This is our last area of design need. A multiposition pneumatic would do the job just perfectly. Barring the use of a second solenoid to meter the exhaust, it is not possible. To be able to use the metered exhaust will likely require a human touch that an auto program cannot handle consistantly.
I did have an idea to gang two cylinders in series. Have something like an 8 inch throw connected to a 12 inch throw gives you four positions. All in, 8 out only, 12 out only, all out....
Anybody considering something like that? Our engineering crew is meeting with the students on Thursday and then we have a Saturday build session planned where I hope to put the wraps on this last design item.
