Build Your Own Combat Robot

312 Build Your Own Combat Robot
FIGURE 14-4
Front view with arm
up; note the motor
and chain drive for
saws and caster
under pillow boxes.
out of the system and in doing so transmits the maximum amount of torque. These
saws were designed for low speed and high torque. The idea is to pull an opponent
into the “mouth” area of the robot to “chew” on it and send many parts flying.
Chew Toy’s weapons system and armor were constructed from a combination of
surplus catalog goodies and scavenged parts. The prow (the arm) of the robot was
fabricated of steel obtained from a rack-mounted computer system. A 1/4-inch
aluminum plate, part of the support structure for the weapons systems, came out
of a dumpster. Cut into the desired shape with a jigsaw, it was honed with a
Dremel tool and welded to the main support structure (the ammo box).
The weapon support structure fits neatly between the two fan outlets. Attached
to the front part of its underside is an inexpensive small furniture castor. When the
prow is down, that foremost wheel is not visible, but in Figure 14-4 it can be
clearly seen. It’s bolted to the front of the machine and supports the two pillow
boxes that hold the saw bearings.
The bearings used for the weapons system were designed for misalignment—the
bearings are sitting in a rubber gasket, which can move around slightly. This way, we
didn’t have to be precise on alignment. We just stuck the bearings in there, slid the
axle through them, and clamped it down to get a system that is reasonably strong and
spins. The central theme of Chew Toy was building a robot cheaply and easily, and
the KISS (Keep It Simple Stupid) weapons array helped us continue that theme.
The large rod you see mounted to the front of the robot in Figure 14-5 is the saw
axle. The saws are milling tools that we picked up at a metal scrap yard. Berg
sprockets and chains were used to construct the saw’s drive. The shoulder on the
sprocket was cut down with a lathe and the sprocket bolted to the saw, making
one unit. Although combining the saw mechanism in this way made the unit
heavier, it was desirable in this case because of the increased spinning momentum