This "Weeny" Soldering Bot, Powered by a Raspberry Pi, Takes the Drudgery Out of Manual Soldering

Pseudonymous maker and YouTuber "iforce2d" has built what they believe to be "the world's smallest LinuxCNC build," creating a compact desktop soldering robot using a WeenyPRU board and a Raspberry Pi single-board computer (SBC).

"The reason I wanted to have a machine like this," the maker explains, "is because I'm starting to have more and more of these IO [Input/Output] mixer boards to assemble, or at least partially assemble. They arrive to me from JLPCB and to get them into this state we need to add 112 pins, which I've been soldering manually so far."

Soldering 112 header pins is fine for short runs, but for larger volumes quickly gets boring — which is where the "Weeny Solder Bot" comes in. Designed to add programmable real-time capabilities to a Raspberry Pi in as small a form factor as possible — hence "Weeny Programmable Real-time Unit" — using an STMicro STM32F103C8 "Blue Pill" microcontroller. With this, the Raspberry Pi gains four-axis stepper motor control at up to a 50kHz step rate, a 10kHz spindle PWM control, 14 digital inputs or outputs, two analog inputs, a rotary encoder, RGB LED strip control — because why not?

This compact yet feature-packed board is then used to create a device controlled by LinuxCNC, though a custom G-code interface, which can solder each pin automatically — taking the drudgery out of assembly, though not quite as quickly as a hotplate or wave-soldering machine. The finished joints aren't the greatest, either — with a few dry joints and several bridges — but it's enough to prove the core concept, at least.

The full project video is available above, while iforce2d has released source code for the WeenyPRU on GitHub under the reciprocal GNU General Public License 2.