I HAS FULL AUTO :D

[Sticky_Tape]

Haha I agree we need a pic of the setup also LAZOR sounds! I like the dammage it does to that piece of metal nice holes, it doesn't look like it has been chewed by a metal goat

[SpudsMcGee]

Instead of making a marble gun, why not try a paintball gun... Sure it wouldn't be as destructive be it would have more colorful results.

[Gippeto]

The destination is better appreciated after an extended journey, eh Jack.

Well done, congrats!

[Fnord]

Ha, that's so awesome I'm gonna have to try it.
but with unregged CO2 and a beefy spring or something.

You should add chrony stuff to the original post. Great job.

[tomthebomb137]

oh boy sounds dangerous
careful with unreged CO2, and if your firing rapidly, its going to freeze up very fast, just something to look out for

[inonickname]

oh boy sounds dangerous
careful with unreged CO2, and if your firing rapidly, its going to freeze up very fast, just something to look out for

Depends. Probably, but if he plays his cards right he may be able to use friction heating and other factors to prevent this. Good lcuk

[mega_swordman]

Interesting, but I couldn't help but to notice an odd fact. The sound of the piston actuating in this video sounds much more like the, for lack of a better term, sloppy opening of the original pop-off valve, not the clean and crisp sound that delighted my ears yesterday. Why is this? Is it just an odd audio problem caused by the addition of the barrel, or is something more sinister occurring here?

[tomthebomb137]

that would be very interesting if he could pull it off, to get that much heat, but if your having trouble, look for a paintball HPA tank, they began using them to counter that very problem on high end fast guns

[jackssmirkingrevenge]

Thanks for all the comments guys

does the spring really seal it with a continuous stream of air coming in? I'm sort of surprised by that.... would've thought it would just stay open the whole time..

Does it have anything to do with the different diameters of the two? (piston tube and firing chamber)

That's the point of the design. While it's just covering the piston seat, the spring is enough to hold the air in until pop-off pressure is reached. Once that happens and the piston opens slightly, the whole surface are of the piston is exposed to the pressure and the spring can't handle it, hence the POP!

looks like JSR is my jesus

Go forth my son, and blast ye holes in stuff at reasonably economical rates of fire

This Has inspired me to attempt this.

To be honest generating interest in this type of valve is personally as big an achievement as actually getting it to work

Any reason you didn't make it fire as fast as it can?

In virtual gibberish, DAKKADAKKA PWNS BRAAAAP!!!1!!11

*ahem*

Although i have one question.... Whats the strength of the spring your using? I thought you had really hit the jackpot when you used the air pressure spring, but this seems to work far better.

The spring is compressed to about 10lbs, it came from my scrap box, no idea what it was originally. I don't think it works better or worse than the air spring apart from the fact that less friction seems to make it open faster. Also, it's more reliable in the sense that once you set it to the right compression, you don't have to worry about it losing air and the spring changing.

How does that magazine work for you? Any double feeds..things like that?

Very well as you can see, props to Spudinatorfor coming up with it in the first place.

Instead of making a marble gun, why not try a paintball gun... Sure it wouldn't be as destructive be it would have more colorful results.

.. so what's the point?

The destination is better appreciated after an extended journey, eh Jack.

No kidding

The sound of the piston actuating in this video sounds much more like the, for lack of a better term, sloppy opening of the original pop-off valve, not the clean and crisp sound that delighted my ears yesterday. Why is this? Is it just an odd audio problem caused by the addition of the barrel, or is something more sinister occurring here?

The barrel is obviously acting as a "suppressor" as the air is expending energy before exiting the barrel, unlike the unmounted valve with the air going directly to the atmosphere. Also there's the not inconsiderable noise of the pellets hitting the plate.

I'm really glad with the interest this has generated, I don't want to say I'm an authority on this type of valve but if I can help anyone with their own projects, go ahead and ask. I think POLAND_SPUD's idea of inverting a QEV has some merit for those who want to cut down on fabrication.

For those of you who wanted pics of the setup, here's an "exploded view" of the valve and magazine units:

[SPG]

Jack, Jack don't stray to the dark side of larger calibres, you know you want to stick under 6mm, so the only solution is you have to go up in pressure, I know high pressure = higher chance of failure and consequent damage to body parts but it's worth the risk isn't it?

Anyway I would have thought you could easily build in a fail point so that you knew that if it was going to fail it'd fail in a "safe" way. After all you've got low flow in, so as long as the failure area allows your gas out faster than it can go in, you should be fine.

It's crying out for CO2 though even something as simple as a 12 gram tire inflator, than should keep the flow down a bit.

[django]

Wow!!!, Well done mate it was a long haul but You've done what most of us on here have been trying to get up and running for years! 8) now if I only understood how it works I could try build one?.Also cant understand how those pellets are actually feeding in instead of just holding inplace and air rushing past the pellet?. I'll have to read over this thread again tomorrow when Im sober ...............

[jackssmirkingrevenge]

Jack, Jack don't stray to the dark side of larger calibres, you know you want to stick under 6mm, so the only solution is you have to go up in pressure, I know high pressure = higher chance of failure and consequent damage to body parts but it's worth the risk isn't it?

You're right, I think I should stick with small calibres.

Did some more testing this morning, I have some chrony results

For single shots with 0.25g airsoft BBs, velocity was between 550 and 600 fps - skirmishing for sadists, surely.

With 1 gram lead pellets, it averaged around 370 feet per second, a healthy 5 ft/lbs and significantly better performance than I was getting with the first version of this valve - clearly less friction is a better idea.

Made some more vidoes too, here's a transparent chocolate box cover:

[youtube][/youtube]

I then took out a little toy digger that I had been wanting to destroy for ages. I extended the magazine in a ghetto manner to fit 30 pellets but as everything was held together with tape it was getting stuck so for the last couple of videos I stuck to the 10 round magazine.

[youtube][/youtube]


[youtube][/youtube]


[youtube][/youtube]


[youtube][/youtube]


[youtube][/youtube]

Here's what was left of it, still generally recognisable but now significantly better ventilated

[psycix]

Very nice!
Your loading mechanism is so simple, I am surprised it works.
Does it load perfectly?
Every vid when it stops feeding, is it simply empty or is it just jamming? I also noticed that it seems like it doesnt like high ROF, in the first vid you seem to have it jam every burst.
Though its simplicity surely makes up for the reliability.
Great job!

[sniper hero]

ah and it was such a nice toy

good work ! vids are always welcome 8)

[jackssmirkingrevenge]

Very nice!

Go on, your turn!

I have to say I prefer this to QEV+popoff, for two main reasons. First of all, there's no wasted air - it's all going out of the barrel, unlike a pilot valve. Secondly, you know that when it fires, the chamber is up to maximum pressure. I have a feeling that the QEV fires before the chamber has had time to fill completely.

Your loading mechanism is so simple, I am surprised it works.
Does it load perfectly?

Yes, as you can tell from the first videos, one shot per air "pulse", no double feeds and no misses.

Every vid when it stops feeding, is it simply empty or is it just jamming? I also noticed that it seems like it doesnt like high ROF, in the first vid you seem to have it jam every burst.

Ignore the first three vids, those were with a magazine extension taped on in an extremely ghetto manner, the pellets weren't going in smoothly. I might make a proper 30 round mag later

ah and it was such a nice toy

What the hell did you expect me to do, donate to an orphanage?

I was curious to see if a weaker spring let the piston open more and improved performance, so did some chrony tests with less spring compression in the meantime, pellets were doing around 320 feet per second. Clearly MOAR SPRING = MOAR POWER!