The Agnewgraph I can turn out a pretty nice Spirograph drawing. Instead of relying on meticulously acurate CNC hardware, it uses a Spirograph stencil similiar to that business card we’re so fond of. The key to the [Mpark's] design is an analog joystick which is attached to the pen. As the pen follows the plastic guide around, a Propeller microcontroller calculates the angle of travel based on that joystick. These measurements are used to decide how to move the two stepper motors that provide horizontal and vertical motion to the frame. We’ve attached a video after the break just in case our rough description didn’t do it for you.
