Page 144 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

124 Making Things Move

The most important component of any moving system is an actuator, which is the
thing that causes a mechanical system to move. Motors are the most common
actuators, and as you’ll learn in this chapter, there are many different kinds to choose
from for your projects. We’ll also cover a few other ways to create motion.

In previous chapters, you learned about force, torque, and power, so by now you have
the tools to determine how strong your actuator must be for a specific task. We’ll use
that information, along with other project-specific requirements, to help us narrow
down the available options. This chapter covers a lot of information, so take it slow
and don’t expect to understand everything on the first pass. Now that you’ve been
warned, let’s talk a bit about how motors work.

How Motors Work
Motors turn electrical energy into mechanical energy using coiled-up wires and
magnets. When electricity flows through a wire, it creates a magnetic field around it.
When you bring a permanent magnet close to that magnetic field, it will be repelled
or attracted.

Motors take advantage of this magnetic field by mounting coils of wire on a shaft, so
when the magnet repels the coils, the shaft begins to spin. In order to keep the shaft
spinning, you need to keep flipping the magnetic field so the series of repel, attract,
repel, and so on continues and the shaft keeps spinning. Different motors do this in
different ways.

P roject 6-1: DIY Motor with Magnet Wire

Let’s make a simple motor to better understand how it generates mechanical energy. 1

Shopping List:

• 10 ft length of magnet wire (RadioShack 278-1345; use the green spool)
• Ceramic disk magnet or other strong magnet (McMaster 5857K15)
• Two big paperclips

• Large eraser, piece of clay, or block of stiff foam