This is a snap together version (some glue) of my printable motor. It has been shrunk and uses only 9 pieces, air pistons included.
The bellowPiston part is printed with no infill and needs to be airtight. When inflated it extends outward to push the glued on bellowLink part. The bellowLinks then push the wobbleRing, meshing with the drivenGear. Each piston is inflated and deflated sequentially to "step" the motor 4 degrees forward or backwards.
This thing is the successor to this:
And uses sgcg's fastener library
Also uses mechadense's epi-hypocycloids from:
The bellows used are modeled after this general shape:
Though I hope this latest version shows much improvement, I realize there is always room for better design. Please, chime in if you see room for improvement.
I also have to mention that I have not printed this yet, so I don't know if it will work. Of biggest concern are the bellowPiston parts, because they need to extend at least 2mm to be productive. I also don't know how easy it will be print 45 degree overhangs that are airtight AND slightly flexible.
All parts are oriented for printing without support.
Print 1 each of the following:
Print 3 of both the bellowPiston.stl part (without infill) and the bellowLink.stl part.
Open the bellowPiston parts at the top end by taking off the last layer.
Glue together the bellowPistons and bellowLinks.
All pieces snap together downward from were they are seen in the exploded view.
The wrsmAssembled.stl file shows the completed thing, minus gluing.