Build Your Own Combat Robot

74 Build Your Own Combat Robot
FIGURE 4-6
24-volt,
3.9-horsepower
electric motor.
(courtesy of Carlo
Bertocchini)
Motor Sources
You can acquire electric motors in two ways: you can purchase them from a motor
manufacturer or retail store, or you can salvage them from other pieces of equipment.
Many robot builders use salvaged motors because they usually cost less
than 20 percent of the original cost of buying a brand new motor. Appendix B in
this book lists sources for obtaining robot motors.
Robotics companies are starting to sell motors that are specifically designed for
combat robots. For example the 3.9-horsepower Magmotor sold by http://
www.RobotBooks.com has become the standard motor used in several champion
BattleBots. Figure 4-6 shows a photograph of the motor.
Because electric motors are so common, they can be found easily. Some of the
best places to get good electric motors are from electric bicycles, electric scooters
and mopeds, electric children’s cars where the kids ride and drive, electric model
cars and planes, trolling motors, windshield wiper motors, power window motors,
power door locks, and even powered automobile seat motors can be used.
Some people have even used automotive and motorcycle starter motors and electric
winches from the front of a pickup truck or from a boat trailer.
Probably the two best places to get electric motors are from electric wheelchairs
and high-powered cordless drill/drivers. The advantages to the electric
wheelchair motors are that they already come with a high-quality gearbox, and
the output shaft has a good set of support bearings. Depending on which type of
motor you get, you could directly attach the wheels of the robot to the output
shaft of these motors. Several companies sell refurbished wheelchair motors. One
of the best places to get these motors is from National Power Chair (http:// www.
npcinc.com). Figure 4-7 shows a wheelchair motor.