overall length of the hinge and subtracring the combined depth
of the
1
two holes tells you how long a section of the saw has to
be cut out. Make sure that the blade clamps line up when you
put the saw together. fastened the hinge with sheet-metal
screws driven through the wood and into
be
the saw frame.
Installing a blade is easy. First, I clamp the jig to a comfortable
work surface, which happens to the desk in my
den. thread the blade through from the top and clamp it at
the bottom. Resting the saw handle on my knee leaves both
0
hands free to pivot the upper arm down and clamp the other
end of the blade.
Ed Kampe was a design engineer and general foreman in
precision metalworking. He makes marquetry pictures in
Zellwood, Fla.
Motor makes fretsawing fly
by Scott Littleton
12 -in. fretsaw
Worm gear
Hinge
As a marquetry beginner, I found that knife-cutting left my
.fl. hands stiff and sore, so I set out to design and build a
low-cost power scroll saw that would make a beveled cut.
Ideally, a marquetry saw's blade should operate straight up
and down. But a mechanism with a large throat to achieve
this ideal seemed beyond my abilities. Some sketching
showed me that a simple oscillating saw might work, since
the force needed to cut veneer is small and the speed need not
be great. One disadvantage of a rocking saw
(:x
frame is that the
cutting edge of the blade moves fotward and back during the
stroke. I found that with a short stroke in.), the front-toback
motion is negligible.
I built my saw the simplest way I could and just slapped it
together quickly, thinking it was an experiment to be improved
on later. It works so well that the only improvement I
may ever make is to increase the throat depth.
To make the saw, I clamped a 12-in. fretsaw between two
bolted blocks. The blocks are attached to a hinged post
mounted on a :X-in. plywood base. To remove any side play
from the saw, put the hinges in a bind, or use a piano hinge.
Up-and-down motion is achieved through a small electric
motor, a small worm gearbox (or gearmotor) and a simple
crank mechanism. After having tried several speeds, I find
that about 300 strokes per �inute is my preference. The motor
to power the unit need not be large. I've found that even
a X20-HP gearmotor (Dayton 200-RPM shaded pole gearmotor,
0
stock #2Z812, about $18.50) will cut two thicknesses of oak
veneer without noticeably slowing down.
Scott Littleton lives in Salt Lake City, Utah.
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