Build Your Own Combat Robot

FIGURE 14-5
Front view with arm
down showing
2-by-4 and nails.
Chapter 14: Real-Life Robots: Lessons from Veteran Builders 313
it offers. The design allows Chew Toy’s saws to strike an opponent and keep on
spinning and doing damage instead of stopping abruptly.
The motors that power the saws are mounted on a support structure welded to
the front of the robot. The saw motors also run on 24 volts instead of the recommended
12. When in battle, these motors get only intermittent use; thus, the reduction
in life span from this hard usage should not pose a problem. If one motor
should blow out during a competition, the second one will be able to power the
saws. These motors were found through a surplus supply catalog. Although I had
no specs on their design, and I knew nothing about who made them, they were inexpensive
and testing proved they had the necessary torque and would work well
for their intended purpose.
The arm was originally intended to right the robot if it were turned on its back,
but then it became a weapon in its own right. The arm is made out of angle iron
bought from a local hardware store. Welded onto the ammo box and attached to
the front is a little bent piece of steel with a hook.
The initial welding on Chew Toy was farmed out, and one of my teammates
who had welding equipment (and skill at using it) did later welds. The original
arm conception has evolved considerably, and the appearance changed as we continued
our improvisation. Things were added as the inspiration hit us. The old
motherboard and perforated metal screening were attached as armor. The 2-by-4
with nails was incorporated to make sure the robot could right itself should it be
flipped. The nails, and the reach they added, were necessary to accomplish the
flipping. When the arm is lowered (Figure 14-5), the nailed 2-by-4 gives the robot
additional protection. More of the armor in the form of circuit boards, perforated
metal, and another 2-by-4 to protect the robot’s rear was added when construction
was nearing completion.