How To Make A High Power Air Cannon - 2" Piston Valve (Barrel Sealing)
Added 2017-03-30 23:42:17 +0000 UTCEarly access for Patrons! Thank you for your support!
Comments
Try TFE pipe thread paste, that often works to make the rubber stickier and get a seal. I don't think that instant gasket will work, probably just make the surface less even. I should have made a bigger point in the video about making sure the inside end of the valve output is cut and smoothed perfectly flat. That's the biggest culprit in sealing issues. You can make it seal better also by reducing the size of the hole in the piston, because it will cause the piston to press forward much harder when an air supply is first attached as it takes longer for the chamber pressure to equalize.
NightHawkInLight
2017-04-24 16:39:13 +0000 UTCWell, thanks for the discussion! Turns out it's all moot at this point: the piston doesn't seal against the rubber coupling, so air just leaks through the cannon. I'm trying to see if I can patch it by slathering the inside of the coupling with instant gasket, but I'm not hopeful. I'll keep you updated...
Steve Koplin
2017-04-23 19:26:48 +0000 UTCA one way valve on the piston is a great way to go if you can find room for it without hitting the housing when the piston moves. Reducing the volume of the chamber might make it so the cannon does not fire at all. When you open the firing valve you're in a fight to reduce the pressure behind the piston faster than air can leak back through the piston from the chamber. If the chamber is small it doesn't take much for the chamber to drain before the pressure differential is great enough to move the piston, especially if the hole in the piston is already over sized. It's pretty easy to reduce the size of the hole in your piston if necessary. Just clean it and cement some PVC shavings in there to choke it off.
NightHawkInLight
2017-04-23 15:38:20 +0000 UTCHmmmm... I kept the hole to 1/16", the smallest bit I have, but the relief valve output is significantly smaller than the ball valve, which could pose an issue. I guess a few ways to overcome this would be to a) reduce the volume of the pressure chamber to achieve higher pressures for a smaller amount of force; b) introduce a one-way flap on the piston hole; or c) use a sprinkler valve to allow easy and rapid pressure release
Steve Koplin
2017-04-23 12:56:31 +0000 UTC
