Servo - December 2010

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.

Qty Description

1

Arduino Uno (or compatible) microcontroller board with USB programming cable.

1

Mini solderless breadboard; 170 tie points.

Set of solderless breadboard wire jumpers (or make your own using 22 gauge solid conductor wire).

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

FIGURE 3.

Layout pattern for cutting and drilling the top deck of the ArdBot. Critical holes are the four small ones nearest the center. These must match the four servo mounting holes in the bottom deck.

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. Here’s how.

Step 0

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