CHAPTER 20 ■ COUPLERChoosing Between Brass and Aluminum Tubing
You can make the couplers out of either brass or aluminum (see Figure 20-2). Brass is three times heavier,
about 6 grams for each coupler. Brass is stronger than aluminum, and thus is more likely to retain its shape
during metal-working. Most importantly, brass is the easiest to machine. For this reason, I recommend
working with brass for your first attempt at making the couplers.
Aluminum’s light weight is a definite advantage for competition robots. Even though it is a softer metal,
it is unlikely to break, as the forces exerted on it are trivial on small robot sizes.
Specifying and Obtaining Tubing Sizes
Both brass and aluminum tubing are available in display cases at most hardware stores (see Figure 20-3).
For this project, you’ll need a total of four tubes; one each of diameters^3 / 16 inch,^7 / 32 inch,^1 / 4 inch, and
(^9) /
32 inch.
Figure 20-2. Two brass couplers (left) and two aluminum couplers (middle) made with tubing. Two plastic
couplers (right) made on a lathe or milling machine out of solid rod