First Night Austin street celebration.
Thinking this the ideal venue for such
an amalgam of retro art techno
geekdom, I spoke with a few of my
regular cohorts at The Robot Group
and decided to propose “Robo
SpinArt” for First Night. Since I’d
already been thinking about making a
spin art machine of some type, I
sketched up some plans and features
(Figure 1) and sent in a proposal.
After weeks of waiting for an
answer, I just decided to go ahead and
start on the machine myself. I figured
if First Night did say yes, I would need
to have a good head start to ensure
the unit would be ready by New
Year’s Eve. If they didn’t approve the
proposal, at least I would be on my
way to having a cool new project.
MAKING A LIST ...
CHECKING IT TWICE ...
Using the notes from my sketches,
I outlined the functions of the machine.
I started by going over the things the
original old style spin art machine had
and compiling a list of the things I
needed to do to “update” the machine
for the “Joystick Generation.”
• Limit the ammo: One of the first
things to do to improve the machine
would be to limit the amount of paint
available (i.e., 30 drops or shots of
paint). By making sure the kids only
had a limited amount of paint ammo,
I could eliminate paper saturation as a
problem and have a much better
chance of the finished piece having
that classic spin art look. Not only
would this reduce the chance of
someone making a mess of their
paper, it would also cut down on the
amount of paint consumed by the
device in the course of its operation,
thereby keeping operating costs
down. This approach had the added
advantage of reducing the amount of
time kids had to wait to use the
machine since once your ammo was
gone, your turn was over.
• Limit the time: By putting a countdown timer on the machine, a sense
of urgency is created. If you only have,
say 30 seconds, you need to start
painting quickly. This not only makes it
exciting, it helps with the throughput
of the machine. Kids who carefully
place their shots would know exactly
how much time they have to aim and
fire their paint. I could also use this as
a way to calculate the maximum
throughput when trying to determine
how many kids could be served and
how much paper should be brought
to a given event.
• Arcade style controls: The paint
firing would be controlled by a series
of arcade quality buttons that could
be used to fire the paint shots. An
arcade style joystick would be used to
aim where the paint would fall. Not
only would arcade-style controls make
the machine more robust, they would
also be familiar to the kids and give
them an intuitive interface to operate
the machine. Each of the buttons also
had a colored cover that would light
up to indicate the pump was on and
what color of paint would dispense
when a given button was pressed. A
paint gantry (reminiscent of a record
player tonearm) would move in an arc
over the bucket to allow the kids to
aim at different parts of the paper.
• Speed control: As a new twist on the
old spin art design, I thought that
since I had both UP/DOWN and
LEFT/RIGHT controls in the joystick, I
could use the UP/DOWN motion to
control the speed of the motor that
spins the paper. Pushing UP on the
joystick would accelerate the paper
causing the paint tendrils to become
thinner and the colors could become
more translucent. Pushing DOWN
would make the tendrils appear to be
thicker and the colors more vibrant
since less paint would be thrown off
the paper. Also, accelerating and
decelerating the motor right as you
drop a paint shot could alter the paint
trajectory as it moved outward on the
paper. This would cause effects such
as swirling or bending paint tendrils.
Having this sort of hidden functionality was reminiscent of special combo
moves in video games.
• Freeze frame: Another common
PERSONAL ROBOTICS
problem with the older spin art
machines was the inability to see your
artwork until the motor stopped
spinning the paper. By the time the
motor had stopped, it was too late to
add paint to a blank portion of the
paper or add a few more paint drops
that might improve the final piece. To
allow the kids to preview their work, I
planned to add high-intensity white
LEDs pointed down into the bucket to
act as strobe lights. These lights would
be timed by an encoder on the motor
shaft that, when activated, would blink
the LEDs one time per rotation of the
paper. This would freeze the image
and let the progress of the painting be
inspected while it was being made.
• Video broadcast: As an added
touch, I thought it might be interesting
to have a video camera in the top of
the machine pointing down into the
bucket so people in line could watch
as the spin art was being made. This
would also help them understand the
operation of the machine, reducing
the amount of instruction required
when it was their turn.
• Card logo and inscriptions: When I
was a boy, it was a standing rule in my
household that when we attended an
event and the event offered souvenirs,
we were only allowed to choose one
that had the event or location written
on it. As it was likely that the spin art
machine would be taken to various
events, I thought it would be neat if
I could continue this tradition by
inscribing text and placing a graphic
logo on each card. By limiting the
travel of the paint gantry, I could
protect the center of the card from
being painted, thereby leaving space
for this inscription. It would then be a
simple matter to pre-print cards for an
event with a logo and some descriptive text. However, there was always
the problem of printing too few or too
many cards for a given event (leading
to wasted cards). To mitigate this, I
planned to print some cards with a
generic graphical logo (i.e., a birthday
cake), and then add text to the logo at
the time of painting (i.e., “Happy
Birthday Sami!”). This would make
creating custom cards easy and
January 2008 71
