QEV, 3 way valve, slide valve help

[1nxtmonster]

So..... i'm pretty close to finishing my qev airsoft gun. But the slide valve isn't really working well as a trigger b/c of friction, consistency, etc. So what kind of manual 3 way valve would work well as a pilot for a qev that could be filled through, then when you trigger it it blocks off from the supply and pilots the qev? (Like a slide valve)

Thx

[jackssmirkingrevenge]

have a look here: http://www.spudfiles.com/how-to-databas ... ml#p366079

[1nxtmonster]

I wasn't able to find in that thread if those 3 ways were normally open or closed. Do you remember?

[jackssmirkingrevenge]

Normally open, but Brian suggested a good way to fix this:

[1nxtmonster]

Ahhh...how bout this: http://www.ebay.com/itm/MEAD-MV-50-NEW- ... 35c017e55b

Due to size constraints, i'm not sure if it can fit in the gunstock. So I was doing some thinking, and came up with a shut-off valve:

Screen Shot 2014-02-08 at 11.58.18 AM.png (28.63 KiB) Viewed 7801 times

[jackssmirkingrevenge]

How does the "shut off valve" work exactly?

[1nxtmonster]

What it was supposed to do, was work like a slide valve in the fact that it should shut off the air source while piloting. I built one, and it kind of works, but not really any better than just putting a flow restrictor in place behind the pilot.

If I make a cast epoxy qev piston, and spring behind it, could I chamber fill and pilot from behind with like a blowgun or something simmer?

[jackssmirkingrevenge]

If I make a cast epoxy qev piston, and spring behind it, could I chamber fill and pilot from behind with like a blowgun or something simmer?

Pretty much what I did here using a schrader as a pilot.

[youtube][/youtube]

[1nxtmonster]

Yep, pretty much that. I'm making a pilot valve like this:

[youtube][/youtube]

[1nxtmonster]

Sorry for double post, but does anyone know a reason for a drastic power loss in a qev slide valve setup? Same pressure

[bravootome]

Sorry for double post, but does anyone know a reason for a drastic power loss in a rev slide valve setup? Same pressure

is the sound more a fss than a boom ?

[1nxtmonster]

Yeah, instead of a nice loud "CRACK" its more like" sssshhpow"

[jackssmirkingrevenge]

Yeah, instead of a nice loud "CRACK" its more like" sssshhpow"

Have you opened your QEV to see what state your piston is in? Did you lube it with WD40 or something similarly bad for rubber?

[1nxtmonster]

I opened the qev, and the piston is fine. I didn't lube it with anything bad, but some gunk had built up from lubing the slide valve. So i cleaned the qev out, cleaned the slide valve out, and removed a few cc's of dead space from my loading mech. In the process i broke something, so the epoxy is curing.

Well, the epoxy is cured enough that I took a few shots. Power is good, not sure if it was a problem with the qev, slide valve, or dead space in the loading mech.

**Edit** Under pressure, the slide valve doesn't want to move. The more pressure, the harder it is to move. I am using this slide valve:

41RHQmwGPBL._SL500_AA300_.jpg (10.19 KiB) Viewed 7496 times

Any ideas?

[bladeul2006]

thats how it works. look at my build http://www.spudfiles.com/pneumatic-cann ... 25393.html
basically the same idea on my pilot, just machined by me. At 400 psi it's fairly hard to pull it back. I use to lube it with silicon oil for a easier pull