LEGO Mindstorms Dot Matrix Printer
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LEGO Mindstorms Dot Matrix Printer

Jun 14, 2023

The LEGO construction system is truly an amazing arrangement of plastic, enabling future (and current) engineers and creators to construct everything from castles, to spaceships, or as seen here, a fully working dot matrix printer. After Luke Van In's 7-year-old son asked him to make a press mechanism for a LEGO paper stamping machine, one thing led to another, and after a series of improvements and iterations it somehow morphed into an iPad-controlled LEGO Mindstorms Printer.

The device uses an X/Y table assembly, controlled by a worm gear setup, along with Scotch yokes to translate rotational motion into linear movements. Geometry considerations are accounted for in the software, allowing for consistent spacing in the dot output. When in position, the system pushes a marker down on a small piece of paper, creating images with a 13x13, or 169 pixel resolution.

iPad code for the printer is written in the Swift language using Van In's Swift Mindstorms SDK. This allows the user to load compatible images, then edit them as needed. It pair with the printer's LEGO Mindstorms or Spike Prime hub controller over Bluetooth, moving and pushing down the marker in a programmed sequence. The machine does not sense the marker's starting X/Y position, which can be calibrated via a pen movement dialog in the software.

You can see a quick timelapse demo in the first video below, and a bit of explanation in the second.

Perhaps the beauty of LEGO in that you never really know where a simple idea might take you. It's certainly led a vast number of people to engineering school and other technical pursuits, ultimately inspiring inventions and improvements that will never be fully measured!