need help with another coaxial

[Cosmic Muffin]

hey guys im having trouble with yet ANOTHER coaxial. but this time i was sure to make the chamber volume bigger.the chamber is about 30cm and the ID is 15mm. the barrel is 7mm and i actuate it with a blowgun and im not sure if i need something bigger or smaller. ill try to get PCGUY to put up my pics cos for some reason i cant do it. plz help

[Cosmic Muffin]

i forgot to mention the problem is that (it wont fire obviously) when i release the air from the pilot valve nothing happens. all tha air comes out when i pilot the piston. BTW i know im double posting but i couldnt delete this post. sorry

[Blitz]

I had that problem with a coax I built -- I solved it by using a QEV as a pilot valve, which itself is piloted by a ball valve.

In other words, use a valve that dumps air more quickly. The easiest way to add this is just to replace your blowgun with a ball valve.

EDIT: I made the presumption that your cannon is using a piston valve to dump air from the chamber to the barrel.

[PCGUY]

-Added the pictures

[Carlman]

EDIT: I made the presumption that your cannon is using a piston valve to dump air from the chamber to the barrel.

thats how all coaxils are..

anyway, the reason it is not piloting is the air from the chamber is refilling the pilot whilst you drain it. so your piston might be too loose in the chamber

[Cosmic Muffin]

yer i tried a 1/2 inch ball valve, a 1/4 inch ( i think) aswell but neither work i cant find QEVs anywhere, do you need to buy them online?

[elitesniper]

whoa that barrel spacer is restricting the flow a ''wee'' bit don't you think?
it might be your spacer.

[MrCrowley]

I had the same problem, a 1/4" ball valve works, but not a blow gun. I think it's down to the pilot volume and how well the piston fits in the housing.

Mine had an o-ring, not enough to require a equalization hole, but enough to make it a tight fit. So it must be my, already pretty darn small, pilot volume. I'll just fill it with bondo or something.

[Blitz]

EDIT: I made the presumption that your cannon is using a piston valve to dump air from the chamber to the barrel.

thats how all coaxils are..

anyway, the reason it is not piloting is the air from the chamber is refilling the pilot whilst you drain it. so your piston might be too loose in the chamber

Not true, some people used diaphragms, especially several years ago.

Cosmic, if your piston is pretty loose inside your chamber, you could make a quickfix by wrapping some duct tape nicely around that piston of yours.

[Pyro Ninja]

Yeah, your piston is probably a little to loose -happened to me before-

[Cosmic Muffin]

well i added an o-ring to the piston after i filed out a groove and i put in an EQ hole. but the same thing happens i just cant figure it out. ill check the spacer tomorrow though. it should work though im so annoyed!

[watto]

That barrel spacer would severely affect performance and maybe even the piston movement...it could also be piston to loose/tight or that the piston doesn't have anywhere to move

[Cosmic Muffin]

nvm guys its working now but i pulled it apart for something else, still u can look at the pics to see what it looks like