Tune in each month for a heads-up on
where to get all of your “robotics
resources” for the best prices!
Fast and Cheap Prototyping
Iway to build a robot — make that
the cheapest ways, too! With
’m often asked about the fastest
prices for everything rising, it makes
sense to look for ways to lower your
robot building costs. Times are tough
right now, after all. One way to pare
down the time and cost of a robot
project is to try out some rapid prototyping techniques. Instead of spending
lots of energy and money on a design
that may not work, try it out first
using quick and cheap construction.
When you’re satisfied your idea has
merit, you can pull out the aluminum
or expensive plastic, and incorporate
any design changes you discovered
during the prototyping phase.
In this month’s column, we’ll
concentrate on just mechanical
hardware prototyping, as this tends to
be an expensive and time-consuming
task for many custom projects. Keep
in mind the resulting bot may not win
any beauty contests and it may not
last long — fast prototypes tend to be
rather delicate. But you won’t have
spent much — if anything! — on
constructing it, and at the end you’ll
know for sure your mechanical design
will work. We’ll detail prototyping for
smaller robots only. Large, heavy-duty
robots need larger and more heavy-duty prototyping methods, which are
beyond the scope of this particular
installment.
Materials Used for
Temporary Signs
For a fast and cheap prototype,
74 SERVO 07.2009
put away the fancy metal and other
“durable” building materials. Even
if you have a scrap of plywood
collecting dust in the garage, pass it
up for stuff that can be cut with a
knife or even a pair of scissors.
Regular readers of this column
will be familiar with such building
materials as cardboard, multi-ply foam
board, and waffle board plastics
often used to make temporary signs.
Depending on the application, these
may be used in prototypes or finished
designs, though the thinner and
lighter materials find their best use for
testing out ideas on temporary robots.
To recap: Heavy-duty cardboard is
available in thicknesses from 1/8” to
over 1/2”. You can find it in larger
sheets or simply cut up a used box.
Laminate several pieces of cardboard
to make it thicker and more stiff.
“Criss-cross” the corrugation of the
inner layers of the cardboard for
greater strength. Use a good paper
glue or contact cement for a solid
bond. Cut with a sharp knife (be
careful of your fingers!) or any small
fine-toothed saw.
The strongest cardboards use a
honeycomb-like inner layer. You
can often find this type in packing
materials for very heavy objects, such
as automobile engines. Use a hand or
power saw; it’s too thick to be safely
cut with a knife.
Foam board sandwiches a piece
of 2-6 mm foam inside thin sheets of
paper or plastic (paper lamination is
far more common). Often used in
craft and school projects, you can find
foam board in colors at any art or
craft supply store. Colored boards are
more expensive, plus you really only
need white. Cut with a knife or small
hobby saw.
Corrugated plastic is a common
staple in the sign-making biz. It’s used
for temporary outdoor signage,
restaurant menu boards, that sort of
thing. The plastic is composed of several layers, all bonded together during
manufacture. To give the material its
strength, the inner core is corrugated
like cardboard. The outsides are
smooth and made with very thin ply
layers. Corrugated plastic comes in
many colors but you can usually paint
it, and several sheets can be cemented
together for extra durability. A
common brand is Gatorboard, but it’s
available under many different names.
The idea with all of these materials is that they are easy to cut and
drill. In most cases, ordinary hand
tools are all you need. Holes can be
drilled with a hand drill, making these
materials better suited for robot
projects involving young learners. Of
course, give them pieces already cut
to size, to avoid having them handle a
sharp knife.
When cutting cardboard, foam
board, or corrugated plastic, bear in
mind that small pieces are inherently
more stiff than larger ones. A 2 x 4
foot sheet of corrugated plastic looks
awfully flimsy when you hold it up,
but cut it down to the sizes you’ll
most often use — four to eight inch
round or square “body part” pieces —
and you’ll find the material is remark-
