Full auto qev pop off problem

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Dembouz921
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Sun Sep 11, 2022 10:53 am

I'm making a qev full auto with a blowgun connected to the chmaberside and a compressor pop off valve. My air supply is a 0.2 L paintball tank with a modified preset to ~10 bars. I can't make it cycle full auto i've tried tweaking the pop off valve which can be unscrewed to apply more tension on the spring but it doesn't help, the air is either escaping from the pop off or blowing the qev open.

I think the problem is the pop off, what pop off valve are you using? Any idea on what pop off should I use or what can I tweak to make it work.
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jackssmirkingrevenge
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Fri Sep 16, 2022 10:44 am

If you're filling from the chamber side, did you make a hole in the piston so the pilot area can be filled?

For this one I had replaced the piston with a delrin disc, and added a spring to reset it:

hectmarr wrote:You have to make many weapons, because this field is long and short life
Dembouz921
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Fri Sep 16, 2022 12:56 pm

Yea I ve made a 1mm hole in the piston and put a spring to reset it. After tweaking the air flow coming in the Qev and my chamber volume i manage go get a high rate of fire full auto but it is way too fast. In your video you are able to get a pretty slow rof, so I'm guessing the problem is the pop off. It's a rubber piece pushed by a spring which is blocking the exit hole. Maybe those type of pop off doesn't have enough air flow, what type of valve are you using for the pop off?
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jackssmirkingrevenge
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Fri Sep 16, 2022 2:10 pm

Here's the internal parts of that valve:

Image

The "piston" was a brass cup with a rubber insert, what does yours look like inside?
hectmarr wrote:You have to make many weapons, because this field is long and short life
Dembouz921
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Sat Sep 17, 2022 5:28 am

How do you post pictures, it will be simplier to show my setup. My pop off valve is actually similar to yours expect it's shorter. The problem can also be the spring in the Qev, your spring look softer than mine. You said before you have replaced the piston with a delrin disk, does this means full auto won't work with the regular piston with a hole?
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jackssmirkingrevenge
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Wed Sep 21, 2022 11:57 am

Use the "attachment" tab in the "full editor & preview" reply window:
342-FH_001071.jpg
does this means full auto won't work with the regular piston with a hole
I did this to avoid damaging the original rubber piston, however other forum members have made this modification successfully for similar setups.
hectmarr wrote:You have to make many weapons, because this field is long and short life
Dembouz921
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Sun Sep 25, 2022 2:05 pm

Thanks for your help I actually made it cycle well by increasing the pressure of the air coming out of the preset. I now need to figure out how to prevent bbs from rolling out of the barrel, I m using an AEG magazine so there is spring pressure, the gun uses a blow forward valve to cycle the bbs.
20220925_210155.jpg
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