Modular boat propeller designed for 3D printing 80mm diameter

by Depronized Aug 10, 2017
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I made a modular 2 bladed prop designed to be powered by a 1hp weed wacker at 7000 rpm... I used ABS with 100% infill, but it would break if the weed wacker was above ~50% throttle when close to 0 mph. I ended up just gearing it down 3:1 and attaching a $10 trolling motor prop. from walmart... The larger diameter was more efficient for my explorer 200 than the 80mm diameter, ~2.5" pitch prop designed for 7000 rpm :)

Your blades looks thicker than mine... I don't bother to research how boat propellers are made and just designed an "aircraft" propeller assuming the air was as dense and viscous as water :) Do you know where I could look for more insight?

attached is a photo of my half-prop.

Yea, ~1000W is a lot. You also have to think about orientation for printing. The materal lines should go all the wy from the hub out to the blade tip undisturbed which means you have to print it basically with the axis of travel aligned with Z. I didn't care about that in this case, this propeller is strong enough for what I intended it for, however I ditched the original project (which was a quite big model outboard) It was too big, and I accidentally asked myself why I should put time into building something like that. :) Now I work on a much smaller water jet instead.

Edit, no i don't know where to find theory about this. My design is purely artistic, but tests with a carbon rod and hand tool in the sink proved it's generating a lot of thrust! :)

Nice design but blade pitch must be steeper to the center of prop (twist)

The blades have different pitch at the tip and the root, most clearly visible in the pic with the three blades on the build plate. Keep in mind that the root is already quite far out from the center of rotation also and the blades are short. But my intention with this modular design is to try different blade designs, this is just a first rough prototype, but runs smooth and creates lots of thrust in my first water tests here! :)