Kinetic Art Arm

This is the first 'robot' that I ever worked on. I'm using the term robot pretty loosely here because this robot was really just an electromechanical arm that could be controlled by hooking up batteries to the motor. In 1987 I was in high school and was taking an art class. This was a pretty free-form art class so we were able to choose to work on whatever we wanted. In that class I did drawings, paintings, copper etchings, and at one point I convinced my teacher to let me make a robot arm. He wasn't terribly thrilled about that one since it was barely art. I knew little to nothing about torque, gear ratios, or the power that a motor could deliver so in retrospect, I'm suprised that I was able to get it to do anything. I built it out of a piece of aluminum square tubing and a gearmotor that I bought from Edmund Scientific. At the end of the arm was a ping pong ball or something spherical. The arm had a single degree of freedom at its base that let it rotate from a horizontal to a vertical position. I painted everything with acrylic paint to make it more acceptable as art. My teacher wasn't pleased. He gave me a deadline and told me that it had to at least be able to move the arm for me to get a passing grade. Somehow I managed to get it to just barely work and probably got a C on that 'artwork'.