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Homemade QEV?

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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Homemade QEV?

Unread postAuthor: Haniball1337 » Thu May 02, 2019 1:24 pm

Hi guys , i need yours help again yee. I wanted to build qev valve beacuse they are expensive in my country :( But it leaks and dont work
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Haniball1337
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Re: Homemade QEV?

Unread postAuthor: jackssmirkingrevenge » Thu May 02, 2019 2:28 pm

this is your problem

The surface that the piston pushes against has to be flat and polished.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Homemade QEV?

Unread postAuthor: farcticox1 » Thu May 02, 2019 3:43 pm

I made a QEV with a 1/2" T and it works really well

QEV 02.jpg
QEV 02.jpg (12.17 KiB) Viewed 1254 times


qev T.jpg


This is the sealing face, I turned it in a drill press and used a file to shape it.
qev stub.jpg


Piston is made from a nylon block with a hard rubber face.
piston (1).jpg


piston (2).jpg


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Re: Homemade QEV?

Unread postAuthor: Haniball1337 » Fri May 03, 2019 5:14 am

I polished the surface and nothing its leaks , but maybe the problem is that the sealing face is too short? idk
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Attachments
piston take all chamber.jpg
short sealing face.jpg

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Re: Homemade QEV?

Unread postAuthor: Haniball1337 » Sat May 11, 2019 10:28 am

I made something similar to this QEV https://www.youtube.com/watch?v=8zvUMFqUVcI , My piston is made from hot glue and rubber washer glued , and its slide easily in the nypel . But when i am trying it , air flies out from pilot . Air is little escaping from port R (exhaust?)
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Attachments
g.jpg
a.jpg
b.jpg
c.jpg
Sealing face
d.jpg
Piston
e.jpg
f.jpg

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Re: Homemade QEV?

Unread postAuthor: jackssmirkingrevenge » Sun May 12, 2019 4:51 am

Haniball1337 wrote:But when i am trying it , air flies out from pilot . Air is little escaping from port R (exhaust?)


When this happens, it's usually because the piston is not tight enough in the tube it is traveling in. Try wrapping it with tape until it is snug.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Homemade QEV?

Unread postAuthor: Haniball1337 » Sun May 12, 2019 7:46 am

I did that , piston is little snug it works but very poor , its not loud and air leaks from the exhaust port so i have 6 sec to shoot untill air escape
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Re: Homemade QEV?

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Re: Homemade QEV?

Unread postAuthor: farcticox1 » Sun May 12, 2019 10:02 am

Sounds like it is still not sealing on the rubber face
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Re: Homemade QEV?

Unread postAuthor: Haniball1337 » Sun May 12, 2019 10:16 am

The sealing face is polished and sharpened
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Re: Homemade QEV?

Unread postAuthor: Surfer_wlan » Tue May 14, 2019 8:40 am

Try softer rubber on the seal face.They sell this white "kinda foamy" sealing. Then maybe a slightly more powerfull spring that pushes the piston. And to prevent leaks, you may use epoxy glue instead of teflon tape on some threadings (which need not be dismantled for servicing or testing).
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