Page 81 - Robot Builder's Bonanza

50 BUILDING ROBOT BODIES— THE BASICS

Your budget and construction skills, plus the availability of heavier- duty tools, will also influ-
ence your choice of materials. It takes a lot less sweat to use a 1/4″ sheet of plywood or 1/8″
plastic than it does to cut or drill aluminum and steel. And it’s easier still to make a robot using
foamboard you purchase at the craft store.

• Wood. Wood is easy to work with, can be sanded and sawed to any shape, doesn’t conduct
electricity (avoids short circuits) unless wet, and is available everywhere.
• Plastic. Pound for pound, plastic has more strength than many metals, yet is easier to
work with. You can cut it, shape it, drill it, even glue it. Some unique plastics might be
harder to get unless you live near a well- stocked plastics specialty store; mail order is a
great alternative.
• Metal. And by metal we’re talking mostly aluminum here, though copper and brass sheets
and tubes are commonly available in hobby stores. All three are great for building robots.
• Lightweight composite materials. Art supply stores stock what’s known as “foamboard,”
also called Foam Core, a popular brand. Foamboard is a sandwich of paper or plastic glued
to both sides of a layer of densely compressed foam. Heavy- duty cardboard and lightweight
plastic board used to make signs are also contenders.

Let’s take a closer look at these. Even more details on these construction materials are
found in later chapters.

WOOD
If Noah can build an ark out of wood, it’s probably good enough for robots. Wood is reason-
ably inexpensive and can be worked using ordinary tools.
Avoid soft “plank” woods, like pine and fir; and instead select a hardwood plywood
designed for model building. Though more expensive— about $7 to $10 for a 12″ 12″
square— this material is superior for robot building. These plywoods are less likely to warp,
crack, or fleck. They’re available at hobby and craft stores.

FYI See Chapter 7, “Working with Wood,” for more details on using wood in your robots.

PLASTIC
There are literally thousands of plastics, but don’t let that alarm you. For robotics, there are
just a small handful of plastic materials that are both affordable and readily available. These
same plastics also tend to be the ones most easily worked using standard shop tools.
• Acrylic is used primarily for decorative or functional applications, such as picture frames
or salad bowls. It’s usually clear but also comes in solid and translucent colors. You have to
be careful of cracking caused by too much weight.
• Polycarbonate is similar in looks to acrylic but is considerably stronger. This plastic is a
common substitute for window glass; because of its increased density, it’s much harder to
work with and is more expensive.
• A special type of PVC that comes in sheets, called expanded PVC, is ideal for making small
and medium- size robots. An example robot made with PVC is shown in Figure 5-1. It’s
easier to work with than either acrylic or polycarbonate plastic.
• Specialty plastics. And last, there are a couple of plastics that are a bit harder to find (you
get them at specialty plastics outlets; check your local Yellow Pages), but they offer certain

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