carbide cannon
Posted: Sun Jan 27, 2008 12:32 pm
i was just wndering if any1 has ever mad a carbide cannon? i first saw it in a book caled backyard ballistics. wikapedia explains how it works.http://en.wikipedia.org/wiki/Carbide_Cannon
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Posted: Sun Jan 27, 2008 1:34 pm
It's just a simple combustion gun that uses acetylene gas produced by the reaction of calcium carbide with water. The one described in backyard ballistics is not a good design: it uses parts that can't take much pressure, so you can't put ammo in it, it's just a noisemaker.
Posted: Sun Jan 27, 2008 1:47 pm
Hey, that was the book that got me into spudding! Their carbide cannon is probably not a very good one to use, it has DWV parts, and the design has some flaws, but I would think that the idea would work if you made a good enough design. A carbide cannon would also have a cool muzzle flash 
Posted: Sun Jan 27, 2008 2:40 pm
Carbide is a very bad idea for a spudgun.
The acetlyene (that carbide makes) is much more likely to detonate than are most spudgun fuels. In addition, acetylene at only modest pressures will self-ignite.
Carbide + PVC + ammo in barrel is a good way to hurt yourself.
Carbide is used in noise makers because acetylene has a very wide flammability range in air, 2.5%~80%, so it is easy to get a combustable mixture. In adidtion, carbide is a stable (in the absence of water) solid so it is easy to package, ship and work with.
Carbide is not suitable for a PVC based gun. Heck, it isn't even suitable for a metal gun because of the risk of it setting itself off.
The acetlyene (that carbide makes) is much more likely to detonate than are most spudgun fuels. In addition, acetylene at only modest pressures will self-ignite.
Carbide + PVC + ammo in barrel is a good way to hurt yourself.
Carbide is used in noise makers because acetylene has a very wide flammability range in air, 2.5%~80%, so it is easy to get a combustable mixture. In adidtion, carbide is a stable (in the absence of water) solid so it is easy to package, ship and work with.
Carbide is not suitable for a PVC based gun. Heck, it isn't even suitable for a metal gun because of the risk of it setting itself off.
Posted: Sun Jan 27, 2008 2:51 pm
It would be fine to use in a metal gun Jimmy- just not a Hybrid, i believe 15psi is all it takes to self ignite.
I wouldn't be putting it inside Plastic though, unless it had a wall thickness of around 1/2".
I wouldn't be putting it inside Plastic though, unless it had a wall thickness of around 1/2".
Posted: Sun Jan 27, 2008 4:05 pm
Novacastrian
I disagree. A metal gun may well be able to take the pressure but you still have the problem of the gun firing by itself. Maybe it is just me, but the thought of a gun that fires when it wants to instead of when I want it to sounds unsafe.
When you put the water and carbide in the chamber and close it up it will start to pressurize. If you put in too much carbide there is too great a chance of the gun pressurizing to the point where it auto-ignites. Too much solid carbide wouldn't look like all that much.
I disagree. A metal gun may well be able to take the pressure but you still have the problem of the gun firing by itself. Maybe it is just me, but the thought of a gun that fires when it wants to instead of when I want it to sounds unsafe.
When you put the water and carbide in the chamber and close it up it will start to pressurize. If you put in too much carbide there is too great a chance of the gun pressurizing to the point where it auto-ignites. Too much solid carbide wouldn't look like all that much.
Posted: Sun Jan 27, 2008 4:11 pm
That is a fair enough comment. This could be easily overcome either by using loose fitting ammo or a bleed valve though.
Posted: Sun Jan 27, 2008 9:25 pm
in the book it uses a regulated amount cause it fills a tiny hole and the rest is scraped off. well you pretty much fire it right after you put in the carbide and its mounted to a stand not hand held so it should be pointing at a safe direction before you put in the carbide so it firing by itself souldn't be that big of a problem but i guess if somthing unexpected happens like somebody walks infront of the target then it would be bad cause with any other gun you can not pull the triger but with one like this you would have to point the whole gun up to make it safe. i was just curious if any1 had had one thats all i didn't know that it self ignited.