OT: potato cannons

[67cst]

hey guys i got a question, im in the middle of building another potato cannon...my question is i wanna use a spark plug on this one, how can i get a spark to it?? easyest the best...also lighter the better, would a 9v battery work? thanks in advance guys

Derek

[ozarkhippie]

hehe I still have one, I haven't heard of using a spark plug though.

[oldyeller]

well, you could use a flame thrower set up, 12v battery and a coil, 9v might work, but you will still need a coil, there about 9 bucks new at the local parts store for a cheap one..

[67cst]

old yeller? pls explain

[67cst]

also i have a psi gauge for the combustion chamber, when the explosion occurs will this destroy the gauge?

[Steven Sellers]

Hehe the gauge unless it is rated for much higher than the force the explosion will cause, will be destroyed.

[67cst]

if i had a valve in between the chamber and gauge would that work, like when the propane is going in the chamber have the valve open and once i reach operating psi i close the valve before firing?

[Steven Sellers]

Yes but the problem would be is making sure you get a decent one so it holds. The gauge definetly would not take the shock

[67cst]

okay, also i wanna have a propane tank mounted beside the chamber, and a hose off the propane directly hooked to the chamber, with a valve...but im having problems finding something that will thread onto the propane that will also push that pin in to realease the gas...what would work in that case

[GMC71k20]

i made a potato gun for a school project but they wouldnt let me bring in my combustion propelled one so i made one out of PVC piping that would run off compressed air, stomp the valve really quick and it did much better than my other one.

[67cst]

gmc71k20-im making one at trade school, in the welding shop, my teacher likes the idea but its sorta on the downlow, i pretty much have it all welded up but now i gotta do the thinking....

[still w.i.p '68]

Unless you are just wanting the sprak plug, I find it easiest to use an ignitor off of a BBQ grill , its self contaned, requires no batterys, and is quick like a trigger....Good luck, and let us know, Oh by the way , have you ever built a tennis ball cannon, the ball is used over, and over..

[67cst]

nope never have...how do they work...?

[oldyeller]

are you using a 20 lb propane tank, like for a BBQ? why not go to walmart and get a new hose and connector for a BBQ that would connect to the tank, this would solve your fuel supply problem..

As for the spark plug, get one that is long( has alot of threads) that way it will stick into the pipe close to the center. use a coil plug wire to go from the coil to the spark plug, then wire the coil coil to the battery with a monotary switch ( the type that makes contact when you push it and is open when you let off) in the positive lead. This way you will gas up the chamber, close your fuel valve( make sure it is a good one so it doesn't flame up your hose and blow your tank and you up) and hit the button, when you hit the button it will send about 30,000 volts to the plug, so watch where you hang on to it, it will hurt...

they just did a flame thrower install on the show trucks this last weekend... watch for a rerun

[67cst]

i have a green coleman propane tank (16oz) the big bbq propane tanks have different fittings...hmmmm

Derek

[Hooter]

I usually just use a Bbq sparker and some hairspray . Don't you just love the sound of a spud gun?!

[chevykid04]

me and my friend are in the process of making one....grill igniters, work great.also sometimes, if you wrap a peice of paper around the bottom of the potatoe, it makes a better seal and more friction = more distance my friend who use to work at my work , would shoot them out the exhaust hole in the door, over the freeway

[Mitzki5]

I see a couple problems with your idea. First, not only will you need a propane bottle but you would also need a way to put air in with the propane. Then you have to figure out the correct ratio of air to propane. Don't bother with the gauge. You will not be able to pressurize the combustion chamber. Once you stuff your potato in and try to pressurize, the pressure will push the potato out. You only need to pressurize the chamber if you are making a pneumatic launcher rather than a combustion launcher. I agree with the other people. A grill ignitor works the best. Another tip that I have read and applied to my laucher is to make sure the size of the combustion chamber is double the barrel (potato shoot) is. I used a 4" diameter pipe for my combustion chamber with a 2" pipe for the barrel. Here's a website I found a long time ago. I haven't checked it out lately.

http://www.spudtech.com/

By the way, potato guns are fun but they can be VERY dangerous. So be very carefull. The above post are just ideas and I am not held responsible for anything that you do with the info above. I know this is stupid to put this last paragraph on here, but it makes me feel better.

[whitdog72]

man u guys are getting way to technical....the best thing i have seen with the most spark is a Lantern Lighter...i have seen them at Right aid, and Big 5 sporting goods i am sure any sporting good carries them, the thing is in the shape of and L ......the long end of the L is a twist nob which twist the other end where the 2 ends meet in the L has a flint or so on it it almost Work the same as a Torch Stricker......it will prolly be easier for me to draw a quick pic in paint then it will be to describe it......i have always used hair spray on my guns soo after a while the flint will get wet so u will have to let it dry a lil bit but we had one rigged to where wall nuts with the green shell on them would fit right in the barrel got them to launch a hundred yards or so good times! lemme know if ya wanna know more i'll try a quick pic of how mines set up

[whitdog72]

i have bought one before around 3 bucks or so like i said works the same and a torch striker or a cig lighter

[whitdog72]

kinda what it would look like in the gun......put it in the middle for best spark i guess

[694X4]

I am building a pnematic one right now with a electric lawn sprinkler valve. This thing should be awsome the valve releases in like 1/10 th of a second. I also have one that burns hair spray and uses the lantern lighter and it works well. There is lots of stuff on the net about these.

[Yukon Jack]

How about some pumpkin chunkin - 67-72 style!

[694X4]

Hell yes that is awsome now it just needs to be 4x4 so we can take it to Iraq and run in the sand. Old Sadam wouldn't know what hit him if he got nailed in noggen with a 10 pound punkin.

[Bamm]

Here is how the one I used to have was set up. Just like Whitdog72's but instead of having the spark in the side I put an end cap on the big end of the pvc pipe and drilled a small hole in the center of it. I used a candle lighter that was only a buck or two at walmart. The ones that have the trigger and are about eight inches long. Most people have 1 or 2 around that are out of fluid anyway, and thats all the more better. Load potatoe, take the cap & long straw tube off a can of brake cleaner, wd40 whatever and put it on your hairspray can. insert tube in the hole, spray, insert candle lighter and pull trigger. WWhhooooomm. I have been thinking about using smaller pvc pipe, say 1" or 1 1/2" and instead of potatoes or tennis balls, trying snow. It's cheap and plentiful in some places. If I could have had one of these when I was a kid, those snow fort snowball fights would have been much more fun. Later............Jerry