Our hero [Alex] just built a sidewalk graffiti machine, and it’s a beauty to behold, so make sure you check out the video below the break. But don’t neglect [Alex]’s blog, and the build videos throughout. (Nice t-shirt in the wheel-making video, BTW.)
The machine itself is basically a two-meter wide printer where the roller is replaced with drive wheels. The frame, made of plywood, looks great and helps keep the machine light weight. Everything is done with DC motors and timing belts, which means motor encoders and closed-loop control in the firmware. It connects via a WiFi serial bridge, made with an ESP8266, to [Alex]’s cell phone.
Everything, from plans to software, is available on [Alex]’s GitHub for the project.
Watching the video, it occurred to us that this printer doesn’t have to limit itself to printing rasters like the Chalkjet or the txtBomber, but instead can do actual vector artwork — smooth curves and all. It’s going to be tricky getting the 2D motion planning to work, and it’ll have to be tuned to the chalk-flow from the spray can, but being able to mimic the fluid lines of a real spray painter will be worth it. And if we’re lucky, the smoother motions will help sort out the PID control’s quirks as well.