by michelle pan
My project is a machine that allows a user to turn a dial to draw a rainbow on any piece of paper! I attached three felt-tipped brush pens to a servo motor using a chopstick, corrugated cardboard, tape, (and a lot of willpower). Their weight is balanced out by three clothespins on the other side of the chopstick, and a solo cup serves as the base of the machine. The movement of the servo is controlled by a potentiometer.
I didn’t start making this with a clear idea of what I was going to build, but as I attached a marker to the servo and looked at the lines it was drawing on paper, I was inspired by the shapes of the arcs to add multiple markers and create rainbows! I’ve especially enjoyed looking at the pieces of paper and the marks left behind on them, whether it was from doing a demo of the machine or from my phases of experimentation. I also find it cool to see the spots where the markers were initially set down on the paper, the little marks left behind when they were adjusted to a different position, and even the splotches when they were left sitting in one location for a longer period of time.
experimentation: at the beginning, i wasn’t sure what i wanted to build, so my first experiment was to see how i could hold up the servo upright in a compact way. i ended up clipping one clothespin around the wire coming out of the servo, and rubber-banding it to another clothespin on the other side to give the servo legs
wiring: i set up the wiring from the potentiometer section of Dr. Sudhu’s Arduino tutorial so i could control the servo using the potentiometer with the Knob program
prototype #1: i attached a pencil to the servo by rubberband-ing it to a clothespin that i clipped to one of the servo horns, but the base wasn’t stable enough to stay standing when it rotated around, even after attaching a counterweight
prototype #2: after a few revisions, i tried providing a heavier base for the machine so that it could support the weight of the pencil/marker as it rotated around
final design: i attached one of the servo horns to a chopstick to enable better attachment of the markers to the servo
final design: to hold the servo upright, i cut a slot into the bottom of a solo cup (a big upgrade from the clothespins)
final design: the markers are taped to a piece of corrugated cardboard, and the chopstick was attached by sliding it through the cardboard
It was a lot of fun to experiment with different materials around my apartment to construct this machine! I had very little experience building and prototyping before this, so it was a challenge to figure out how to physically bring the ideas in my head to life. I learned a lot about how to attach parts together in a sturdy way (tape > rubber bands), and how to help my machine stay upright as the weight distribution changed (large base + counterweights).
If I could do this project again, I would try to incorporate the DC motor as well and make something more complex, since my strengths are more in programming. I still had a good time making this though, and I’m excited to incorporate what I’ve learned into future projects!
Github link to Arduino code
Google Drive link to video
GitHub - loopstick/ArduinoTutorial: Arduino Tutorial
Arduino Tutorial by Sudhu Tewari, potentiometer code borrowed from examples/09_Servo