Page 138 - Robot Builder's Bonanza

Chapter 11

Working with Metal

efore the modern dependency on plastic, metal was the mainstay of the construction
Bmaterial world. Toys were not made of plastic, as they are today, but of tin.
Metal is a good material for building robots because it offers extra strength that other mate-
rials cannot. In this chapter you’ll learn how to construct robots out of readily available metal
stock, without resorting to welding or custom machining.

All about Metal for Robots

Metal is routinely broken into two broad categories: ferrous and nonferrous.

• Ferrous metals are made from iron (Fe, from which “ferrous” is derived, is the symbol for
iron on the Periodic table of elements).
• Metals other than iron are nonferrous. This includes copper, tin, and aluminum.

When you buy a piece of metal, you’re seldom buying the stuff in its pure form. Instead,
metal is almost always processed with other metals. The resulting material is called an alloy.
Different alloys provide different properties for the metal. For example, there are aluminum
alloys specifically designed for casting, and others intended for machining parts.

ALUMINUM
Aluminum is the most common metal used in robot construction projects, partly because of
cost and partly because it is strong yet lightweight. It’s also one of the easier metals to cut and
drill, and it requires only a modest assortment of tools. The aluminum you buy at the hardware
store is actually an alloy; raw aluminum (which is manufactured from bauxite ore) has little
commercial value as a finished metal. Rather, the alumina metal is alloyed with other metals.
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