Double Helix Pump

thingiverse

This is part of a kinetic sculpture I designed called Digital Rain, which is based on my gyroid construction set, remixed from elsewhere. It's best experienced in person, but since it's currently stored in my basement, a video will have to suffice: https://youtu.be/fdcw1tt5CR4 As a modular design, you can easily scale this up to any height you desire - mine stands at 10 units high, approximately four feet. I power it with a 12V gear motor sourced from eBay, which I run at 6V to achieve a speed of about 15 RPM. This requires only a few watts of power and is pumping around 1,500 5mm steel bearing balls. Post-Printing Assembly This pump and track system requires no glue or fasteners for assembly; it all simply fits together. The track pieces have two little ears to prevent them from curling off the print bed; these need to be trimmed before assembling. I mounted the motor underneath the lid of a wooden box and secured the bottom of the pump with double-sided tape to the top of the lid. The drain and collector pieces are linked through mosquito netting with a small hole cut in the center, providing a reliable way to collect balls from a wide area without generating excessive noise. Designing This Project The main body of the double helix pump was designed to be an efficient and visually appealing means of lifting a large quantity of small steel balls. I chose this design because it doesn't require precise tolerances: the rotor is significantly smaller than the stator, but the balls act as a bearing, keeping everything centered. The track is designed so its own weight keeps the segments locked together, forcing the balls to flow in single-file and preventing them from getting stuck. Most of my design iterations focused on subtleties of the drain and top of the pump to ensure reliable operation without balls becoming stuck or escaping. I've run this for more than an hour at a time, and so far, it's withstanding the test.