Wallrus is a graffiti plotter built in Olin College’s Fall 2007 Principles of Engineering course. It can paint arbitrary paths from SVG images onto vertical surfaces up to eight feet square. Sadly, it has almost nothing to do with the majestic marine mammal its name is based on.
Here’s a video of Wallrus painting a vertical line. Two stepper motors lie at the top corners of the painting surface, supported by wooden towers. A pulley connected to a toothed belt is attached to the shaft of each motor. A carriage containing a spray can and electronic actuator hangs from the two belts. By controlling the position of the motors, we can move the spray can almost anywhere on the painting surface. Combining this with electronic actuation of the spray can allows us to paint whichever lines and curves we desire.
You can learn more about the design of the system via the links above. We’ll upload more videos as we finish tweaking the system.