Page 118 - Robot Builder's Bonanza

Chapter 9

Working with Plastic

t all started with billiard balls. In the old days, billiard balls were made from elephant tusks.
IBy the 1850s, the supply of tusk ivory was drying up and its cost had skyrocketed. So in
1863, Phelan & Collender, a major manufacturer of billiard balls, offered a $10,000 prize for
anyone who could come up with a suitable substitute for ivory. A New York printer named
John Wesley Hyatt was among several folks who took up the challenge.
Hyatt didn’t get the $10,000. The material he promoted, celluloid, carried with it too
many problems— like occasionally exploding during its manufacture. While Hyatt’s name
won’t go down in the billiard parlor hall of fame, he will be remembered as the man who
helped start the plastics revolution. Celluloid was perfect for such things as gentlemen’s col-
lars, ladies’ combs, containers, and eventually even motion picture film.
Since the introduction of celluloid, plastics have taken over our lives. Plastic is sometimes
the object of ridicule— from plastic money to plastic furniture— yet even its critics are quick to
point out its many advantages:
• Plastic is cheaper per square inch than wood, metal, and most other construction materials.
• Certain plastics are extremely strong, approaching the tensile strength of such light metals
as copper and aluminum.
• Some plastic is “unbreakable.”

So you can imagine that plastic is ideal for use in hobby robotics. Read this chapter to learn
more about plastic and how to work with it. In the next chapter I’ll show you how to construct
an easy- to- build “turtle robot”—the PlastoBot— from inexpensive plastic parts.
Main Kinds of Plastics for Bots

Plastics represent a large family of products. They often carry a fancy trade name, like Plexi-
glas, Lexan, Acrylite, or Sintra. Some plastics are better suited for certain jobs, and only a
relatively small number of them are appropriate for robotics.
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