Using a spring to seal a piston?

[spudkilla224]

Hello everyone, i'm building a new piston valve aircannon and I have the problem were the piston won't seal foward its self. But it will exhaust perfectly fine. I have to push the piston to seal against the barrel to make it work.

So I was wondering how can I use a compression spring to push the piston foward to seal against the barrel? And be able to attach a bumper to the spring in the back of the tee?

The piston cannon is serviceable.

Any help would be appreciated!

Thank You!

[velocity3x]

I have to push the piston to seal against the barrel to make it work.

[geardog32]

im assuming this is a t fitting valve. i would say if you are filling from behind you need a larger piston so that when you fill the small chamber behind the piston builds faster than the tank pushing it forward. if you were to use a spring i would say a very light one, just enough to move it forward.