Page 43 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

24 Making Things Move

horizontal, it is rotating about the X FIGURE 1-25 Rotations on an airplane are given
axis, called roll. When then nose dips specific names.
up or down, it’s rotating about the Y
axis, called pitch. And when it rotates
around the Z axis to go into a turn,
it’s called yaw. Remembering the
names of these three rotations isn’t
important. Just keep in mind that all
movement is a combination of three
translations and three rotations.
Before we move on, I want to
introduce two more simple terms
used to describe motion:

1. Axial refers to along an axis.
Axial rotation is around an
axis (either clockwise or
FIGURE 1-26 Axial and radial motion and forces
counterclockwise). Axial load
or force is applied parallel to
an axis.

2. Radial refers to perpendicular
to an axis. A radial load or
force is applied perpendicular
to an axis.

Figure 1-26 illustrates these concepts.

Minimum Constraint Design

Have you ever sat at a table that wobbled every time you rested your elbow on it?
Most of us have, and we’ve also probably tried to stop the wobble by putting some