Page 104 - Robot Builder's Bonanza

THE WOODCUTTER’S ART 73

60° cuts

45° cuts

72° cuts

Figure 7-3 By making alternative
cuts at the corners you can produce
Figure 7-2 Lop off the corners of square wood pieces to hexagon and pentagon bases. You’ll
streamline the shape of your robot. With all four corners cut, you probably want to use a simple protractor
end up with an octagon. The shape of the octagon depends on (available at any school or office
how much of each corner you remove. supply store) to measure the angles.

and 7-3 show some variations on a theme. These more elaborate shapes don’t take that much
longer to produce— just a few minutes per cut, and you’ll make a better robot.

• To make an octagon (eight- sided) base, cut the corners off at 45°.
• To make a hexagon (six- sided) base, cut the corners off at 60°.
• To make a pentagon (five- sided) base, cut the corners off at 72°.

G If you have a heavy- duty motorized sander, you can lop off the corners by sanding rather than
cutting. This is usually a lot quicker. Start with a coarse sandpaper (see the section later on in
this chapter about sanding). As a final step, use a fine sandpaper to make the edges smooth.
Lopping Off Even More Corners
You can approximate near circles by cutting off more corners. Eight- sided octagons with their
corners lopped off (chamfered) make 16- sided “circlettes,” as shown in Figure 7-4. And as
shown in Figure 7-5, chamfered pentagons produce 10- sided shapes; chamfered hexagons
make 12 sides.
To make these cuts, mark directly on the wood (you don’t have to be precise— to the near-
est 1/4″ is usually fine), or use a piece of graph paper lightly glued to the wood. You can use
paper paste— the kind you ate in grade school— or a nonpermanent glue stick.
“But I wanna make a circular base!” That’s fine, but you’ll need some special tools if you don’t
want it to look like a very bad shop class reject. Circle cutting jigs are available for power
G routers and jigsaws. The one for jigsaws is fairly easy to use and is the least expensive. It works
just like a beam compass.
Start by drilling a hole in the approximate center of the wood, then adjust the circle cutter to
one- half the diameter of the circle you want. For instance, to make a 6″ circle, you adjust the

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