QEV valves.

[Scottaiii]

Hey all

Been a long time since i've been on spudfiles, my old user name was Thursto, or Rapidfire i cant remember.

But anyways i wanted to start over so i decided to make a new account.

I've recently stumbled across an old rifle stock and have decided to make a BB gun out of it. If you don't remember, I'm from Australia which brings me to my next point.

Where can i buy a small QEV? It doesn't matter if its overseas, ill just have to cop the postage, money is not an issue.

Using this stock, i wanted to have an under-over construction, all metal BB Rifle. Using a QEV as the main valve. Simple but do-able.

I'll have a 6mm barrel approximently 500mm in length, and a 3/4" metal chamber, about 200mm long, but i plan to use high pressure.

Thanks for any help or suggestions you May have.

- Scott.

[jackssmirkingrevenge]

Welcome back

Why not make a coaxial?

[Scottaiii]

I don't know really, i'm a bit on the lazy side when it comes to making the valves. I tried making a piston cannon before and that just failed. I'm tempted now that i just looked at that link, ill have to have a try.

Theres a coaxial explanation on here somewhere isnt there?

But i'd still like to know where i could find a valve. I tried ebay, ill give amazon a go.

Thanks Jack.

[tghhs]

hey scottaiii, yeah i'm in aus too.

i can't remember where i got this link from, maby on a thread here unsure anyway it was in my favourits hope it helps

http://www.bellpro.net/xcart_program/home.php?cat=268

argh i've looked around at a few other websites can't find then atm if i do i'll edit my post to include them. hope u have more luck than me.

[jmadden91]

Yeh bellpro's great, they have a 40% discount at the moment to so they are cheap as. It comes off when you put it in your basket. Shipping is cheap to im going to pick one up soon

[Scottaiii]

Hey thanks for the link, they look different, almost better. Do they work the same as the one's you see on here? I'm guessing the exhaust port cant be seen in the photo?

Thanks.

[jackssmirkingrevenge]

I'm guessing the exhaust port cant be seen in the photo?

Correct. But at those prices, seriously, you can make a much better coaxial piston valve with very little effort. Drop a PM to jook13, I'm sure he'll be happy to give you some pointers

[Scottaiii]

What would be the performence differences? I'd get a 1/2" QEV that way it'd have more flow. I'm still going to give the Coaxial a go.

Whats a good face to use on the piston for a good seal? The last face i used did not seal on the barrel so i gave up.

[tghhs]

argh well, i'm not sure what u plan on making the piston out of. But JSR has a lot of knowlage on epoxy... helped me out a few times. and as a sealing face for that piston it's common practice here to use neopreen (sorry about spelling)

I'll have a 6mm barrel approximently 500mm in length, and a 3/4" metal chamber, about 200mm long, but i plan to use high pressure.

yeah, well i use 1/8 inch thick for my pistons, but have only tested with 100psi so i can't help out with the high pressuse part that well.

have you thought about ur pilot valve? i got a brass 1/4 inch ball valve for a water tap at bunnings, though i duno about the threads on it i guess BSP but could be severly wrong

ohh and this is another website i found. Use ful for me as it's on my way to school-ish. but i got no idea what state u in so could be useless ...

EDIT: ohh and getting a good seal, i read around here somewhere a good technique. you put black marker on ur barrel (when all finished up and built) and u put fine sand paper on the end of ur piston, with double sided tape. now u've done that pop it in the housing and twist away unitl all blask marker is gone. Used it before works well.

[Scottaiii]

Ah right well ill do a bit more research and head on down to bunnings and get some parts, and i live in SA, what about yourself? Yeh i use blow guns, and 1/4 taps. Ill find something.

Yeh ive seen the threads on the expoxy castings. Also if i built a coaxial how big do i need the equalization holes?

Thanks.

[jackssmirkingrevenge]

Inner tube from heavy duty tyres (like trucks) is a good sealing material. Unless you're making a piston with o-rings don't bother with equalisation holes, enough air will leak around the piston.

[tghhs]

yeah sounds good to me mm i'm in Vic, east of melbourne, dandenong ranges.

there's probaly someone with more experience than me to answer this but i'f ur not using o-rings u want the tight fit possible that will still allow u to actuate it with lungs, well thats what i go by, any tighter and i find the opening of the valve is slower then i'd like.

np

[inonickname]

Just go to clark rubber and buy some non compressible neoprene rubber, you can buy it in sheet, strips..whatever.

I got my QEV from bellpro, and it's fine.

[tghhs]

yea clark rubber is where i got my neoprene*, they have all sorts od thickness to

[Spooky]

Hi all,

I recently decided on and bought the pieces for my first pneumatic based on what I've learned from lurking here on this great forum.

I have a question about my QEV. I'm hoping that it will be simple for many of you and someone will take the time to help me out. I don't mean to hijack the original thread, I just thought this would be better than making a new one.

The QEV in question is 3/4" and of the same designed as the one used in 'Copperhead Prime' (they look identical).

The problem I am having is when I tried to test the QEV I couldn't get air to flow through "P". In my understanding the air should enter "P" and exit "A". I'd just been testing the valve by blowing down it, when that didn't work I attached a small section of tube with a Schroder in an endstop and pumped it.

This didn't get me flow through the valve either, the pressure just built up, although I know I did have leaks with this set up. I didn't solder or seal my fittings as I only have the parts I need for my build, and didn't want to waste them testing. At the same time I don't want to assemble my build around a possible faulty valve.

Does this type of valve just need to have more pressure applied to it for it to work, am I using it wrong, or could it be faulty. I hope I have managed to get what I am trying to say across, and that it doesn't sound too stupid.

Many thanks

Spook