What is the safest material to use as a combustion chamber

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Rob748
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Hi I was wondering what the safest and strongest material to use as a combustion chamber is.

I was thinking of going 3 in schedule 40 steel pipng that is about 20 inches long and a 65 inch barrel. Its going to be a advanced combustion. Id like to be able to shoot marbles out of it using a very small barrel.

Could I use 3 inch Schedule 40 steel with a 3/4 outside diameter barrel >?? or whatever fits best for a marble. Or could I use 1 inch and shoot someother kind of projecile at very high speeds hopefully over 500 fps ?.
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Radiation
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Sun Feb 22, 2009 9:15 pm

That's unnecessary sch 40 pressure rated PVC is more than adequate for any standard combustion. Check my sig as it matches the general description of what you want to do with your gun.
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Rob748
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Sun Feb 22, 2009 9:17 pm

Lol I dont know what u mean by sig... but I want to go metered propane and a burst disk. If I used Pvc I want schedule 80 lol
Rob748
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Sun Feb 22, 2009 9:21 pm

Or I might just go 2 in steel chamber.. just to shoot small things really fast lol
jmeyer1022
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Sun Feb 22, 2009 9:22 pm

Rob748 wrote:Lol I dont know what u mean by sig... but I want to go metered propane and a burst disk. If I used Pvc I want schedule 80 lol
Completely unnecessary, The spike pressure of any combustion MAPP or propane doesn't reach nearly the breaking point of SCH 40 pipe.

I believe a well built combustion only reaches 60-70 PSI tops and its a spike rather than like in a pneumatic where its holding the pressure. If you want to spend the extra money on SCH 80 go for it.

Also I suggest going with Cam locks for a burst disk and for metered propane check out

http://www.burntlatke.com/lp.html

For getting the propane fitting threaded I suggest going about it this way

[youtube][/youtube]

Good luck and keep researching =)
Rob748
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Sun Feb 22, 2009 9:25 pm

Thanks... Ill prolly go schedule 80 just to be safe lol.

I want to have a fan, metered propane, and a burst disk that doesnt give away until like 50 psi or so.

How fast do you think it would shoot a marble with a 3 in chamber that is 15 inches long. and has a 60 inch 3/4 barrel ? or should I go 2 inch chamber at like 25 inches long to compensate a little bit ?

What setup would propell a marble at the fastest speeds

thanks :D
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Sun Feb 22, 2009 9:31 pm

spoiler alert: my gun currently uses a burst disc and Mapp it's absurdly powerful. Quite honestly this isn't a weekend project type thing to get this kind of performance while safety is important you are not being logical here. schedule 80 is hard to find and entirely unnecessary, steel is small and difficult to get to work in advanced setups not to mention heavy as hell. Stick with pressure rated PVC and work on making it advanced rather than worry about using unnecessary materials.
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Rob748
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Sun Feb 22, 2009 9:34 pm

Ok OK OK Ill use schedule 40. How fast do you think this cannon could shoot a marble lol
jmeyer1022
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Sun Feb 22, 2009 9:38 pm

With a marble I'm guessing you'd easily get 750+ FPS.
Rob748
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Sun Feb 22, 2009 9:42 pm

Thanks Jmeyer :D Which setup would you prefer to get the highest fps possible ?



750+ fps !!! thats faster than most bb guns lol... This cannon will be awesome !
Rob748
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Which setup would work the best ?


3 inch Chamber, 20 inches Long. Metered Mapp gas, a fan, Burst disk at 40-50 psi and a 3/4 outside diameter (or whatever barrel size is required for a marble) thats 60-70 inches long, and a gas grill sparker ?

Or 2 inch with the same setup ?

what Im afraird of is having a barrel to small, and when the fuel ignites it exerting alot of pressure on the chamber because of the small barrell size. Would I be fine with such a small barrell size ?
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Sun Feb 22, 2009 10:01 pm

I don't know how fast it will shoot a marble. I hate marbles. Terrible ammo, inaccurate, poor penetration due to light weight and when they explode you basically get a cloud of glass dust. Not so fun to breathe in. Personally I have quit using marbles all together.

As far as your chamber question I have tried small chamber of about 2 by 6 inch. It works well, but my 3x14 works much better. Plus a small chamber is a pain to make advanced. Heck the 3x14 is a nightmare to construct.
Last edited by Radiation on Sun Feb 22, 2009 10:09 pm, edited 1 time in total.
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Rob748
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Whats another Kind of ammunition I could use that would fly straight and hit hard ?
Rob748
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The CANNON !!!! lol
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Radiation
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did you check my signature? It has many answers for you.
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