Next, I ran a cable from the
vertical winch rod forward towards
the front support where I pinned it to
the torso plank. It then ran around
two rollers at the front of the prop
and returned to the back of the prop
where it went around a third roller
before returning to the first vertical
winch rod (Figure 8). When the drill
spins clockwise, the cable pulls the
plank backwards at the bottom which
makes the torso lunge forward. As the
torso moves forward, the head is
pulled upwards by the string that
anchors it to the rear plank (Figure 9).
When the drill spins counterclockwise, it pulls the torso board
back to its starting position.
I made two PVC pipe arms and
attached them to two PVC bars that
would be used as the cage bars
(Figure 10). Two block-and-tackle type
pulley systems were used with cables
that went through the arms and
hands. This pulley system decreased
the force needed to open the bars
and decreased the bar travel from
nine inches to four inches (Figure 11).
To control the motor, lights, and
September 2014 91
FIGURE 8. The bottom of the
winch rod that anchors all the
cables and drives their motion.
FIGURE 9. When the
torso board extends, the
string on the top of the
head causes it to lift up
and turn slightly.
FIGURE 10. The two
arms are attached by
the hands to the two
PVC pipe bars.
Top view of
the left arm