Just when you thought you’ve seen it all…
If you’ve ever been to a Maker Faire, then chances are you’ve stumbled upon the PancakeBot, a CNC machine that extrudes delicious art out of batter. A few years ago, RIT Assistant Professor Ted Kinsman decided that he wanted to print using something other than ink as well. His choice? Coffee, or any other material with low viscosity.
The machine itself is an xy-axis printer equipped with a solenoid liquid valve, stepper motors for positioning and an Arduino, which can store images of approximately 80×100 pixels. However, despite its mediocre resolution, it does plot human faces fairly well. The drip size, the nozzle distance and the paper that the beads of coffee extract fall onto can all be changed.
“For many years I have thought about building a machine that could paint for me,” he explains. “Since I always have leftover coffee, I thought it would be a fun medium to play with.”
For what it lacks in resolution, it surely makes up for in cost — Kinsman says that it’s super inexpensive to create images. To begin, the professor snaps a picture, heightens the contrast and converts that into a PGM file that the Arduino could read. The sketch then prints a test grid, which can be modified by dropping in a PGM image and adjusting the space between drops. As MAKE: notes, the grayscale is converted to an array of dots whose darkness corresponds to the length of time that the valve of the pipette opens to release a coffee drop.
“Each of the pixels is turned into a number from 0 (no coffee) to 256 (the largest drip size). The size of each pixel is controlled by determining how long to open the drip valve for — the largest drop (and darkest pixel) requires the valve to be open for 63 milliseconds. In this way, the machine currently can do 53 different shades of coffee,” according to PetaPixel.
A Mariotte’s siphon is employed to ensure that the depth of the coffee in the reservoir won’t affect the pressure, which in turn could influence the size of the drops. Each print requires about an hour from start to finish, but takes roughly a day to fully dry.
Looking ahead, Kinsman would like to explore the possibility of adding another stepper motor so that he can make spirographs or use a syringe that would enable him to print with thicker liquids. But until then, you can watch it in action below (note that the machine is using blue ink) and read more about the project here.