FAILED: Positive displacement screw pump

thingiverse

I wanted to build a tower garden with an integrated watering system. To make this happen, I needed a pump that could deliver water to the top of the tower. Since my garden would be about one meter high, I required a pump capable of providing one meter of head pressure. I ruled out centrifugal pumps and decided to design a positive displacement pump instead. Positive displacement pumps work by moving a fixed amount of fluid per cycle, making them well-suited for higher pressures. I chose a screw-type pump because it seemed like an exciting idea. After printing the screws, however, I realized this project was likely doomed. Even when pressed together tightly, the 3D FDM tolerances left visible gaps between the screws. When I printed the top component and tested it with just the screws, one meter of head pressure caused water to flow between the screws and even penetrate the layers of the print. Given these issues, I decided not to complete the pump design. If anyone has suggestions for improving this type of pump, I'm still eager to experiment. What I learned from this experience is that 3D printing isn't accurate enough for a pump handling water's viscosity. One meter of head pressure demands either post-processing to prevent leaks or a printer with better print quality than mine.