Will this semi-auto QEV design work?

jmez1996 · Thu Feb 10, 2011 5:33 am

okayyy so i have recently bought this QEV http://cgi.ebay.com.au/Pneumatic-Quick- ... 1330wt_702

im am planning on implementing it as shown in the diagram below and using a regulator between the tank and the QEV to allow for multiple shots.

my question for the pros is whether or not this would work? or if the valve would not re-pilot because the air is entering the tank side of the valve? in this case would i need to put the tank behind the pilot so that it repilots after each shot?
i only plan on getting 5+ shots. using a barrel of about 6mm inside diameter.

i would also be willing to use a ballvalve inplace of a regulator if it is going to work.
any help would be appreciated as i am new to QEV's.
thanks.

lemming124 · Thu Feb 10, 2011 6:03 am

should work fine. The QEV will reset itself if it has a spring (I think they all do), ball valve will work in place of a regulator but you'll have to open and close it for every shot.

Alternatively you 3 way mod the blowgun, put the reservoir where the schrader is and reduce the "tank" size.

also, a QEV is works the same way and is similar (in terms of structure) to a homemade piston valve with a spring bumper, it's just more efficient and faster and shouldn't require servicing.

AnotherSnappedLine · Thu Feb 10, 2011 7:48 am

My build is sort of like that- Instead of air pressure behind the piston, Im adding a spring and filling the chamber from behind. I can mod the blowgun actuator by adding a spring-loaded screw to regulate flow.

Crna Legija · Thu Feb 10, 2011 8:00 am

youd be better of just putting a tiny hole in the piston of the qev and adding a very weak spring behind it, then just filling from chamber.

jmez1996 · Thu Feb 10, 2011 9:33 am

okayy so hopefully it will work but i cant test it till it arrives..
im only worried that that the QEV will pilot on the first shot but then not again as the air is coming from the other side...

Crna Legija · Thu Feb 10, 2011 10:42 am

if you don't put a spring behind the piston and a small hole in the outer edge of the piston then it will not work, and if you do it then might as chamber fill and reduce you pilot volume