FIGURE 2. Layout pattern for cutting and drilling the bottom
deck of the ArdBot. The only truly critical dimensions are the
cutouts for the wheels and the placement of the two sets of holes
immediately beside the wheel cutouts. These holes are for the
servo mounts. See Figure 5 for a description of all holes.
yourself or, if you choose, purchase them separately.
If you make the mounts, be aware that sizing is
critical. The two holes on either side of the mount
must be spaced 3” apart to accommodate the same
hole spacing in the bottom deck.
The base parts may be cut from stock measuring 12”
x 12” which is a common size for expanded PVC or other
plastic purchased through mail order. A motorized scroll
saw is the perfect tool for cutting out the ArdBot base
components, but if you don’t have one handy, a coping
saw also works. Use a wood blade; it’ll work whether
you’re making the base with aircraft-grade plywood
(available at the hobby store), PVC, or other plastic.
If using foam board or picture mat, you can cut the
pieces using a sharp hobby knife or mat cutter. The usual
safety precautions apply. A circle cutting jig makes perfect
Table 3. Electronic Parts.
Arduino Uno (or compatible) microcontroller
board with USB programming cable.
Mini solderless breadboard; 170 tie points.
Set of solderless breadboard wire jumpers
(or make your own using 22 gauge solid
AA x four battery holder, with female header
connector; see text.
Nine volt battery clip, with 2.1 mm polarized
barrel plug; see text.
Length of 12 (or more) breakaway 0.100” male
header pins, double-sided (long) pins; see text.
54 SERVO 12.2010
top deck of
are the four
holes in the
circles when using these materials. If you don’t own a
circular jig yourself, see if the local picture frame store will
make the cuts for you. When using picture mat material,
cut two of everything, and double-up the pieces for extra
stiffness. Except for the large center hole in the top deck,
all holes are drilled with a 9/64” bit.
Assembling the ArdBot
With the body pieces constructed (or purchased) and
all other parts in hand, you’re ready to build your ArdBot.
Before assembly, you may want to use 150 grit
sandpaper to smooth the edges of the base parts. Orient
the bottom deck so that the holes are aligned as shown in
Figure 5. Note that the holes for each servo are not
symmetrically placed on the deck. This is to accommodate
Table 4. Power.
AA alkaline or nickel metal hybride
Nine volt battery.
Optional (but nice to have) Parts.
1 Nine volt metal or plastic battery holder.
Hook-and-loop (Velcro) strips for mounting
battery holders and solderless breadboard;
small pieces of double-sided foam tape.