Pen Gun Wont Seal

[spudkilla224]

hello, i made a pen gun like jacks, and it wouldn't leak air out the barrel when i used my lips to test the seal, but when i use my bike pump, or the aircompressor regulated down to like 5 PSI, air just leaks out the barrel.

does anyone know if i need to make a small homemade pump for this pen gun.

i know the piston moves foward when air is put through the schrader valve. but when i take the air pump source off the schrader all the air comes out.

did you guys that built similar pen guns have this problem? and if so what did you do to fix it?

Thank You For Your Time

[sniper hero]

I got same problem never finished it
maybe the barrel is not in a 90 degree angle and flat
maybe the seal isn't proper
maybe it is the pump
I still want to make one so I will try make one soon and which problems I solved
post a pic someone might see a problem

[jackssmirkingrevenge]

As above, show us some more details of your actual setup and we'll be in a better position to advise you

[ramses]

I think you are loosing air through the schrader when you take it off. This means you could be actually piloting your valve. If you have it loaded at pressure and you take the air off, it may actually fire.

The solution: use a bigger pilot volume, bigger equalization hole, a valve, or just remove the air to fire.

[jackssmirkingrevenge]

i know the piston moves foward when air is put through the schrader valve. but when i take the air pump source off the schrader all the air comes out.

If no air leaks through the barrel while you're pumping, then have a look through this thread

To fully enjoy the benefits of a small calibre pneumatic, and if your launcher can take the pressure, I would recommend buying a shock pump though to go to the 200-300psi range