1st Pneumatic Rifle

[gsw2]

Hi everyone 1st post (although I've stalked this forum for a while),
I have previously made a PVC gun which simply consisted of a chamber, car tire valve, ball valve and barrel. It's bulky, hard to fire and plain boring. It's school holidays now in Australia and I'm wishing to make a new rifle.
I've used the search (and google), read through countless threads and posts but can't find an explanation on how to do this. The thing that confuses me the most is the QEV or equivalent trigger device. How do I use it and incorporate it into my build? I wish to make it out of a metal (copper?). I probably sound extremely nooby. Any help is appreciated greatly.

Thanks!

[Gun Freak]

QEVs are manufactured piston valves and it is probably the easiest way to go. They are very powerful too. But if you want something bigger than 3/4", you need to build a piston valve. There are plenty of tutorials you can use to help you understand how they work.

[Crna Legija]

i don't quite get what you what help with, this is how piston valve, the second one is how QEVs work.

[gsw2]

A QEV sounds like the best bet if its the easiest option. Has someone got a basic diagram? I just need something to understand whats going on inside.
Thanks for your super fast replys!!

[Gun Freak]

This was in the wiki...

[Crna Legija]

A QEV sounds like the best bet if its the easiest option. Has someone got a basic diagram? I just need something to understand whats going on inside.
Thanks for your super fast replys!!

did you look at the link in my post? the second one is how they work.

[gsw2]

Thanks a lot both diagrams explained everything perfectly; air goes in pushes QEV closed and blocks barrel - airs released at exhaust point creates pressure sucking the QEV open allowing air out of the barrel. Correct me please if I have the wrong idea.

One last thing so I can stop being annoying. For the exhaust point what should I use that will have a trigger and not be to complicated?
I just read about slide valves that look extremely easy to incorporate, are they used for exhaust valves?

[Gippeto]

One last thing so I can stop being annoying. For the exhaust point what should I use that will have a trigger and not be to complicated?
I just read about slide valves that look extremely easy to incorporate, are they used for exhaust valves?

The lowly blowgun has worked for many...myself included.

Slide valve as trigger has also been done.

http://www.spudfiles.com/forums/heal-32 ... 11453.html

[gsw2]

Blowgun sounds perfect!!
http://www.spudfiles.com/forums/blowgun ... t7481.html
Looks good as well.
I'm practically sorted now, thanks for all your help!

EDIT: I've got a small problem. I was showing my dad what to do and he pointed out the air canister that all of the rifles have on this site. Is it necessary or can I simply use pumped air? and is normal copper ok for the chamber? Will it hold 100psi?

[Gun Freak]

What air cannister? Copper will be a great chamber, you could safely put 6 to 8 hundred psi in small diameter pipes.

[Gippeto]

You're using a qev, correct? If so, they commonly come equipped with pipe thread. Why not use a piece of galvanized or black iron pipe for the pressure chamber and simply thread it together?

No sweating copper necessary. Although I will admit, it's a VERY useful skill to have.

[cannon monkey]

Sorry to thread jack but. What size home made piston valve will give the same performance power as a 3/4 qev??? Thanks and sorry for small thread jack

[Gun Freak]

Could have put this in the short question topic but I'd say a 3/4" valve lol.

[cannon monkey]

Wops so 3/4 PVC piston will give same performance as 3/4 qev

[jackssmirkingrevenge]

Wops so 3/4 PVC piston will give same performance as 3/4 qev

A QEV is a piston valve, it works in exactly the same way.

So, matching its performance depends on how well you can optimise your own piston valve, with a lightweight, low friction piston that is tight fitting, good flow, low pilot volume etc.