Page 231 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

Chapter 7 Bearings, Couplers, Gears, Screws, and Springs 209

diameter that fits the motor and shaft you want to join, all you need to do is cut a
short piece of it, and then push your motor shaft into one side and the shaft you want
to connect into the other. If you want a tighter fit, you can put small hose clamps (like
2
McMaster 5388K14) on each end of the tube to secure your coupler. Search for
“tubing” on McMaster for a dizzying array of options in every material and dimension
you can think of.

For flexible coupling of two shafts
FIGURE 7-23 U-joints (credit: ServoCity)
in different planes, you need to
use a universal joint (U-joint) (see
Figure 7-23). These come in many
different sizes and shapes, and sweep
through a variety of angles. They can
also be used to join shafts of different
sizes. Many other flexible coupling
options are available. Just search for
flexible shaft couplings on McMaster
(or any other components supplier
website), and you’ll find a wide array of options with funny names like spider, Oldham,
and bellows couplings that accommodate different kinds of misalignment.

Attaching Gears and Other Components to Shafts
The options for attaching components to shafts are basically the same as for attaching
components to a motor shaft, with a few additions:

• Press it It’s easier to press fit components at the ends of shafts. If you need
to locate a component in the middle of a shaft, this is probably not the way
to go.
• Glue it If your component will slide onto the shaft, you can try using a
strong super glue or epoxy to hold it on. If both components are wood, wood
glue is a good choice.
• Pin it If your component is wide enough to drill a small hole through its side
or hub, you can match drill the component and shaft, and use a nail or dowel
pin (wooden or metal) to hold them together (see Figure 7-24, left and middle
images). Match drilling refers to lining up two things and drilling through
them both at once to make sure they are perfectly aligned.