Nice! I'm glad you got it working. I have a quick suggestion: If leakage from the main tank out the release valve is still and issue (although it doesn't seem to be), instead of making a 'minor leak' fit, I think a check valve would work very well. A small check valve would allow the main tank to fill, but once the pilot tank empties no pressure would escape backwards out the main tank.
Good luck, I love back pressure tanks so I can't not love this! If we can get this to a reliable, easily manufacturable state (which you've singlehandedly taken huge leaps towards) then high volume springers will have some serious competition, opening the NIC to much more variety. Truly great job!
The check valve would work great for filling the main tank, I'm just not sure whether extra tape would become the difference between working and the piston not moving at all. For all I know, the cap could just stay stuck and all the air pumped would exit the barrel. It's worth looking into, though.
I am playing around with shrinking to 1/2" CPVC sliding in 21/32 brass. The piston there would need a cheack valve in there...luckily, Zorn has this buddy that fits nicely (with Etape around it) in 1/2" CPVC.Homemade Check Valve
Which takes another McMaster part off the list. We'll see if I did it right later.
In any case, I have INSANE hours at work this week. But there will be down times late at night between things I need to do, so I'm hoping to make more of these as fully functional blasters before the Columbus War on Saturday.
Oh, and darts. I NEED TO MAKE DARTS.
EDIT (Made from my 3DS!! W00t!): the smaller design appears to have worked; more testing commences tomorrow on the viability of the 1/2" CPVC piston.
Edited by Buffdaddy, 07 June 2011 - 11:51 PM.