Posted: 7/18/2009 2:31:31 PM EDT
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Here's the skinny:
2'x4" combustion chamber 5'x2" barrel Aqua Net works fine as a fuel...potato = about 100 yards, and that wasn't even a perfect seal. Recommendations on fuel? Also, I'm assuming the better the seal between the potato and barrel will result in a longer shot, right? Any other tips? |
Regarding the seal you spoke of. I had one of these years ago. To make the seal very tight I turned a 45 degree on the muzzle. Then when I pushed the potato down the barrel the sharp chamfer would cut the potato to the perfest bore size. Result? Out of a 4 foot barrel I could send a potato about 250-300 yards. The bore was about 1-1.25 if I remember. Been awhile.
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Your chamber seems awfully long. How many ignition sources are you using? I use starting fluid (ether with some other additives) in mine. If you use too much it won't light. You only need to use a really short blast, but it burns clean and won't get everything gummed up like hairspray. |
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I used acetylene. (put calcium carbide rocks in water)
gives LOTS of power. I ignore the idiots that claim you will kill yourself, they don't have a clue, fired it tons of times and the worst I've seen was a crack in the end cap (which I just replaced). Just be sure to check for obvious signs of stress and you should be good. I didn't add extra oxygen though (if doing it through an oxy-acetylene tank it would be that much more dangerous)..... |
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Use the solenoid valve from a lawn sprinkler, and charge the reservoir with compressed air. MUCH safer than combustion. I made one this way and it would get 250 yard shots easy. It would also launch about a half gallon of water a good 50 feet. When launching water, the thing actually had considerable recoil.  |
Alcohol dulls the pain, somewhat... That is all.
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These are inherently unsafe and I would not advise you look at the following link for technical information nor construct and fire one.
Spudgun Technology Center "Wouldn't be prudent" |
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Quoted:
I used acetylene. (put calcium carbide rocks in water) gives LOTS of power. I ignore the idiots that claim you will kill yourself, they don't have a clue, fired it tons of times and the worst I've seen was a crack in the end cap (which I just replaced). Just be sure to check for obvious signs of stress and you should be good. I didn't add extra oxygen though (if doing it through an oxy-acetylene tank it would be that much more dangerous)..... Yea do not add o2!!! I found out the hard way.  The only suggestion I have is that use a smaller barrel. I found that a 1.5" is the best size for accuracy and distance. Also you can use smaller ammo.
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Quoted:
I used acetylene. (put calcium carbide rocks in water) gives LOTS of power. I ignore the idiots that claim you will kill yourself, they don't have a clue, fired it tons of times and the worst I've seen was a crack in the end cap (which I just replaced). Just be sure to check for obvious signs of stress and you should be good. I didn't add extra oxygen though (if doing it through an oxy-acetylene tank it would be that much more dangerous)..... As long as you keep it under 16PSI your good. Old school shops used acetylene generators utilizing carbide and water(lot of people died using them) I don't recomend, but have heard that if you snuff out a torch running a neutral flame and fill the gun's chamber with that mixture, it is the perfect spud gun fuel. I have filled upside down coffee cups with this mixture and blown them the-fuck-up! It takes very little gas! |
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rubbing alcohol. learn it, love it. I haven't messed with one of those since I was a teenager. My grandfather who was a Master Chief Gunners Mate on the IOWA loved that thing. I don't think I ever saw him giggle like a little boy more than when I shot that thing in front of him.
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Quoted:
Potatoes are expensive. Green walnuts are the way to go. Put a sharp taper on the outside of the barrel to trim the walnut hull to size. If you got to the grocery, they throw away vegies and fruit on an almost weekly, if not daily basis. Talk to a supervisor in produce or the store manager, they may be able to hook you up on the cheap. When I was in HS, I worked in a grocery store and would get apples by the box for 50 cents
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Quoted:
Potatoes are expensive. Green walnuts are the way to go. Put a sharp taper on the outside of the barrel to trim the walnut hull to size. Did you used to be my neighbor?  We ran out of potatoes and started using green walnuts from my tree and they are the best! Then we ran out of hair spray and started using spray paint too. Had to clean the igniter tips more but it worked too. We were launching those green walnuts 300 - 400 yards (more like 200+, I just looked) easy with a 4' fireball out of the muzzle!
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| Starting fluid and your chamber is fine. The barrel may be a bit too long? After putting a nice chamfer on the outside of the barrel for trimming the potato, apple, whatever I put a small chamfer on the inside of the barrel also, makes for a tighter fit and a good loud crack when launched. I have launched hundreds of pounds of potatos and its a blast. |
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Quoted: Use the solenoid valve from a lawn sprinkler, and charge the reservoir with compressed air. MUCH safer than combustion. I made one this way and it would get 250 yard shots easy. It would also launch about a half gallon of water a good 50 feet. When launching water, the thing actually had considerable recoil. yeah I made one like this and it was bad assed had an angel paintball grip and even added a safety switch to it. I could shoot oranges(had a tree in the backyard) 200 yards @100psi easily. sold it to my friend who still played paintball I built it as a rocket launcher and those little Nerf footballs with the tails would go 300 yards slightly sub minute of mountain. |
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Propane is a more effective and easy to use fuel then any hairspray. You can do it real cheaply using a blowtorch and tank. Just open the valve of the torch attachment stuck inside the chamber for a few seconds. Close the valve, cap the chamber and enjoy the boom. Experiment to get the right amount of fuel. You can also assemble a metering pipe that will measure out exactly the right amount of gas every time.
If you do continue to use hairspray I recommend mounting your ignition system on the end cap. It will get less gummed up that way. |
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my friend (also a member here) made a Hybrid potato cannon using propane and oxygen injection into a high pressure sealed environment This thing was outfitted with a golfball barrel from STC and it would be an understatement to say it could outdrive tiger woods. It could also put a golfball through a 1x6 wood plank like a knife through butter. Also it was outfitted to be fired remotely since we were sure it would explode and kill us all, it never did though.
If i had somewhere to shoot one now, i would build a big fucker with pressurized gas and a stun gun ignition system... and fire it remotely from a safe distance. |
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Quoted:
Starting fluid and your chamber is fine. The barrel may be a bit too long? After putting a nice chamfer on the outside of the barrel for trimming the potato, apple, whatever I put a small chamfer on the inside of the barrel also, makes for a tighter fit and a good loud crack when launched. I have launched hundreds of pounds of potatos and its a blast. Won't the starting fluid attack the adhesive being used and weaken the PVC itself over time? |
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I'm guessing we were shooting spuds at least 200 yards! Lots of backyard tomfoolery fun. FYI...the entire cannon is reinforced with a duct tape wrap to prevent any kabooms...my 12 year old son suggested we write "Glock" on the side! Aquanet seems better than Right Guard.
There are actually websites dedicated to spud guns. Holy Mother of Dork...I don't know what's worse - the fact that there are such websites - or the fact that I actually checked them out.  That's where they suggested the 1:2.5 ratio between combustion chamber and barrel length. Any way, nobody is hurt or burned...yet. My inner adolescent is amused. Mrs. Blake...not so much. 
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Quoted: Quoted: Use the solenoid valve from a lawn sprinkler, and charge the reservoir with compressed air. MUCH safer than combustion. I made one this way and it would get 250 yard shots easy. It would also launch about a half gallon of water a good 50 feet. When launching water, the thing actually had considerable recoil. yeah I made one like this and it was bad assed had an angel paintball grip and even added a safety switch to it. I could shoot oranges(had a tree in the backyard) 200 yards @100psi easily. sold it to my friend who still played paintball I built it as a rocket launcher and those little Nerf footballs with the tails would go 300 yards slightly sub minute of mountain. Many people are familiar with Tony Chachere's Creole seasoning. The company also produced a small tin of file' powder for gumbo. It just so happens that those cans of file' powder fit perfectly inside a 1 1/2" PVC pipe. I decided to experiment. Suffice it to say that 120 psi. in my rig was powerful enough to shatter a cinder block at a range of about 10 feet, and fill my garage with a green spicy haze for about ten minutes. |
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Quoted:
Quoted:
Starting fluid and your chamber is fine. The barrel may be a bit too long? After putting a nice chamfer on the outside of the barrel for trimming the potato, apple, whatever I put a small chamfer on the inside of the barrel also, makes for a tighter fit and a good loud crack when launched. I have launched hundreds of pounds of potatos and its a blast. Won't the starting fluid attack the adhesive being used and weaken the PVC itself over time? Hasn't in years of use. You only use a very short burst, less is more!! |