Page 145 - Robot Builder's Bonanza

114 WORKING WITH METAL

use these to make ersatz shaft couplers, for example, to match a small shaft to a larger wheel
hole. In fact, Chapter 24, “Mounting Motors and Wheels,” discusses this very topic.

The Metalsmith’s Art

One reason to use metal for your robot is that it’s stronger. It also looks pretty cool— though
to be fair, you can get plastic that looks like metal, but that’s beside the point. Another key
benefit is the longevity of a metal or frame; it simply lasts longer. Even if your robot falls off
the table or gets mauled by the dog, at least its body will remain intact.
But while metal provides a resiliency that wood and plastic cannot match, it’s harder to
work, costs more, and weighs more. Choices, choices.
As first discussed in Chapter 6, “Mechanical Construction Techniques,” to cut metal you
should use a hacksaw outfitted with a fine- tooth blade—24 or 32 teeth per inch. Coping saws,
keyhole saws, and other handsaws are generally engineered for cutting wood, and their blades
aren’t fine enough for metal work.
You’ll probably do most of your cutting by hand. When cutting pieces for a frame you’ll
want a miter box. You don’t need anything fancy. Be sure to get a miter box that lets you cut
at 45° both vertically and horizontally. Firmly attach the miter box to your workbench using
hardware or a large clamp.
You’ll always have better- than- average results if you use sharpened, well- made tools. Dull,
bargain- basement tools can’t effectively cut through aluminum or steel stock. Instead of the
tool doing most of the work, you do. That’s no fun, and robotics is supposed to be fun.
Cutting, drilling, and finishing metal are hazardous! Be sure to always wear eye and ear
protection. Don’t disengage the safety device on any tool. Follow all manufacturer instructions.
When using power tools be sure to hold smaller pieces in a vise or clamp while you work with
them. DO NOT ever hold the work with your bare hands!

CUTTING A BASE

Use sheet metal to make robot bases. Mild steel and aluminum are the most common for use
in bots, and they are relatively inexpensive. For both, select a thickness that will support the
size and weight of the robot, but without adding undue weight of its own. Consider the follow-
ing starting points in your design.
For small robots, under 8″:

• Aluminum: 1/32″ to 1/16″ (0.03125″ to 0.0625″)
• Steel: 22–20 gauge

For medium robots, 9″ to 14″:
• Aluminum: 1/16″ to 1/8″ (0.0625″ to 0.125″)
• Steel: 20–18 gauge

For large robots, 14″ and over:
• Aluminum: 1/8″ to 1/4″ (0.125″ to 0.250″)
• Steel: 18–16 gauge

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