My first metered propane cannon :)

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.
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Thu Mar 06, 2008 10:24 pm

24in of 3"sch40 coupled to 26" of 1.5" sch40

made my own regulator from an inline pneu-trol valve which i rigged to have a psi gage hooked onto it.

enjoi! ;)

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elitesniper
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Thu Mar 06, 2008 10:31 pm

you should get a longer barrel and shorten the chamber, but thats pretty nice
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Thu Mar 06, 2008 10:58 pm

elitesniper wrote:you should get a longer barrel and shorten the chamber, but thats pretty nice
yeah i was thinking that as well. But i wanted to go with something portable but with a larger than normal combustion chamber to try and pack a bigger punch. Now i just need to dial in my propane.

Please if anyone sees any flaws in this thing lemme know because i am relatively a newb to this.
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elitesniper
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Thu Mar 06, 2008 11:02 pm

if you shorten the chamber it will pack a better punch because the flames will take a shorter time to push the projectile out in a short chamber, as in a larger chamber they will need to travel for a little before reaching the projectile.
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jook13
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Thu Mar 06, 2008 11:03 pm

I am not seeing a chamber fan. If you add one it will become a lot more reliable/ better. If I were you I would add the fan, then put a 2 inch ball valve on the butt end of the gun so it would be easy to open and vent after each shot. Other than that it looks like it does pack quite a punch. nice work.
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Thu Mar 06, 2008 11:18 pm

jook13 wrote:I am not seeing a chamber fan. If you add one it will become a lot more reliable/ better. If I were you I would add the fan, then put a 2 inch ball valve on the butt end of the gun so it would be easy to open and vent after each shot. Other than that it looks like it does pack quite a punch. nice work.

good call,

i have not done all my research yet on the chamber fans but i will most likely make that an addition to this gun.

thanks for the ideas!
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hi
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Thu Mar 06, 2008 11:41 pm

its a good cannon. i have one of similar size. i have the appropriate sized barrel, but i also have a 3 foot barrel, just because its easier to use, but the main reason is that its much louder, which makes it much funner. :lol:

my only suggestion for your next one (i can garentee you you will build another one) is that instead of using that "y" shaped tee for a handle, get a 1'' tee, cut the bottom half off so it is flat, then use 1'' pipe and an elbow to make a handle. you can simply use a hose clamp to fasten it to the chamber. its much more comfortable than what you have.
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starman
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Thu Mar 06, 2008 11:59 pm

I agree with other comments and add that you consider a stun gun circuit instead of your BBQ ignitor. The fan is also a must-do as well as the intake vent.

That's one big A chamber you have there, relative to the gun as a whole. A chamber half that size with your short barrel would still be loouuud. Could optimize a bit...add 12 - 15" to your barrel length, take away say 6" from the chamber. Would still be handy and loud and somewhat more efficient, although still no where close to ideal. Ideal c:b (chamber:barrel volumes) ratio for a propane combustion is .8:1.
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Davidvaini
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Fri Mar 07, 2008 12:27 am

I say add a chamber fan and you really gotta paint it... if you don't paint it then its just another combustion.


As for the sizes... Id say go for 11" to your barrel and shorten your barrel about 5 or so inches and you'd be golden.
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Spitfire
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Fri Mar 07, 2008 11:20 am

Where did you get the Adapter for the propane tank. I got myself a tank like that today, and the place that had the tank did not have the adapter, unless i butcherd the torch that one normaly buys with it.

Other than my little question, nice gun.
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Jared Haehnel
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Fri Mar 07, 2008 11:28 am

As for the sizes... Id say go for 11" to your barrel and shorten your barrel about 5 or so inches and you'd be golden.
:shock: Huh?

Nice shop set up. If only I had a shop like that....
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C02 tank hybrid
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th3p0p0
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Fri Mar 07, 2008 12:30 pm

very nice all it needs is a fan it makes it fire every time and gives it a huge power increase. and if i was you id chop off the barrel with 1 1/4" of the pipe left and glue a 1 1/2" female so you can have more than one barrel.
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Fri Mar 07, 2008 1:34 pm

Spitfire wrote:Where did you get the Adapter for the propane tank. I got myself a tank like that today, and the place that had the tank did not have the adapter, unless i butcherd the torch that one normaly buys with it.

Other than my little question, nice gun.
the tank is connected to to one of the regular old nozzles that you can buy anywhere like lowes.(the ones you need to use a striker to start the flame) I then put it in my vice and dremel'd the nozzle to take the bend out of it.Then i went to Penn-Air(local place in PA) an got a 7/16" compression to 1/4" male pipe fitting. I only asked for one when i went in there and the guy just gave it to me...haha. And then the 1/4" part of the compresion fitting goes into my regulator.

thanks for the props guys. I will try and get a video up.

here is s vid of my first(other) gun. :D
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