3D Modeling a Mini Wind Turbine
Several months back I posted on the Fediverse about a wind turbine project I was working on for a university class - sharing my troubleshooting efforts as I try and power through an interesting problem. A few people replied saying that they'd love to hear more, so now that the semester is long over I want to share a bit about the project!
The goal of the project was to design a small wind turbine capable of being pushed by a leaf blower and generating enough power to turn on 2 small LEDs. The overall cost of the turbine had to be less than $5, so most were built out of recycled materials from around the house. I decided to re-teach myself 3D modeling and design something in OnShape and print it out on my Prusa MK3.
It took 3 iterations of design for me to reach a successful one, but all 3 were based on the Savonius design - using "scoops" to catch the wind and push a vertical axis mechanism for generating power. I started out with 2 blades overlapping each other, but it wasn't able to generate enough force and stalled out. I think I could likely have gone with a similar design but smaller so the weight of the turbine itself didn't impact the force too much - but I decided to go for a re-design anyways.
One of the hardest parts of the design, in my opinion, was creating a mechanism for attaching the turbine to the generator - leading to my 2nd failure. I increased the number of blades to 3 and it seemed to do alright! However, to attach the blades to the generator I printed out a coupler attachment, that would connect the main body to a wooden rod, and the wooden rod would be the piece sitting in the generator. The coupler piece broke multiple times in my testing attempts, and I really struggled to update the design to something that would consistently fit the tolerances my printer could make, be small enough to not impede on the mechanism, and be strong enough to not break. The coupler breaking multiple times led me to the 3rd and final iteration and its changes.
The coupler mechanism stayed mostly the same, however some slight modifications were made to make it thicker and give a bit more tolerance. This led to a successful final outcome without it breaking! I also printed it as one solid piece instead of 4 as I was previously doing, removed one wall to reduce filament usage, and increased the overall size of the blades.
The final design comes out to a total dimension of 130x130x66.5mm, ~6 hours of print time, and a cost of $2.15 for both the main part and the coupler - all printed in PLA. The printed piece is connected to a very cheap wooden rod with superglue bringing the estimated cost to $2.78 per turbine. It was able to catch the air from the leaf blower incredibly quickly and get up to full speed, providing enough power to make the LEDs incredibly bright and successfully accomplish the the project.
Prior to this project, I didn't have a ton of 3D modeling experience. I had previously made a few simple things in TinkerCAD, and had added embossed letters to an existing design, but most of my 3D printing experience came from using other people's models.
Working on this got me a ton of useful experience in the trial and error of 3D modeling for real world projects and I learned a ton. Looking back, I wish I would have focused on a program like FreeCAD instead of OnShape, but the foundations were certainly beneficial and I look forward to working on future projects in other available tools.
This project really encouraged me to model my own 3D prints more, and I hope to continue to do so in the future! I'm still looking for inspiration on my next major printing project, but first I've got to get other projects down the pipeline! I hope anyone reading this enjoyed the project summary and I look forward to writing and sharing future projects. :)