Manual pneumatic valve

This is a manual pneumatic valve (well really two valves) which allows air both in and out of a downstream chamber. I created this to test a robotic arm actuated with pneumatic muscles. The valve is designed to be quick to print and simple to operate, allowing air in and out of the muscles. It makes use of 6mm (1/4 inch) PVC pneumatic tube and avoids applying pneumatic pressure to printed parts which tend to be porous. They have been tested up to 400 kPa (60 psi). This is intended for temporary use, for prototyping etc. as it relies on major deflection (squeezing) of the tube.

Also required for the assembly are two pieces of dia 4mm shaft, each 16mm long (a M4 bolt may do, not tested), two M4 screws with nuts and rubber from a bicycle tube or similar.

There are two valves incorporated in this design. In its default state (i.e. both in and out valves are parallel with the valve body) no air flows in or out of the controlled air chamber. When the in or out valve are lifted air f