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Tips on quick exhaust valve (QEV) paintball gun?

Posted: Mon Nov 18, 2013 9:10 pm
by AK47
Hey Spudfiles,
I've been making pneumatics for a while, and recently I've been revisiting paintball guns. Keeping in mind that in my area, no paintball parts are available, is there any tips / tricks or problems with a design using a QEV and slide valve connected to a CO2 bottle for a semi-automatic paintball gun? I am hoping to use a pretty simple T-joint, spring loaded clip for loading, any thoughts?

EDIT: Typo

Re: Tips on quick exhaust valve (QEV) paintball gun?

Posted: Tue Nov 19, 2013 7:41 am
by cammyd32
Spring loaded t joints don't often work all that well, you will probably want some kind of blow forward bolt or the like to make sure it loads properly, without one you will probably get double feeds every few shots, also you would probably need a reg somewhere in there, paintballs fired from a QEV setup at unregged co2 pressures are probably above and beyond safe muzzle velocities, lastly you will probably want an expansion chamber for the co2, so it doesn't freeze up on you.
Apart from that, yeah it's a good design, and has been proven to work well in the past, :)

Re: Tips on quick exhaust valve (QEV) paintball gun?

Posted: Wed Nov 20, 2013 6:36 am
by jackssmirkingrevenge
You need to be using low pressure, remember that in a "tee mag" the burst of gas tries to squash the projectiles in the magazine:

Image

Too much pressure and it will burst the paintballs. Also hurt someone :)

Re: Tips on quick exhaust valve (QEV) paintball gun?

Posted: Mon Nov 25, 2013 8:45 pm
by AK47
jackssmirkingrevenge wrote:You need to be using low pressure, remember that in a "tee mag" the burst of gas tries to squash the projectiles in the magazine. Too much pressure and it will burst the paintballs. Also hurt someone :)
I have done some controlled tests without a QEV setup and the pressure is definitely enough to burst the painballs but my hope is that the restriction of pressure provided by a smaller volume of air (courtesy of the QEV) in combination with some room to expand will eliminate this problem. In truth I will probably end up using a 'blow foward' system like that which cammyd32 suggested.
cammyd32 wrote:paintballs fired from a QEV setup at unregged co2 pressures are probably above and beyond safe muzzle velocities.
By safe muzzle velocity, are you referring to a velocity that is 'safe' for what is being shot at or something else like what the setup can handle safely?

Re: Tips on quick exhaust valve (QEV) paintball gun?

Posted: Tue Nov 26, 2013 9:00 am
by jackssmirkingrevenge
AK47 wrote:By safe muzzle velocity, are you referring to a velocity that is 'safe' for what is being shot at or something else like what the setup can handle safely?
The first one.

Exhibit A, courtesy of MrC:

[youtube][/youtube]

Re: Tips on quick exhaust valve (QEV) paintball gun?

Posted: Tue Nov 26, 2013 9:05 am
by jrrdw
Jugs of Truth! Sweet...