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Semi Auto fail!!

Posted: Fri Aug 12, 2011 5:40 am
by django
Guys, I need help asap = I finally got my full Metal 6mm Semi together but it doesnt work right and unsure what Ive done wrong!?

Im using a 1/4" qev
MVVO-3 Normally Open Poppet valve
Small Single Acting Stroke Cylinder
secrewed into an aluminium block I made, problem is the Qev fires when you push the trigger but the cylinder rod stays fully extended and wont retract until you take your finger off the button!? so the gun wont fire bbs.

What the hell have I done wrong???,the Air cylinder or the Poppet?, Im guessing for design gun I need a Normally Closed Poppet valve instead? but then the qev wont work or am I wrong?..


HELP!

Posted: Fri Aug 12, 2011 6:00 am
by Labtecpower
Can you show how you've put it together?

If I understand you, it works like this;

finger off the trigger: filling chamber trough pilot side QEV, Filling cylinder.

Finger on the trigger: Letting air out of pilot side QEV, and should retract the cylinder rod.

Posted: Fri Aug 12, 2011 6:01 am
by jackssmirkingrevenge
A few photos or diagrams will help us help you ;)

Posted: Fri Aug 12, 2011 6:10 am
by Labtecpower
I think this is how it should have worked:

Image

Posted: Fri Aug 12, 2011 6:25 am
by django
I made it the same set up as another member had done on here = it used a Wood Block for the manifold and a vertical tube mag with rubber band holding a cap on or something?.

I cant find the thread though?

Posted: Fri Aug 12, 2011 6:27 am
by jackssmirkingrevenge

Posted: Fri Aug 12, 2011 6:31 am
by django
Heres pics = by my reckoning this should be working
OVERALL COMPONENTS
Image

QEV SCREWS IN HERE
Image

BARREL IN HERE
Image

BB INLET
Image

Posted: Fri Aug 12, 2011 6:43 am
by django
Heres the thread guys, but uses a different pilot

http://www.spudfiles.com/forums/i-too-h ... 21039.html


I Spent a hell of a lot of time and money on this thing,though you wouldnt know by looking at it and very disapointed that it doesnt work?.

What the hell have I done wrong??, the Cylinder rod should stay extended( to hold the next round back) when pressurised then after the Pilot valve button is pressed the rod sould retract at supersonic speed and Qev fire at the same time.

But mine is firing the Qev and rod staying extended then the rod retracts when you let go of the Pilot button!?? but it shouldnt be.......

Posted: Fri Aug 12, 2011 7:10 am
by Crna Legija
django wrote:I made it the same set up as another member had done on here = it used a Wood Block for the manifold and a vertical tube mag with rubber band holding a cap on or something?.

I cant find the thread though?

i think you mean this one

edit dam

only thing i can think of is move the cylinder closer to the qev.

Posted: Fri Aug 12, 2011 7:29 am
by django
Crna Legija wrote:
django wrote:I made it the same set up as another member had done on here = it used a Wood Block for the manifold and a vertical tube mag with rubber band holding a cap on or something?.

I cant find the thread though?

i think you mean this one

edit dam

only thing i can think of is move the cylinder closer to the qev.

How would that improve anything?, Its all pretty much set out the same as the one in that thread except, he uses a slightly different pilot and my Cylinder is smaller (110mm long,14.3mm wide,40mm stroke)

its a clippard M-SSR-08-40 surely running a smaller cylinder shouldnt make it not retract when the pilot is pushed?,it should do so when the pressure drops

I do have a slight air leak on the inlet of the poppet, the leak is before the poppet's actual valve itself so shouldnt effect it's operation

Posted: Fri Aug 12, 2011 8:32 am
by MrCrowley
Have you tried operating the cylinder when directly attached to the chamber port of the QEV? Even if it doesn't work when directly attached to the QEV, you will still learn information about your problem.

Posted: Fri Aug 12, 2011 9:00 am
by django
MrCrowley wrote:Have you tried operating the cylinder when directly attached to the chamber port of the QEV? Even if it doesn't work when directly attached to the QEV, you will still learn information about your problem.
No I havent mate,It has me completely baffled but if I cant get it working I'll have to take it apart and try that but its all loctited together and a pain in the ass to peice together due to the configuation of it :roll: .

Its pretty much like the Air cylinder is working in reverse!?!


EDIT:
Just fixed all air leaks and now has heaps more powa but the cylinder still is not functioning right!? WHY!!!

Posted: Fri Aug 12, 2011 9:38 am
by LovableAirGuns
You have got the same 3way as me although i set mine up differently you should see my thread its pretty much the exactly the same as yours.
i would post a link but im on my phone :/
its called: semi auto air rifle bb gun
i think thats what it is called but just go to my account and go to posts made by lovableairguns

Posted: Fri Aug 12, 2011 11:08 am
by Gun Freak
Something must be wrong with your cylinder. If it is single acting it should retract as soon as you press the trigger. I think you should have connected the chamber and cylinder with a hose instead of fittings. That would make it easier to disassemble. Why did you use loctite?

Posted: Fri Aug 12, 2011 11:56 am
by django
I used Loctite cause I was sure it would all work but it doesnt!??.

I used Fittings/loctite to make it all secure,If I used hose to connect the air chamber to the Cylinder then the whole assembly would be more prone to flop about!.
100% cylinder is Single acting