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So You Want to
Build a Robot
Robotics is a wonderfully diverse
science. It mixes mechanics
with computers, mathematics,
electrical design, programming, and
a number of other sciences — all
wrapped up in a package that’s fun to
build and watch. If you’re just starting
out, though, the vast breadth of
technologies that you need to master
can appear daunting. Fortunately,
robotics is a piecemeal type of
endeavor; you don’t need to become
an expert in all aspects all at once.
In this installment of Robotics
Resources, we’ll touch upon several
main points of interest you’ll need to
be familiar with if you want to plan,
construct, and operate your first robot.
Of course, space limitations mean we
can’t provide in-depth coverage of
everything in this one column. To
further your study of the robotics arts,
you are advised to check out back
issues of this magazine and Nuts &
Volts, both of which are available in
convenient CD-ROM electronic format.
Robot Bodies
The simplest robot body is a printed
circuit board (PCB) or solderless
breadboard, and there are a number of
interesting amateur robots that use
this approach. Basically, a platform of
some type is used to build onto. This
platform is usually plastic, wood, or
metal. I have a particular fondness for
plastics, because plastic tends to be
cheap and easy to work with using
standard shop tools. Of all the
62 SERVO 12.2008
available plastics, I prefer two types,
both of which are available in sheet
form; you can purchase it online and
at many plastics specialty shops:
ABS (acrylonitrile butadiene
styrene). ABS is really a glossy,
translucent plastic that can take on
just about any color and texture. It is
tough and hard, and yet relatively
easy to cut and drill.
PVC (polyvinyl chloride). PVC is
an extremely versatile plastic best
known as the material used in fresh
water plumbing and outdoor plastic
patio furniture. Usually processed with
white pigment, PVC is actually clear
and softens in relatively low heat.
It is available in many colors and in
convenient sheet form. PVC is
extremely easy to cut and drill, and
almost impervious to breakage.
In a pinch, you can use acrylic or
polycarbonate plastic sheets, both of
which are commonly found at home
improvement stores. These plastics are
harder to work with than either ABS
or PVC, and in the case of acrylic, can
crack when you drill into it. They also
tend to collect static electricity a bit
more than other plastics, but their low
cost and accessibility make up for
these minor inconveniences.
If strength isn’t paramount, you
can find thin sheets of styrene at most
hobby stores. It comes in white and
in a variety of thicknesses. You can
readily drill and cut it to size. Of
course, let’s not forget wood and metal.
Wood is universally available, reasonably
low cost, and easy to work with using
ordinary shop tools. Hardwood plywoods — which are the recommended
wood for most robot bases — are
sturdy and strong. On the downside,
wood are not as robust as plastic or
metal. It can warp with moisture — it
should be painted or sealed — and it
can crack and splinter under stress.
Hardwood plywood for making
solid bases, is available in various
thicknesses, with 1/4” being a good
all-around choice for a robot under
10” in diameter. Even smaller robots
can use the 1/8” or 5/32” thickness.
Hardwood plywood is routinely available
at craft and hobby stores, as well as
many home improvement stores. You
can buy it in convenient cut-down sheets
of 24” x 24” (and even smaller). One
common name for hardwood plywood
is “aircraft plywood,” as it is used in
the construction of model airplanes.
Metals are routinely broken into
classifications of ferrous and non-ferrous. All ferrous metals are made
with iron. They’re called ferrous
because the symbol for iron in the
periodic table of the elements is Fe.
Obviously, all metals other than iron
are non-ferrous. This includes copper,
tin, aluminum, lead, titanium, and
zinc. Of all the metals available,
aluminum is the most common metal
used in robot construction projects,
mainly because of lower cost, but also
because it is strong yet lightweight.
It’s one of the easier metals to cut
and drill, and requires only a modest
assortment of tools. The aluminum
you buy at the hardware store is
