Solder joints on PCBs don’t usually require extra protection, but loose wires are a different story. Because they can move around and touch each other or the enclosure, you need to protect the bare wire from shorts. Most people use either electrical tape or heat shrink tubing for the job. But cutting heat shrink tubing to length can be a time-consuming process if you have many wires to protect. That’s why Mr Innovative used an Arduino to build this handy machine that cuts heat shrink tubing automatically.

Mr Innovative built similar machines in the past, including one that feeds four different wire spools and cuts them to desired lengths. This machine is similar, but works with a single spool of heat shrink tubing. The user inserts one end of the tubing into the machine, sets the length via a touchscreen interface, and the machine takes care of the rest. It will continue to snip off sections of tubing, all of the same length, until it runs out of heat shrink to work with. 

An Arduino Nano board controls the machine through a custom PCB that contains two A4988 stepper motor drivers. A NEMA 17 stepper motors drives a wheel that feeds the heat shrink tubing. A high-torque stepper motor in a servo motor package actuates a linkage that pushes the cutting blade. The display is a Nextion NX3224K028 2.8″ resistive touchscreen with a resolution of 320×240, which has a custom interface programmed by Mr Innovative. The machine’s frame is a combination of wood, aluminum extrusion, and 3D-printed parts.