Just in time for Summer (Northern Hemisphere, I know).
Print 1 of each part (you can add several of the gears together into 1 print). Some will need to be rotated to lay flat on your bed. No supports are needed. Prints well at .25mm/layer with 3 shells. For most parts, 20% infill is adequate. For the middle wall I recommend 50% or higher, to support the torque on those rather thin pegs.
Pay close attention to the assembly schematics above. On Drive gear A, you want to tighten the two nuts together, NOT tighten either nut to the bolt head.
Fill the reservoir with bubble fluid (water, dish soap, and glycerin) just enough to cover the bubble rings (too much and it will make a slippery mess). Crank the handle and enjoy the bubbles. Right now it mostly makes a single mass of bubbles dangling off the back side, so it clearly needs tinkering. Maybe shaping the impeller case outflow tract into a round tube, right up next to the bubble wheel? Maybe larger impeller blades? Maybe reverse the direction of the bubble wheel's rotation? If you want to tinker with it and make it better, here's the link: https://tinkercad.com/things/jGSvj2vejI9
For anyone wanting a simple hand-cranked impeller fan (also known as centrifugal fan), print everything except the Reservoir.stl, Bubble wheel.stl, Gear strap.stl, and Wheel pin.stl. The transmission results in a ~1:9 ratio of input to output.
Requires:
8 shielded ball bearings, 608 size (22mm OD, 8mm ID, 7mm depth)
2 hex bolts, 5/16", 2 inch length (sorry, don't know if there is a metric equivalent bolt)
Lots of M3 machine screws, 10mm and 20mm length
Several washers meant for 5/16" bolts, roughly 1.5mm thick
This project would not have been possible without the excellent gear generating project here: https://www.thingiverse.com/thing:1604369
