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burst disk cartridge idea

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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burst disk cartridge idea

Unread postAuthor: jackssmirkingrevenge » Wed Sep 19, 2007 4:31 am

Anyone with machine-shop access care to make me one?

where's the puppy-dog eyes smiley when you need it :roll:

After the testing of my 6mm burst disk prototype exceeded my power expectations, it's clear that the potential for this idea is valid. I'm going to look into the possibility of having the body of this cartridge design machined for me, if it isn't too prohibitive then expect further tests :)
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Unread postAuthor: MrCrowley » Wed Sep 19, 2007 4:45 am

I think I thought of a similar idea but for a airsoft grenade, correct me if i'm wrong but its based on a similar principle, is it not?
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This is quite old and pimpmann pointed out some flaws with it and I never got round to testing it.
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 19, 2007 5:12 am

It's a similar concept in that a spring-loaded sharpened tube is used to rupture the burst disk, what sort of flaws did pimpman predict?
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Unread postAuthor: MrCrowley » Wed Sep 19, 2007 5:15 am

I can't remember, I think it's in my MSN message history, i'll check.

Edit: Damn it was on my old computer.
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 19, 2007 5:23 am

I see no reason why my design wouldn't work - the question is, how much force will the bolt have to place when hitting the cartridge to rupture the disk? If this figure is too excessive, then the cart won't have enough energy to recock the bolt and you'd have to cycle the action manually.
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Unread postAuthor: MrCrowley » Wed Sep 19, 2007 5:33 am

I doubt there's much flaw with your idea, more mine. I don't see any reason why it shouldn't work.
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Unread postAuthor: Redcoat » Wed Sep 19, 2007 5:33 am

Not a bad Idea Jack, If i have the time i may try and scab some time in my Industrial Tech Class to machine some metal so i may be able to make one over a long period, but right now I'm scabbing time in Tech to make my Piston Valve, so yeah.


Happy Spuddin'
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Unread postAuthor: mega_swordman » Wed Sep 19, 2007 5:40 am

Jack, i am afraid I cannot quite understand your concept.
However, I do have an Idea of my own, If the volume of the container you have is reduced, the pressure will rise yes? So therefore, if you made a device that compressed the volume of your chamber, then the pressure would rise and rupture the bust disk. I will try getting a diagram up in a bit to better represent my idea.
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Unread postAuthor: MrCrowley » Wed Sep 19, 2007 5:40 am

jackssmirkingrevenge wrote:I see no reason why my design wouldn't work - the question is, how much force will the bolt have to place when hitting the cartridge to rupture the disk? If this figure is too excessive, then the cart won't have enough energy to recock the bolt and you'd have to cycle the action manually.


I doubt much at all, if the barrel is metal and sharpened enough
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 19, 2007 5:50 am

If i have the time i may try and scab some time in my Industrial Tech Class to machine some metal so i may be able to make one over a long period, but right now I'm scabbing time in Tech to make my Piston Valve, so yeah.


I have a friend in the UK who has machined silencer adapters for me in the past for a reasonable fee, I'll draw up exact plans and see what he quotes me for.

Jack, I am afraid I cannot quite understand your concept.


It's fairly straightforwards, spring loaded bolt smacks the base of the cartridge, which forces the disc against the sharpened end of the barrel, thus bursting it. Aire pressure is released, pushing the projectile out of the barrel and the cartridge back out of the breech.

If the volume of the container you have is reduced, the pressure will rise yes? So therefore, if you made a device that compressed the volume of your chamber, then the pressure would rise and rupture the bust disk.


The cartridge is already going to be at several hundred psi, the extra energy required to compress it further in one go would make a launcher for such a device impractical.
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Unread postAuthor: mega_swordman » Wed Sep 19, 2007 9:50 am

Thanks Jack, I get it now. Would my idea work under lower pressures? I can understand at a couple hundred it not working, but what about in the high double digits?
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 19, 2007 10:06 am

mega_swordman wrote:Would my idea work under lower pressures? I can understand at a couple hundred it not working, but what about in the high double digits?


It depends on how you intend to go about increasing the pressure, a diagram of how you would intend to do it would be helpful but I don't see a way of achieving this without using a disproportionate amount of force - unless of course you're straining the disk to within a few psi of bursting, which isn't a practical or safe proposition.
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Unread postAuthor: psycix » Wed Sep 19, 2007 3:52 pm

If you want to rupture the disk and the end of the barrel isnt sharp enough, attach a few needles or a small knife to it :)
Bye bye burst disk :)
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Unread postAuthor: FeLeX » Fri Sep 21, 2007 7:46 am

Wouldnt you need some kind of a stopper behind the bb to prevent the burst disk pushing it back?
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Unread postAuthor: jackssmirkingrevenge » Fri Sep 21, 2007 10:13 am

The disk will be bulged forward anyway, but a bit of paper wadding should be enough to keep it in place.
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