So, this is how an inkjet printer works:
There are two motors, one to move the paper(the Feed motor), and one to move the print heads(the Head motor). The feed motor pushes the paper forward a line, and then the head motor sweeps the heads across that line, and the print heads(the ink cartriges) spit out whatever color the computer tells them is appropriate at that point on the page. That's the basics. Got it? Good. On to the interesting stuff

I was painting a mural the other day, and finding it mind-numbing. Mostly because it wasn't my original artwork-there's that I like that I was putting up on my wall as a mural. With illustrations, it's fourteen pages long, and around page 5, my hand started to cramp and I started to think of things I could do instead of painting. I realized that I could take the feed motor out of an inkjet printer, and instead use the signals the printer sends to the motor to move the entire printer forwards, instead of the paper. Then, the printer would print on whatever surface you put it on.

I scoured reuse and craigslist for old inkjet printers (MIT only throws away old laser printers now--a sign of the times, I guess). A kind soul donated an old Lexmark Z32 printer to a worthy cause. I grabbed a screwdriver and started gutting it.

Most of an inkjet printed is made of plastic. There's a small control board, two motors and gear assemblies, a rack for the cartridges, and then a lot of plastic to hold the paper and make it look pretty. I'm sure some of the fancier printers are a lot more complicated, but I was dealing with the barest-bones of all inkjets. Inside the printer, the control board, head motor, and cartridge rack were all conveniently mounted on the same piece of sheet metal, so I pulled that out, unplugging the connection for the feed motor, which was lived nearby. Both motors were bipolar steppers. I needed a good way to make the printer move forward steadily, without shaking too much, so I hacked up an old scanner carcass that was lying around miters, replaced the scanner's unipolar motor with the printer's bipolar feed motor, and bolted the printing assembly onto the scanner carriage that normally carries the fluorescent light and imager.