Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
If it's not "pulling back"... Your piston isn't moving backwards, it is because of a bad pilot or a bad sealing piston... It's not rocket scientist... When a vacuum doesn't pull an object, it's not a strong enough vacuum...
I have no idea why you spent $40 on a sprinkler valve, when you can buy one for less than $20... I can get them for $10... You can even make a small barrel sealing tee and use it as the pilot.
-FrOgY-
I wish people would stop needing a better signature!
It wasnt just the sprinkler valve ($14), I had to buy pvc and copper fittings $12, a blowgun $7, and more pvc glue $6 because I ran out. It all adds up.
frogy wrote:If it's not "pulling back"... Your piston isn't moving backwards, it is because of a bad pilot or a bad sealing piston... It's not rocket scientist... When a vacuum doesn't pull an object, it's not a strong enough vacuum...
I have no idea why you spent $40 on a sprinkler valve, when you can buy one for less than $20... I can get them for $10... You can even make a small barrel sealing tee and use it as the pilot.
So how can I fix this? My pilot cant be bad because I tried 2 different ones already, if the barrel didnt seal, I couldnt pump it up to 90 psi without it leaking and my piston is lubed and I can pull it back very easily with my hand.
A bad rear seal on the piston is pretty hard to describe... If your barrel isn't leaking and the gun fills with air fast, your problem is your rear of your piston not making a good seal with the tee...
The rubber on the back of the piston should be straight and stiff, so that it contacts the sides of the tee pretty tightly... You'd think that this would make the gun not fill, but this is not the case... Explaining it simply, if air wants to get through, it will find a way... Your gun's chamber may fill slightly slower with air...
But, when you pilot the valve, all the air will be pulled out from behind the piston, and since there's less of a gap for air to just slip around the piston, the air will actually push the piston backwards and escape out the barrel...
If you can't cut your rear gasket very round, it's probably best you oversize it, or invest in o-rings so your piston seals better...
-FrOgY-
I wish people would stop needing a better signature!
OMG I THINK YOU'RE RIGHT!
There is no rubber on the back of my piston lol, just the end of my deoderant can. I was going to try to describe how the air was getting straight from the chamber to the valve, but decided it was too complicated. I'm, going to modify my piston tomorrow, Thanks for the help.