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custom auto valve

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: psycix » Wed Jan 28, 2009 11:04 am

Wow! Nice!
I expected an easy "pop-pop-pop" to begin with but no, he just killed the CD cover with a RADADADA.


You should definitely work on a reliable feed mechanism.
Why did it go crazy at the start?


btw Your laz0rs are back! :D
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 28, 2009 12:04 pm

The magazine looks something like the attached diagram, and basically works on this principle

Since the one in the video is attached with tape and haemorrhages air like there's no tomorrow, the erratic behaviour is not surprising. I'm making a proper one now though, with the capacity for at least 30 pelletsand capable of being completely sealed. I'll see if I can get it to work as it is, if not some kind of blow-forward paddle/interrupter gear is in order, either way it's looking good :)
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Unread postAuthor: psycix » Wed Jan 28, 2009 12:41 pm

That is not a feed mechanism.
That is pushing pellets down a T piece.


jackssmirkingrevenge wrote:this principle
I wouldnt place my bets on that. If the spring strength is more powerful then the pressure, you'll get double (and triple and more) feeding.
Now you may say, the pressure is strong enough. But when the air is moving past at high speeds you know what happens: The effective pressure drops.


Shouldnt you go with spherical ammo? Easier to make.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 28, 2009 12:55 pm

psycix wrote:If the spring strength is more powerful then the pressure, you'll get double (and triple and more) feeding.
Now you may say, the pressure is strong enough. But when the air is moving past at high speeds you know what happens: The effective pressure drops.


Valid points, which is why I'm going to try it as it is tweaking the strength applied to the stack. If that doesn't work, I'll make an interrupter.

Shouldnt you go with spherical ammo? Easier to make.


If I had a good supply of 6mm steel ammo, or 5.5mm lead balls, this would definitely be the route to take, however I don't have these options so pellets it is, as 6mm airsoft BBs aren't the best for damage and damage is what we want :)
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Unread postAuthor: jackssmirkingrevenge » Sat Jan 31, 2009 12:07 pm

No I haven't let Landrover fever go to my head and forgotten about this :p

With the improved magazine, I did manage one perfect 6 round burst pop-pop-pop-pop-pop-pop, but sod's law, just as I was preparing another mag to film it, the valve stopped working :(

After doing some tests, it transpires that the piston isn't sealing well. Even if the air spring is pressurised to 150 psi, it still lets the 110 psi in the chamber leak. As it's sealed shut, not much chance of finding out what went wrong without wrecking it either.

Still, I now know for sure that the design works, so I have more than enough motivation to build another one :) this time I think I'll ditch the air spring and use a coil spring, that will be adjustable and removable along with the piston. I know you all by now are tired of staring at the same spot, but keep watching this space ;)
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Unread postAuthor: sputnick » Sat Jan 31, 2009 12:10 pm

Why not conform and use threaded stuff instead of epoxy this time? if not for just this next model so you can trouble shoot and take it apart untill everything is moron proof?

I know, Its JSR, if its not epoxy, its nothing, but just for this one so you dont have to keep building new ones please!
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Unread postAuthor: Sticky_Tape » Sat Jan 31, 2009 12:15 pm

Must have been cool to watch and another ''Thing to pattented and shown to airsoft and airgun manufaturers to make money''.
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Unread postAuthor: sputnick » Sat Jan 31, 2009 12:17 pm

Hey, that makes me wonder, JSR have you ever tryed to patent anything? some of your designs could be worth money no problem, I know this is an open sharing website, but still, you could make money off of some of your stuff...
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Unread postAuthor: jackssmirkingrevenge » Sat Jan 31, 2009 1:13 pm

sputnick wrote:Why not conform and use threaded stuff instead of epoxy this time?


HERESY!

I know, it's inconvenient, but while taxing on the soul it's a really cheap way to make things, once you have the mental strength to be able to start over.

JSR have you ever tryed to patent anything? some of your designs could be worth money no problem, I know this is an open sharing website, but still, you could make money off of some of your stuff...


It's very hard to have an idea that hasn't been thought of before, the subject of this thread for example is based on a safety valve design that's at least a century old. Besides, I don't really believe in holding on to my ideas and parting with them for financial gain, on the contrary the more my designs are copied that's the best recompense I can receive :)

There's also the liability issue, I've never made a launcher on commission or sold one to anyone, purely because of the legal issues. I've made a few silencers, sold for practically no profit, but that was completely above board.
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Unread postAuthor: SPG » Tue Feb 17, 2009 3:06 pm

Jack

I see you've been busy while I've been off in bike and scooter-land. Nice new design you've got here and what? it actually works?

One thought on a breech. You've talked about blow-back/forward breeches, which are gas powered. Why not just go for a straight linkage off your piston

Image

On the left hand side of your pic you've got a single piston with a pressurised "air-spring" on one side and your "chamber" on the other. If you had a twin piston set up with a rod between the two (have I lost you yet?) then the space between wouldn't be pressurised and you could easily take a rod off to work your breech.
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 17, 2009 7:56 pm

As a long time contributor to my quest I was wondering when you'd comment on this one :)

Interesting thought, as you might remember I had linked the pop-off piston and breech when playing with this idea but the tiny piston travel didn't make it practical.

Image

In the case of the subject of this thread however, the disproportionally large piston compared to the transfer port makes for a lot of travel as you can see in the first videos, which means that adding such a feature to the above design might just make it practical. Still on the drawing board ;)
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 01, 2009 2:29 pm

Introducing version 2.0 :)

Replaced the air spring with a coil spring, so the piston isn't 100% airtight but the (yes, psycix) threaded cap is so not a lot of air is wasted, and it's reasonably servicable ;) Seat and piston diameter are reduced compared to my previous prototype, we'll see how it goes tomorrow when it's fully hardened.
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Unread postAuthor: sniper hero » Wed Apr 01, 2009 3:40 pm

wow good work !

about the pellet magazine, why not buy flat headed pellets and stack them horizontally?
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Unread postAuthor: psycix » Wed Apr 01, 2009 4:53 pm

Good luck!

I have a feeling that it will work better without cap.
If you stop air from going out, the pressure on the back side of the piston will rise when air leaks past and especially if it moves back. Result: big force pushing the piston down.
If you are lucky, then this effect is beneficial and helps cycling in some way. If you are unlucky, well, it will not.



Join the threaded side... and then you will rule the empire of serviceability!
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Unread postAuthor: Sticky_Tape » Wed Apr 01, 2009 5:42 pm

Very nice looking valve jack lets see how it performs. Also how big is this compared to the last valve?
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