ARMOR and CHASSIS
Arguably, the most important aspect of a ComBot is
the armor that protects it from the attacking opponents.
Next in line will be the chassis that holds everything
together. For most applications, steel or aluminum will
offer the best combination of affordability, durability, and
weight. Bots with heavier active weapons like hammers or
large saw blades may want to conserve weight by using
aluminum, where bots with weight to spare may opt for
Bot Tip: Always aim to have the lowest center of
gravity possible. This way, the Combot will be harder to
invert and easier to control.
Speed controllers are about as close to a brain as
you’ll find in a
purpose of a speed
controller is to
from the receiver,
and turn those
signals into voltage
to your motors.
We’ll need one
per motor for this
tutorial, we’ll use an
IFI Victor 883 speed
IMPORTANT: For this application of the IFI Victor 883
speed controller, we’ll need signal boosting cables rather
than the ones that are included. Signal boosting cables are
generally available as an accessory and are used to
amplify the signal sent from the receiver. This allows the
speed controllers to have more accuracy. The 883 has
three connections (not including the fan): the battery
input; receiver input; and motor output.
IFI Victor 883 speed controller.
Bot Tip: You’ll want to triple-check that your wiring is
perfect before putting any power through your speed
controller. If the unit short circuits or the battery polarity
is reversed, the controller will be destroyed.
Picking the right motor for your ComBot is essential. If
you choose a motor with too little torque, your bot won’t
move. If you choose a motor with too much torque, it will
tear your robot
apart the first
time you run it.
We’ll be using
This will give
us plenty of Magnum 775 planetary gearmotor.
torque to work with while maintaining a light weight and
relatively low battery consumption. You’ll need two drive
motors, and may want to consider buying a third motor
for an active weapon. For beginning ComBot builders, it’s
easiest to start small by creating a wedge bot with no
Bot Tip: Indirect drive (using gears, chains, or belts to
connect your motors to your wheels) is an excellent
method for protecting your motor shafts from heavy
impacts that could potentially ruin your motors. For the
sake of simplicity, we won’t cover specifics of creating
an indirect drive system, but if you are mechanically
inclined, it’s a highly favorable option!
WHEELS and HUBS
right wheels for
your robot can
opponent into the
arena walls at full
speed or spinning
out when you take
a sharp turn.
Colson wheels are a great mix of traction, low friction,
light weight, and durability. Depending on the diameter of
wheel you select, you may have a different shaft size. In
most cases when working with Colson wheels, you’re best
off just buying a hub and drilling directly into the side of
the wheels to connect them.
Colson 4x1 and a quarter wheel.
BotTip: Protect your wheels! Plan to have your
wheels inside the body of your bot so that the only
visible parts of the wheels are the parts touching the
ground to move the robot.
RADIO CONTROL TRANSMITTER
The transmitter is
the device that sends
the radio signal telling
your ComBot what to
do. For our ComBot,
we’ll be using a
Spektrum DX6i six-channel 2. 4 GHz
radio system mode 2.
This will give us
plenty of channels to
work with for drive
motors and weapons,
while eliminating all
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