We don’t often get our badminton rackets restrung, but if we did, [kuokuo702]’s PicoBETH project would be where we’d turn. This is a neat machine build for a very niche application, but it’s also a nicely elaborated project with motors, load cells, and even a sweet knobby-patterned faceplate that is certainly worth a look even if you’re not doing your own restringing.

We’ll admit that everything we know about restringing rackets we learned by watching [kuokuo]’s demo video, but the basic procedure goes like this: you zigzag the string through the holes in the racket, controlling the tension at each stage along the way. A professional racket frame and clamp hold the tension constant while you fiddle the string through the next hole, but getting the tension just right in the first place is the job of [kuokuo]’s machine. It does this with a load cell, stepper motor, and ball screw, all under microcontroller control. Pull the string through, let the machine tension it, clamp it down, and then move on to the next row.

Automating the tension head allows [kuokuo] to do some fancy tricks, like pre-stretching the strings and even logging the tension in the string at each step along the way. The firmware has an extensive self-calibration procedure, and in all seems to be very professional. But it’s not simply functional; it also has a fun LEGO-compatible collection of bumps integrated into the 3D-printed dust cover. That way, your minifigs can watch you at work? Why not!

Automating random chores is a great excuse to build fun little machines, and in that vein, we salute [kuokuo]’s endeavor. Once you start, you’ll find stepper motors sprouting all around like crocuses in a spring field. And speaking of spring, Easter is just around the corner. So if you don’t play badminton, maybe it’s time to build yourself an eggbot.