A simple but good working compressed air engine. It works even with your lung, no pump required! I designed it because i wanted to make my own motor and develop my design skills and my knowledge about tolerance in 3D printing. Im also fascinated how simple it is to build such a nice engine.

Parts you need:

• 4 M3x16mm screws with nuts for the casing
• 2 M3x12mm screws with nuts for the cylinder and the crankshaft
• 1 M2,5x14mm screw (It is placed at the top of the "Ventilhebel" to adjust the opening time of the Valve. Cut away the head of the screw and make it a bit smaller at the top for more air flow)
• 1 6mm BB (from a Airsoft gun for example)
• 1 O ring with inner diameter: min. 5mm and outer diameter: max. 7mm
• 1 Ball Bearing with inner diameter of 8mm and outer diameter of 22mm
• some sealing paste to prevent "Gehäuse" and "deckel" from leaking
• Glue for the parts of the casing

Use a little bit of the sealing paste to fix the O ring in its position. If you didn't the o ring goes out of its position.

The Valve I used is a ball valve. Put the O ring in the upper hole of "Deckel" and the Airsoft BB on it. Then check if it's leaking or not.

I hope you have fun by building and using it. I used parts I already had at home. Maybe you can find the required things at your home too. Feel free to ask me if you have any questions!