SpudFiles

Can blowguns and QEV's take 400psi of pressure

How long is a piece of string?... Depends what blowguns and QEV's they are because there are types for all applications. I would say confidently that there are such blowguns and QE valves that handle those pressures.

QEV's, are that valves that protect against overpressure ?

no, the one you're talking about are pop-off valves.... QEV are like modded sprinkler valves, but they're made from aluminium, and don't need modification.


@L.J.R : You wan't to make a semi auto replica?
what caliber do you want it to be?
What projectile will you use when finished?
consider the weight of the final product....

Making the body of the "weapon" isn't difficult here, you just have some pictures, and if you are gifted with the realisation capabilities, then the body shouldn't be a serious problem.
The real problem comes from choosing a valve, choosing a reload mechanism...
I have some ideas for you:
First of all, the trigger, must be relied to an exhaust with a strong metal piece and a spring so that the trigger comes back in position when you stop pressing.
The CO2 bottle could be relied to a hose, which would go through the stock, and connected to the chamber. There would be a nozzle, like in airsoft replicas. the moment you press the trigger, stops the co2 flow from the bottle, makes the nozzle come back 1 cm to let out the BB in front of it, then a spring could violently make the nozzle come back in possition (engaged in the barrel) and by the way, open the exhaust behing the chamber, and let the air out.
so that you have 5 steps.
1 ) cut the flow from the co2 bottle
2 ) slide the nozzle backwards
3 ) slide the nozzle forwards
4 ) exhaust + releasing the co2 in the barrel via the nozzle.
5 ) release the trigger = close the exhaust, open the flow from the bottle.

I don't know how to make diagrams, so sorry, cuz i think my concept could work great. this could all be electronic, with multiple position connectors...
Or mecanic, with metals pieces, relied to springs and other metal pieces...

hope it helped...

EDIT: i came up with the idea of making a paint concept...it's my first so don't exept something awesome, just the basic....

Thanks CpTn_lAw thats really help full to bad you can't draw diagrams because that sounds good but I missed a couple of things I'll re-read it a couple of times.

what caliber do you want it to be?
What projectile will you use when finished?
consider the weight of the final product....

Well I was going to have the barrel .22 but then I thought I might have it .177 because I have a cheap air rifle barrel already though I don't think it's rifled. so I might stick to .22. For the ammo I wanted something about 1.25cm long with a rounded point but thats going to be hard to keep consistent. The weight doesn't really bother me but i'll try to keep the weight reasonable.

This is a diagram I drew in paint its not perfect and has alot of problems but it shows the main concepts

The light green is the room I got to play with the exhaust, the rest is pretty much self explanatory except maybe for the bolt system.

i'm glad i can help!!

Okay dude, so you want it semi-auto. That's where it becomes expensive. I'm sort of in the same boat as you although I'm replicating an m107 .50 cal rifle. It's very similar to clides semi auto (search) but with a few mods to the piston, slide valve and loading mech and a built in hpa source. I fiddled with your m16 just incorporating clide's semi-auto design into it. Its fairly simple (you probably can't see the detail too well because it was saved as a jpeg...) although the parts will have to be machined out of metal. And if you were really keen on building it, it shouldn't seem too much work. (Check twice, machine once...) I'm using a 68ci 4500psi hpa tank with a 40cm remote stainless mesh hose, a few fittings with a 0-800psi inline stabilizer as the onboard hpa setup, and if you play around with it for a while you'll figure out a way to fit it in your stock. (Maybe not the 68ci tank, there are smaller ones though) You'll also need a safety valve and some means of connecting the slide valve to a trigger. I was pondering on using a bicycle brake line to solve that. Just remember semi auto's aren't a quick, easy or cheap project and hence why not many have built one. All the best

Thats another good idea but I need access to a lathe, Yeah I know semi-auto is going to be hard and expensive but i'm coming to the conclusion that enjoy building the gun more than firing it.

I had another look at CpTn_lAw's design and the only thing I don't like about it is the dead spac behind the magazine i know that could be fixed by having thepiston in a T but I don't think I would be able to fit it inside the gun and keep the barrel where it's supposed to be. one thing I like about it are the electronic iterupptors i'm gathering that they are some type of electronic valve or electromagnets "please explain".

The jolly rogers's Idea gave me some good Ideas but the only thing I don't like about that is the magazine system, I know I can use a different one bet anyway.

here is my latest design
this is the jpeg

this is the bmap

I'll go throught the operation quickly
1. squeeze trigger.
2. small electronic valve opens.
3.slide valve bolt is pushed forward quickly by the air from the chamber.
4.slide valve opens.
5.piston exhausts.
6.Projectile fires
7.chamber losses pressure.
8.Spring pushes slide valve closed.
9. electronic valve closes.
10. Then repeats.

I haven't quite figured out how the bolt will be operated yet but you can see the concept I plan to use in the picture"I hope".

EDIT damn photobucket only loads jpegs the bmap file was alot better.

Dude thats a good idea! Complex but it would work. I didn't look into the loading system as it would be fairly easy anyway (hence why I didn't really emphasize in my sketch) but your firing concept is quite good. Of course if it could be done just as effectively with a simple connection between the trigger and slide valve (the trigger pressure would depend on the springs holding the slide valve closed) it would make it alot easier (kiss). Plus I think he wants one that is built for high pressure (300 - 400psi, i think unless I have the wrong thread) which means he will be extremely lucky to find a suitable solenoid valve, let alone be able to afford it.. But apart from that I like your design alot.

I know that there's no way I'll find a soleniod valve good enough let alone small enough but it's an idea. Although CpTn_lAw proposed that his idea could be all electric and it involved turning off a direct Co2 source, maybe the exhaust will just have to be some sort of QE valve.

No QEV I've heard of can take that much pressure, but what do I know...

I have run out of ideas for the exhaust valve, I am only left with either a hammer valve or a slide valve. I dont think the slide valve would work to well because of high pressures and I would need very tight o-rings making it harder to open. That leaves the hammer valve I can't think of any good ideas for that except maybe having it very small so that it doesn't take much force to open but then the valve opens slower etc. hmmn I'm stuck anyone else got any ideas, I don't want to use a blowgun but thats the only thing that seems practicall at the moment, I might go and pull a blowgun apart and see how they work.

EDIT 16:21
well thats something i didn't know blowguns basically use hammer valves well that was a wast of time.

come on someone has to give me at least a small idea for me to work on.

Slide valves can hold alot of pressure dude, they use them on paintball guns to disconect the line from the source without losing air. Seacrh paintball slide check valves. Thats what I'd be using.