Shut-off valve

thingiverse

This shut-off valve can be assembled in just one second. Place the knob into the housing, feed the 4 mm pneumatic tube through the hole and it's ready to use. Turning the knob creates two kinks in the tube, effectively shutting off airflow. These kinks may still be visible after opening the valve depending on the shutoff duration and tube material properties. I'm not aware of how many operations can be performed at the same spot before the tube gets damaged, but we'll find out. Of course, the tube can always be shifted to different positions when the valve is open. If the standard knob doesn't lock well due to too flexible tubes (for example Festo PUN-H), use the Knob_Tight version instead. One of the key advantages of this valve is that it's leak-free. This makes it ideal for shutting off pressurized air tanks for extended periods without losing pressure. I've tested this valve with 4 mm polyurethane tubes from [CompatiblePneumatics](http://www.compatiblepneumatics.com/nr_212_pu-tube-4mm-x-2-5mm-black-package-50m_SL0212535050) using the standard knob, and with Festo PUN-H 4x0.75 mm tubes using Knob_Tight. You can find a mirror of this design on [MyMiniFactory](https://www.myminifactory.com/object/3d-print-100529).