Pneumatic rotary engine: R-66

The R-66 is a continuously rotating pneumatic rotary engine. It is not a stepper motor, so no complicated valve manifold is required to get it running. One pressurized pneumatic line is sufficient. Video: https://youtu.be/Nayswdk_PZ0

Multiple versions are available for the pneumatic connections (4 mm tube or M5), piston type (conventional or monolithic) and front rotary plate (solid shaft or hex bit). Seal cutting tool can be customized with [thing:3020690](https://www.thingiverse.com/thing:3020690).

Enjoy creating and running this motor! If you have any questions, just ask.

June 10, 2019: A better design is available: [R-52](https://www.thingiverse.com/thing:3668776)

Sept 15, 2018: Added version 2 of BackPlate to allow better fixation of the crankshaft screw, Crank_Rear to allow insertion of a M3 lock nut and Rotor_Front_Acrylic_3mm to allow internal inspection while running.