Page 97 - Robot Builder's Bonanza

66 MECHANICAL CONSTRUCTION TECHNIQUES

Wood Plastic Metal
Blade Match the blade with the For circular saw: If possible, As a general rule, 3–5
thickness and grain of the use a “nonmelt” blade teeth should engage the
material. Circular saw made for plastics; if you metal. Select the blade
blades are often classified can’t find one or it’s too according to the thickness
by their application (such expensive, a high- quality of the material you’re
as “crosscut”). Use this as plywood blade will do. The cutting.
a guide. wider the kerf in relation to Use an abrasive cutoff
the thickness of the blade, tool for heavy- gauge
the better. This avoids ferrous metals.
remelting.
For hacksaw or scroll saw:
Use an intermediate pitch
blade (18–24 teeth per
inch). A wide- kerf is best.
Cooling Air cooling is sufficient, Air cooling is usually Use cutting oil or wax for
though beeswax can be sufficient. If remelting heavy- gauge metals.
used if the wood is very occurs, direct 50–75 psi air
dense. from a compressor over
cutting area.

In the preceding table, the term kerf means the width of the cut made by the blade. Many
G blades use cutting teeth that protrude to either side (often referred to as set). This makes for a
wider cut (kerf), but helps keep the blade from binding into the material. When cutting plastic, a
wide kerf helps prevent melting.

LIMITING CUTTING DEPTH
When using power saws, you can readily limit the depth of the cut by changing the height of
the blade within the tool. This is useful when you want to add channels or grooves in the mate-
rial but not cut all the way through. The following apply to sawing wood or plastic, and when
the thickness of the material is at least 1/4″—any thinner and it doesn’t much matter how
deep the cutting is.

Set the blade to route by just grazing into the material. Use this technique to
score very hard material, like polycarbonate plastic; once scored, you can
snap the pieces apart using a wood dowel placed under the score mark.
Cut grooves into thicker materials by setting the blade depth to about 1/3 to
1/2 thickness. The width of the groove is the kerf (or set) of the blade— the
width of the blade itself, plus the right and left offset of the cutting teeth.
With a full cut, the blade penetrates completely through the material.

OTHER WAYS TO CUT MATERIAL

While a saw is the most common means of cutting materials, there are other methods as well.
Select the method based on the material you are cutting and the demands of the job.

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