I am not sure why more people do not know about this, but SMC offers a valve that looks just like the double solenoid but functions slightly differently.
The valve I am talking about has a center off/center pressure/center exhaust feature. Meaning you can have variable piston position using only one valve (not sure if you can get away with one relay quite yet).
The part number differs only slightly from the regular double solenoids. If you are interested, drop me a line. The only catch, currently (as of today) they are on a 4-6 week back/manufacturing order from SMC in japan as no one in the US has any in stock. This valve also fits on the manifold we used last year. (I should also note that those are not in stock either!) Argh
__________________
-Travis Covington
2008-2017 - Engineering Mentor of
Team 254
2001-2008 - Engineering Mentor of
Team 968
1998-2001 - Mechanical Director/Driver/Member of
Team 115