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New guy! Been searching around for info on a DIY airsoft sniper and I can see that this is the place!
Some back ground, I'm quite comfortable working with airsoft guns, gear boxes, barrels, hop ups ect. I'm also pretty versed in tanks, quick connects, valves ect. as I used to hot rod back in the day and I had a pretty sweet Nissan pick up with airbags.
Anyway, on to the good stuff!
I was considering using an old pump style paintball gun as the foundation of my sniper, which I want to use HPA or Co2. I also want to stay away from electrical solenoids / air valves. While I have a pretty good working knowledge of valves, I don't have an intimate knowledge of the various products out there.
I did manage to see this guys video and he mentions in the comments that he got his info here. Do you know what kind of valve he used? I like how he's got the trigger built right into it.
Here's a few other questions I came up with in my research...
Would Co2 not be a good choice for use with air valves? I have a feeling it may not be good with the internals.
If positive pressure is applied to the BBs as they are loaded into the gun, is it necessary to have a tappet to push the BB into the hop up?
If that's the case, I'd be fine with building that into a bolt action, as that was my idea to begin with. I just had more worries about getting the propellant to the back of the BB than anything.
What sort of valves would you recommend for a trigger like action? I'd like to stay away from blow guns and such. My goal with this is to make it look and function (as much as possible for a DIY gun anyway) like a regular airsoft gun as I'd like to be able to use it in a game.
Anyway, I think that's all I got right now. Many thanks in advance!
He is using a QEV and a 3 way valve with a bolt action system for loading BB's. There are tons of people here who use similar valve systems so you should look through the airsoft and pneumatic sections of the forum.[/url]
I found this manual 3 way valve. Would this work as a trigger for a gun?
http://www.sourcingmap.com/npt-12-ac241 ... 7AodHDgA6Q
Product Name Spring Return Air Valve
Type 2 Position 3 Way
Button Type Lever
Thread Size NPT 1/2"
Thread Diameter (Small) 5mm
Total Size 60 x 50 x 15mm /2.4'' x 2.0'' x 0.6''(L*W*T)
Body Size 42 x 32 x 12mm / 1.7" x 1.3" x 0.6"(L*W*T)
Handle Length 50mm / 2.0"
Color Silver Tone
Net Weight 170g
Package Content 1 x Spring Return Air Valve
2 position 3 way mechanical valve.
Mechanical valves are reversing valves controlled by external mechanical force. When the external force disappears, the valve will reset itself and reverse the direction.
Normally used to control the output signal of pneumatic systems.
Check out this thread for my experiences with the above: http://www.spudfiles.com/forums/semi-au ... 23626.html
That means it's pretty much "normally open". Have you thought about plumbing the valve in reverse? Does that work on this type of valve?
Here's a similar one for a few dollars more that can apparently be plumbed open or closed..
http://www.globalindustrial.com/p/pneum ... 7Aod4TwAcQ
Don't know if this might be relevant to you, but seeing as your going down the store-bought directional valves route, this link might hold some useful links for you to have a brief read, might help answer some of the questions you have, http://www.spudfiles.com/forums/directional-control-valves-3way-valves-and-stuff-like-that-t20438.html
As to your question, I think that valves, like what you have posted, can be put in either way into a system as they aren't poppet based.
By all means if you are feeling unsure about it then I'd go for the more expensive one to give peace of mind, but as far as my understanding goes, it would be okay to use the cheaper one and put it in reverse, I'm pretty certain people have done it in the past.
Actually, the one you linked to originally will probably.
The ones I bought only have two threaded ports, the third port is in the stem.
You can see the small holes in the brass bit. Obviously you can't thread into these.
cammyd32, thanks for the link! I already read through it, so I'm glad to know I was on the right track. They do work as I thought, so I think I can anticipate that they'd work for my application.
Sadly, yes, I'm going to be a gimp and use off the shelf parts. I'm basically taking a bunch of parts and cramming them together into something new.
Doing proper machining is just something I don't have time or money for But at the same time, I'd like this gun to be compatible with paintball / airsoft parts as I want to field it, so necessity is sort of the mother of this invention, so to speak Aside from the raw (and beginner's) challenge that is. I've already rebuilt a P90 and enjoyed the experience so I'm looking forward to doing this.
Jack, I see what you mean about the valve. That's a bummer!
Can someone tell me what the QEV and chamber that you guys use is for? Is there a performance boost or is it part of a semi auto system?
I was anticipating just running the line from the tank > 3 way > cylinder head > nozzle > hop up. Since I'm doing a bolt action setup, do I need more than that?
The one you linked to first is different though - note it has two "R" ports, one of these can be blocked off and you can feed into the other. It should therefore work as a trigger.
Not sure if I understand the question. A detailed explanation of how the system works can be found here: http://www.spudfiles.com/forums/viewtop ... tml#367090
Ah... you want to use the three way valve as a direct trigger?
Normally they are used to pilot the QEV which would be the main valve, as explained above. For airsoft though this might be overkill, especially if you're using high pressure. Yeah, this could work...
Not the way that wyz went about it in the example you linked to though: http://www.spudfiles.com/forums/buildin ... 24498.html
I need to stay within 500-600 FPS. The operating threshold of the valve is 120 PSI.
In a the video you posted of the low cost, semi auto trigger, you said you were getting near that with roughly that amount of PSI. That's why I was wondering if I needed the QEV and chamber.
Thanks to the many details posts you guys have here, I understand how it works, although I'm not quite sure when, how or why to use one.
I was leaning towards no as you were saying for airsoft. Since all an airsoft gun does is compress air in a cylinder and then shoot it out a small tube.
I was thinking of going with a HPA Ninja tank and regulating it down to 120.
That is quite an understatement, pressures in that little tube can reach upwards of 500 psi in the more expensive rifles, of course that pressure only acts for a fraction of a second, but still, no small amount. It takes quite a bit of energy to propel a 0.2 gram pellet to 600fps.
The reason why many people use QEV's to boost power is because we are very much about increasing flow here on the forum, QEV's decrease the opening time of the valve and have very efficient flow from the chamber to the barrel, if you have shite flow and a long opening time, it makes no difference of the amount of pressure you have, performance will always be shite too*, for example: if the gas just comes dribbling out from the triggered valve, then similarly the gas will just dribble into the barrel, and consequently disperse through blowby before is has time to exert any amount of force of the pellet.
So it would also give more consistency from shot to shot? That's something I'm concerned about as well.
Yes, it will be more consistent. A manual valve's performance depends on user's precision, which can vary from shot to shot. When you pilot a QEV though, the valve will operate much more consistently because you aren't directly operating the valve. Although consistency isn't really the main benefit of switching to a QEV (power and efficiency are), it certainly exists.
If you want real consistency, think about a hammer valve. A bit more labour intensive but an interesting project, wyz also has a good example:
http://www.spudfiles.com/forums/hammer- ... 23202.html
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