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My first gun using QEV 20bar

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Do I dare to take it up to 15 Bar?

YES
11
79%
NO
3
21%
 
Total votes : 14
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Unread postAuthor: Brian the brain » Tue Aug 14, 2012 12:53 pm

Can you explain the hold in the cylinder a little more, maybe add a picture or something. I just got the exact valve in the mail today and I'm interested in making the modification. Thanks

I don't understand the question..
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: slugguy » Tue Aug 14, 2012 1:07 pm

I misspelled the word "hole." I spelled "hold" by accident. On 8-8-12 at 15:52 you said to punch or drill a small hole in the piston of the qev. I didn't understand what you meant, where you meant, or what it is for. I'm just starting out with a qev myself and would like to make any modification that would help the gun. Thanks for your help.
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Unread postAuthor: Brian the brain » Tue Aug 14, 2012 3:12 pm

Don't puncture the middle part where it seals the out-port and don't get to close to the edge of the piston as it might tear by the repeated stress of firing.

It's that simple.
Air coming from the reservoir will repressurise the pilot area as soon as the pilotvalve is closed and the piston will be pushed back against the port and seal again.

Now..if you want to pressurise the gun ( pump, compressor,whatever)
directly into the reservoir( wich can't be done with an unmodded qev), you need to put a weak spring behind the piston or it will get blown open by the incoming air.

So a spring will enable you to fill "chamberside".
This will help reduce the numer of fittings on the pilotside.
less bulk and smaller pilotvolume wich helps performance.

The hole is what makes the valve able to "repeat".
If that hole becomes too large it will hurt performace as the air just rushes out the pilot through that hole.
Keep it small!!
about 2mm should work..
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: slugguy » Tue Aug 14, 2012 3:17 pm

Cool. Thanks so much for taking the time to go through all that.
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Unread postAuthor: Brian the brain » Tue Aug 14, 2012 3:33 pm

:D

It you then use JUST a safety pop-off valve as a pilotvalve ( nothing more!!) and fill the chamber at high pressure and high flow and you get this:
( and build the blowback system to feed ammo offcourse)

Notice all I have to do is squeeze a blowgun to feed pressure into the chamber...and off she goes..
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Last edited by jrrdw on Thu Nov 07, 2013 1:23 pm, edited 1 time in total.
Reason: Removed video link, video unavailable.
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: GustavssonB » Mon Aug 20, 2012 12:45 pm

BTW: with a well made hammervalve all your components should be able to handle 20 to 25 bar.



The gun has now been tested with 20 bars pressure:D and its still holding nicely:)
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Unread postAuthor: truemanator » Wed Aug 22, 2012 7:41 am

How Did you make that adaptor for the extinguisher, and also, how do you fill it up, i cant see a filling valve anywhere?
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Re: My first gun using QEV 20bar

Unread postAuthor: GustavssonB » Wed Aug 22, 2012 7:52 am

I welded the extinguisher to make it a different thread sice. The air is pumped on the pilot side of the qev, were the quick connect is:)
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Last edited by GustavssonB on Wed Aug 22, 2012 8:12 am, edited 1 time in total.

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Unread postAuthor: truemanator » Wed Aug 22, 2012 8:00 am

y exactly did u repost that??
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Unread postAuthor: GustavssonB » Wed Aug 22, 2012 8:04 am

Haha wtf, wasn't going to repost that... I tried to change the title, not sure on why that happned:/
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Unread postAuthor: archie370 » Fri Sep 07, 2012 8:31 pm

This is pretty cool what kind of welder did you use for the fire extinguisher ... ?
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Unread postAuthor: GustavssonB » Sat Sep 08, 2012 5:50 am

archie370 wrote:This is pretty cool what kind of welder did you use for the fire extinguisher ... ?


Thanks, i used i MiG welder for the extinguisher:)
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Unread postAuthor: archie370 » Sat Sep 08, 2012 8:44 pm

Oh yeah :) you must be a pretty good welder for it to be safe :) ... i thought it would be a special welder for welding stainless but obviously its not stainless haha ;)
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