Design paradigms are the norm in every industry and automated machine tools aren’t any different. Most 3D printers, for example, function in a similar way: each axis rides on rails, with belts pulled by fixed motors. Pen plotters tend to utilize similar kinematics. But sometimes we see builds that ignore established paradigms, like this DIY fixed-belt CNC pen plotter.

Unlike most pen plotters, this machine moves along fixed belts. This layout treats the belts almost like rigid bodies, similar to a rack-and-pinion gear set. Because the belts remain fixed in place, the motors must move. The result is a unique form factor. In this case, creator tuenhidiy made heavy use of PVC pipe for the machine’s structure and enclosures. The materials are very inexpensive, but this machine’s axes ride on hardened steel rods and so it is still capable of drawing very well.

To keep costs down without sacrificing capability, tuenhidiy chose to use an Arduino UNO Rev3 board for control. That reads GRBL G-code files through a microSD card module and controls the stepper motors through a CNC shield with A4988 stepper drivers. There is also a simple Arduino Nano-based controller interface made with a 16×2 character LCD, button, and rotary encoder.

This will work with a variety of different open-source software tools, including popular plugins for Inkscape.