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PICKING THE RIGHT CONSTRUCTION MATERIAL 51

advantages. These include ABS, acetal resin, and nylon. Their
use in robotics is covered in more detail in Chapter 9, “Work-
ing with Plastic,” for more details on using plastic materials.

METAL

The archetypal material for robots is metal. It’s among the
most expensive materials for robots— in terms of both cost
and weight— and is harder to work unless you have the
proper tools and skills. That said, metal is a must if your
robot will be bashing other robots to death in combat or if
it’s made for rugged outdoor use.
For robots, aluminum and steel are the most common
metals. Aluminum is a softer metal, so it’s easier to work
with. But steel is several times stronger, and it’s easier to
weld if you’re planning on building a large robot.
There are three general approaches to metal construc-
tion in robots, shown in Figure 5-2:

• A flat frame provides the base of the robot and lends it
support. A box- shaped frame is just what its name implies:
Figure 5-1 Expanded PVC is an ideal a 3D box with six faces. It’s well suited for larger robots or
construction material for robotics. It’s those that require extra support for heavy components.
inexpensive and lightweight, and it cuts • A shaped base is a piece of metal cut in the shape of the
and drills like wood. It comes in a variety robot. The metal must be rigid enough to support the
of colors and thicknesses to match the
needs of your project. weight of the motors, batteries, and other parts without
undue bending or flexing. Some very capable robots are
basically a piece of sheet metal on wheels, with a laptop
PC resting on top.

Robots made of wood, plastic, or other materials may nevertheless use metal (typically
aluminum) in their construction. Common metal parts include brackets, to hold pieces
together, and nuts, screws, and other fasteners.

FYI See Chapter 11, “Working with Metal,” for more details on using metal materials in your robots.

LIGHTWEIGHT COMPOSITES

Not every robot needs to withstand a winter sandstorm on Mars. A technique known as rapid
prototyping uses lightweight materials that are cut with basic hand tools, like knives and

Figure 5-2 The three basic types of
robot bases: square frame (it can actually
be made of wood, plastic, or metal), a
box frame, and a shaped base that
provides the structure for the robot’s
components.

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