Solenoid Pneumatics Help

[QRohlf]

Pneumatics are limited by the elementary gas law that states that a gas will fill its container. Meaning that you really can't physically have any more control than all the way in or all the way out on a standard pneumatic line cylinder.

There are some workarounds, however. While you cannot directly control the volume of gas present in the cylinder, you can control the pressure of the gas in the cylinder. This means that if there is enough resistance against the cylinder, it won't open all the way at low pressures. You *might* be able to accomplish this by either rigging both a full-presure (60psi) line and a line that's been regulated down to half-pressure (or less) to a T attached to the cylinder, then activating one of the two lines for position control, or by pulsing the pneumatic reed switch very quickly so that the cylinder isn't fully pressurized before the reed switch shuts off the flow.

I have never tried either of these methods, and I doubt either of them would work terribly well.

As an alternative, Bimba does sell 3-position and electronically positioned specialty cylinders. I've never used these and don't know about usage or cost, though.