Moineau Pump
Description
I thought this might be useful as a paste extruder or something of that nature. It's better than a peristaltic pump because no flexible hose is needed (which tend to reduce efficiency and wear out), plus it doesn't pulse.
Instructions
The rotor slides down into the stator; it's a tight fit, but that helps it seal. Once it's lubricated by whatever you're pumping, it'll go easier. The crank twists onto the rotor; no need for glue. It'll stay tight as long as you're pumping the right way (fluid moving toward the crank), but it'll fall off if you turn it backwards.
No need to prime the pump, just submerge the base in fluid and crank away.
A parametric OpenSCAD file is included so you can change the parameters to suit your needs. It will display the pumping rate based on your choices. You can also change the tolerance, though I found it works fine with zero, just relying on the flexibility of the plastic. I also made the wall thickness exactly two tread-widths wide, so the dimensions would be accurate. You may want to change this for your printer.
UPDATE: Thanks to Proton for making an animated version of the OpenSCAD file. This version is now included, so you can control the animation for yourself.
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In commercial pumps they use two main methods to hook up the motor; a double U-joint (cardan joint) or a slim flexible shaft. I bet you could punch a hole part way down the rotor and run a skinny shaft up it, sticking out a ways. The shaft needs to be torsionally stiff, but flexible side to side. It needs to have some length to it to allow the side to side motion of the rotor.
For this low powered application a sneaky way to do it would be to set the motor up in a slot so it can slide side to side with the rotor, perhaps with some gearing to make that motion happen the way you want it to. You might be able to generate the right motion with an eccentric on the motor shaft also.
If someone were to attach a motor to this, a mini Schmidt coupling might work great! http://www.thingiverse.com/thi...
Removed bumps and jumps from Proton's beautiful animated .gif's of this intriguing mechanism.
Very cool! Mine works but where the steps go in for the extra shell makes a tight spot when turning, going to try again with 0 extra shells otherwise it works great!
Kool stuff! I printed one last night and played with it earlier today.
Just an idea, but it would be cool to add some sort of spout to the top of the stator.
Wonderful and useful design!
Wondering how such a thing can be driven by a motor, I animated it.
Apparently, you can drive it with a planetary arrangement since the inner spiral describes a hypocycloid.
Nice job animating the SCAD file, and thanks for sending to me. I've updated the SCAD file here to your animated version. Indeed, a planetary arrangement should work nicely. If you're interested in motorizing this, perhaps using my 1:246 gearbox, that would be fantastic.
License

Could someone please make the stator thicker like 5mm. I know there is a openscad file but i don't really understand what I would change.