CHAPTER 20 ■ COUPLER
The tube walls must be 0.014-inch thick. “Wall size” is the thickness of the metal.
K&S Engineering manufactures the specific tubing on my couplers, stock numbers #129, #130, #131,
and #132. The tubes average around $2.00 each. You can purchase similar tubing online at McMaster-Carr,
Online Metals, or MSC Industrial Supply.
One pair of couplers requires only 5 cm of length, but the tubes come in lengths of 12 inches. Plenty
remains left over for other robot projects or additional couplers.
If you don’t have access to these diameters of tubing, you’ll see how the sizes were determined in a
moment. That way you can choose appropriate tubing based on what is available to you.
Telescoping Tubing Required
With the diameter and wall thickness specified, each tube fits neatly inside the next larger size (see Figure 20-4).
This is called telescoping tubing. At the store, try sliding one tube into the other to make sure they fit snugly.
Figure 20-3. Hardware store display case of brass, aluminum, and copper in the shape of tubes, angles,
channels, strips, and sheets