My first drawing machine was built for a class in the HCII called Gadgets, Sensors & Activity Recognition, taught by Scott Hudson. It's a simple machine that draws by spinning two geared wheels, and changing the length of beaded chain which supports the pen. The machine is driven by an Arduino Uno with a motor-shield, and uses an interface in Processing to collect user input and process images.
The machine is made from a number of materials including plywood, acrylic, and ABS plastic and is the product of various digital fabrication techniques including 3D printing, laser cutting, and CNC machining.
Numerous iterations of each component were made to test their compatability with the off the shelf components used in the project and to further develop their design.
Anatomy of the machine
HOW IT WORKS
By drawing many small arcs along another arc generated from the other center point, density is created in the image. Variation in this density reads as lightness or darkness in the final picture.
When drawing, one wheel acts as the center point of a radius while the other moves the pen along that radius. By knowing how many steps the motor has and how much the drive chain moves with each step, I was able to effectively set the radius needed and move the pen to the desired point on the radius.