Page 132 - Robot Builder's Bonanza

MAKING THE BASE 101

Table 10-1 PlastoBot Parts List

1 4″ 4″ 1/8″-thick plastic*
2 Pololu micro gear motors, 100:1 gear ratio, item 992†
1 Pololu mini motor brackets (pair), item 989†
1 Pololu wheels with rubber tires (pair), 32mm diameter, item 1087†
1 Pololu ball caster, 1/2″ ball, item 952†
Misc. Assembly hardware for these parts comes with the parts; if you substitute, you may
need an assortment of 2-56 or 4-40 1/2″ machine screws and nuts.

* Use expanded PVC, ABS, polycarbonate, acrylic, or most any other plastic. Acrylic and polycarbonate may be found at
better- stocked home improvement stores; PVC and ABS plastic is available at specialty plastic outlets and online.
† Motors, motor mounts, wheels, and ball caster are available at Pololu.com, and many of its distributors. You may also use
most any other miniature motors and wheels if you have another source for them. The motors are approximately 5/8″
square by 1″ long. The wheels are 32mm (about 1-1/4″) in diameter.

While the plans call for 1/8″ plastic, you may use another thickness if that’s what you have.
For reasons of weight, you’ll want to avoid using a dense plastic (acrylic or polycarbonate) if
it’s over 3/16″ or so. The thicker plastic is also harder to cut and drill.
Begin with a 4″ by 4″ square, and lop off the corners. How much material you remove is
up to you, but a 1/2″ chamfer is sufficient— to measure this amount, just make a set of marks
1/2″ from each corner, and cut a 45° diagonal across the marks.
The PlastoBot design calls for rectangular cutouts for the wheels— what I refer to as wheel
wells. For the wheels specified (see Table 10-1), the cutouts measure 1-3/8″ by 1/2″; both

Figure 10-1 The finished
PlastoBot, using two micro motors,
wheels, and a small plastic ball caster
for balance. The robot measures
4″ square.

10-chapter-10.indd 101 4/21/11 11:45 AM