PARTS LIST
ARMOR & CHASSIS: Metal for the armor and
chassis is most easily purchased locally, however, it
can be purchased from numerous websites including
www.metalsdepot.com/products/hrsteel2.phtml?
page=sheet&LimAcc=$LimAcc.
SPEED CONTROLLERS: The IFI Victor 883 speed
controller can be purchased at www.robot
marketplace.com/products/IFI-V883.html. NOTE:
Remember to purchase the PWN booster cable AND
the 24V fan (they're options in the drop-down menu).
MOTORS: The Magnum 775 Planetary Gearmotor
can be purchased at www.robotmarketplace.com/
products/ RP-MAGNUM775.html.
WHEELS & HUBS: A selection of Colson wheels can
be found at www.robotmarketplace.com/products/
colson_wheels.html Hubs can be found at www.robot
marketplace.com/products/hubs.html Note: The
Magnum 775 Planetary Gearmotor has a . 50" shaft,
meaning you’ll need hubs with a . 50" bore.
BATTERIES: The 18V 3.0 Ah NiCad BattlePack can
be purchased at www.robotmarketplace.com/products
/ BPK-3000-18.html.
RADIO CONTROL TRANSMITTER & RECEIVER: The
Spektrum DX6i six-channel 2. 4 GHz Radio System
Mode 2 can be purchased, along with the BR6000 Bot
Receiver at www.robotmarketplace.com/products/
0-SPM6600.html. The battery needed for the receiver can
be purchased at www.robotmarketplace.com/
products/ 0-SPM9520.html.
FUSE: A 60 amp fuse, along with a fuse holder, can
be purchased at a local electronics store, or online at
www.radioshack.com/product/index.jsp?productId=
2102777&filterName=Category and
www.radioshack.com/product/index.jsp?productId=
2062255&filterName=Category, respectively.
LED INDICATOR LIGHT & RESISTOR: An LED
indicator light and appropriate resistor can be purchased
at a local electronics store, or online at www.radio
shack.com/product/index.jsp?productId=2062549&
filterName=Category and www.radioshack.com/
product/index.jsp?productId=2062324, respectively.
NOTE: When purchasing your LED and resistor, ask your
vendor to double-check their compatibility, both with the
18V battery we'll be using and each other. Otherwise,
you may blow out your LED.
MASTER POWER SWITCH: You can purchase a
master power switch to your liking at your local
electronics store, or find a nice selection at www.robot
marketplace.com/products/power_switches.html.
WIRES: 12-gauge wire can be purchased locally,
or online at www.robotmarketplace.com/products/
wire_and_accessories.html.
WIRES
While they may seem somewhat innocuous, it is
important to give special attention to the wiring of our
ComBot. We need to
ensure we use a low
enough gauge that
the wires can stand
up to the amp-flow
of the batteries, but a
high enough gauge
that the wires are
manageable. It’s also
important to make
sure that the bot is
wired in a way that
there is a bit of slack
so that during heavy
impacts, the wires
don’t break loose. For our build, we’ll use 12 gauge wire
which can be picked up at any local electronics store.
Wire.
CHASSIS DESIGN
Before buying parts for a ComBot, it’s important to
have a design in mind. While you may not have the latest
and greatest 3D design software, there’s very little that
you can’t do with just a pen and paper. Sketch out the
shape of the robot first. Is it a wedge? Where does the
weapon come out of the chassis? Where do the motors
go? How will the motors connect to the weapon and drive
wheels? Always remember, KISS (Keep It Simple, Stupid!).
The most successful ComBots are often the simplest, and
it’s very important to keep your first design clean and easy
to build. For the sake of simplicity, let’s keep this first
design to a quadrilateral footprint.
In designing the ComBot, keep in mind that arcs and
triangles are the strongest and second strongest shapes,
respectively. That means that the design of the bot should
incorporate those structures, especially at points of heavy
impact. Again — to keep things simple — it’s advisable to
avoid arcs in the design unless you have easy access to
machinery capable of producing such shapes.
The simple reality of ComBots is that the competing
robots get beaten up during every match, and good robot
designs should be easy compartmentalized so that instead
of replacing an entire robot every time it takes a hit, only
the portion that is damaged will need replacing. For this
reason, it’s extremely helpful to keep the chassis and
armor as separate beings. In other words, we could spend
eight hours milling out the perfect unibody chassis, but
after it takes its first hit, it’ll get bent out of shape,
meaning another eight hours of milling. Instead, plan to
Bot Tip: Google SketchUp is a great, free tool to
create a quick and dirty chassis design with.
Bot Tip: If your local metal works doesn’t have the
metal you need for your chassis, they’re sure to know
someone who does- so don’t hesitate to ask!
SERVO 04.2010 71
