piston valve help

[spudtyrrant]

i have made a 2" barrel sealing, piston valved, pneumatic it works fine up to 40 psi, it seals and doesn't leak but beyond that when i fire it it releases a lot of air from the sprinkler valve and then fires 2 or 3 seconds later very weakly here is a crude picture of it PLEASE HELP

[Gippeto]

First, let me say,...I hate Image shack and their pop up ads.(party poker)

Yeah, I know,...it's free. Just venting.


Anyhoo;

Likely, your piston is (way) too loose.

Give the piston a wrap or two of duct tape to verify whether that IS the problem, and post the results.

Lay the duct tape on smoothly, that's important.


Aside from that, if I assume your diagram to be "remotely" to scale, a couple of things present themselves.

1) The barrel should (IMO) extend further into the tee, nearly to the middle.

2) You have too much pilot volume. Although opinion varies, total piston travel should be between "slightly more than d/4" to d/2 (JMO) (d being the barrel diameter)

[spudtyrrant]

ty so much duct tape was to big to fit in the gap so i use teflon and now it fire amazing at 75+ psi i had to run inside tho i didn't think it would be that loud the diagram i drew was just a basic overlay i didn't take the time to measure how far anything went into the chamber but i know the pilot volume is around 1 1/2 inches i now have the problem of the teflon tape coming off every 4-5 shots can anyone tell me something as thin as teflon that will stick to the piston