Stainless steel Hydrogen cannon

Miniature guns are novelty custom, unique, and sometime downright crude! Common construction materials often include pill bottles or pens. Show us your work!
jon_89
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Fri Apr 25, 2008 11:35 pm

Looks good. What is your eletrolacis setup?
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jook13
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Fri Apr 25, 2008 11:37 pm

I think its a snazzy little gun. I also would love to see the electrolysis setup.
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xrcv
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Sat Apr 26, 2008 1:37 am

Oook , so here's the electrolyser:
Electrolyser Diagram
Electrolyser1
Electrolyser2
Electrolyser3


The whole thing is less than a foot high.For electrolyte i use baking soda. When i run it at 12v it puts out about 100cc/minute(haven't measured it though, just think so). There are a couple ways i connect it to the gun. The first is directly, which sometimes makes the rubber cork pop out(should fix that).The second is feeding the h2/o2 mix into a syringe and then injecting the syringe into the gun. :P
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Sat Apr 26, 2008 1:48 am

xrcv wrote:Oook , so here's the electrolyser:
Electrolyser Diagram
Electrolyser1
Electrolyser2
Electrolyser3


The whole thing is less than a foot high.For electrolyte i use baking soda. When i run it at 12v it puts out about 100cc/minute(haven't measured it though, just think so). There are a couple ways i connect it to the gun. The first is directly, which sometimes makes the rubber cork pop out(should fix that).The second is feeding the h2/o2 mix into a syringe and then injecting the syringe into the gun. :P
Thanyou xrcv, now a video please. :wink:
jon_89
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Sat Apr 26, 2008 2:20 am

how do you know you have enough? is hydrogen safe to use in pvc or is it best to use metal? can you explain the electrolocis machine more.
xrcv
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Sat Apr 26, 2008 2:27 am

jon_89 wrote:how do you know you have enough? is hydrogen safe to use in pvc or is it best to use metal? can you explain the electrolocis machine more.
1.A 40 sec run of the electrolyser is enough to fill the chamber.

2.The power of hydrogen is highly overrated and i think there won't be any problem using it with pvc, provided the chamber is small.As i said i use stainless steel, simply because i have easy access to tubes and a WIG(inert gas welding) machine.

3.I think the diagram is self-explainatory
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psycix
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Sat Apr 26, 2008 5:25 am

Using H2/O2 as fuel in a PVC chamber is not safe.
H2/O2 mixtures produce not much more heat then propane, but it does produce a shockwave because it burns way faster.
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jon_89
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Sun Apr 27, 2008 12:12 am

So will propane or h2/o2 give me more power? I ask because I see several ideas.
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Lentamentalisk
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Sun Apr 27, 2008 12:54 am

jon_89 wrote:So will propane or h2/o2 give me more power?
Not necessarily. H<sub>2</sub> and O<sub>2</sub> burn 8x (i think) as fast as propane, but I do not know about the power ratio.
Because it only creates water, as opposed to CO<sub>2</sub> and water, it will have a much higher speed of sound, so for hybrids going for supersonic, it is a better choice.
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psycix
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Mon Apr 28, 2008 5:52 am

It depends what you define as power.
The velocity that the projectile gains is caused by pressure.
Pressure is caused by heat.
Hydrogen does not produce much more heat then propane.
However, the oxygen allows for more fuel to be put in.
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CpTn_lAw
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Mon Apr 28, 2008 6:26 am

i'd say hydrogen is useful with light projectiles. If you've already put a balloon filled with H2/O2 over a flame, you probably have lost your hearing :P and you've probably seen that it doesn't "deflagrate" it detonates. The pressure spike happens much faster than with propane or butane. So even if the pressure created isn't THAT elevated, it causes the material to withstand a lot more stress.
Hydrogen is noisy, and clean...i personally think it's enough to make it fun to use when done safely :D
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JDP12
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Mon Apr 28, 2008 8:51 am

yea it would be fun... but the whole detonation thing could be dangerous. I was also going to make a mini out of stainless, but the 20 dollar fittings sort of turned me off of it..
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xrcv
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Mon Apr 28, 2008 11:52 am

Yep, the thing with light projectiles is totally true. A few times i tried shooting a long drill bit(bout 10 grams i guess). It didn't even come out of the barrel. Light projecticles like small nails and ball-bearings work fine though. And yes, stainless steel is expensive. I get it for cheap or free though. If anyone needs anything pm me. :).
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Ragnarok
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Mon Apr 28, 2008 1:55 pm

Not to be a killjoy - it's a lovely cannon... but you should be made aware of hydrogen embrittlement.
Many metals, but most notably steels, are severely weakened by contact with high(er) concentrations of hydrogen, as hydrogen diffuses into the metal, and forms tiny pockets of high pressures within minuscule cavities.

I would have no qualms about using it with propane fuelling, but hydrogen fuelling is not such a wise move.
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xrcv
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Mon Apr 28, 2008 2:01 pm

Not to be a killjoy - it's a lovely cannon... but you should be made aware of hydrogen embrittlement.
Many metals, but most notably steels, are severely weakened by contact with high(er) concentrations of hydrogen, as hydrogen diffuses into the metal, and forms tiny pockets of high pressures within minuscule cavities.

I would have no qualms about using it with propane fuelling, but hydrogen fuelling is not such a wise move.
In theory yes, I've heard that. In practice I've worked at a company which manufactured s.s hydrogen storage chambers filled with nickel-based alloy, some of them working @ 40 bar and more filled with pure hydrogen. No problem whatsoever.
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