Potato guns are really cheap fun. I have come up with some really neat designs for some more advanced ones than the one I built. Some of my Ideas included Bolt Action, Semi-Auto, and remotly operated models. However, none of these ideas ever got off of the drawing board.

The Gun that I did Build was Pneumatic, and was supposed to be run by my Boiler (also home built). The Potato guns primary purpose was for paint ball, and I made designs for artillary shells and smoke shells. Unfourtunately, a loss of intrist in paintball by most of my friends, prevented me from compleating this task.

Basically there are two types of Potato guns, Pneumatic and combustion.

Pneumatic-- this is where the projectile is fired by compressed Gasses (air, CO2, Steam,ect...).
For a beginner I dont recomend building this type of potato gun, because this type of gun is much more likely to blow up in your face.

A Pneumatic Cannon Really only needs Three parts, an expansion chamber, a valve, and a barrel. For optimum performance your valve should be the same diameter as the barrel, and expansion chamber (for potatos thats about 3"), the valve should also be one that will allow the gas to quickly pass when you open it. This means that a Gate or Stop valves (like whats on youroutside faucet)wont work, because you won't be able to open it quick enough. The best valves are Butterfly valves and ball valves. However, Ball valves and especially butterfly valves are hard to find in that size and be rated for the amount of pressure it will be put under.

On my Potato gun I had a bought a 1 1/4" Ball Valve (the 3" was $50 and the 2 1/2" was $30) and had a 3" pipe for the barrel and expansion chamber. In between I used reducers to change sizes.

The Expansion Chamber allows you to have a large volume of air behind the valve at the pressure your source is at. (for safty reasons I recomend no more than 100psi) Another consideration is the lenght of the expansion chamber, if it is too long it will take longer to fill, but if it is to short it will not provite enough power. I would suggest a lenght around 1/4 the barrel lenght, maybie a little longer.

Assembling the gun is fairly simple baisically the barrel is glued to a male screw-on connection which is screwed into the valve and the expansion chamber is attached the same. On the end I took an end cap and drilled a hole and screwed in a connector for a hose.

Basically, if you cannot figure it out from all of the information I have given than you have no buisness building one!!!

The Second type of cannon is cumbustion. It is baisically what is sounds like. Personally I like this type better because it is less likely to explode on you (That is if you use it rationally), and it makes a lot more noise.

A combustion potato gun is pretty simple. The barrel, The combustion chamber, and the ignition system. To build one all you need are two pieces of pipe one bigger than the other ( the smaller is for the barrel), a reducer for in between the two two nails screwes or bolts,a screw on end cap, and a replacement pezio ignitor for gas grills.

Take the smaller pipe and saw it down to the lenght you want for the barrel, then take the large piece and saw it down to the lenght for the expansion chamber (preferably no more than 1/3 the lenght of the barrel). now take the piece for the combustion chamber and near whats to be the front drill two holes opposet of each other, and put the nails (or what ever you are using) into the holes so that the tips are about 1/4" apart. Then on the outside attach the Gas Grill Ignitor (one wire to each nail). Now glue on the fitting for the screw-on cap to the back (opposet the nails), this is where you will spray in the fuel (hair spray). finally glue the barrel and the combusion chamber together using the reducer.

If you are planning to build any Potato guns, I strongly recomend you look at other sites (I forgot all of the good ones that I had found) because I have really only given an outline of what it takes to build one.

Some friends of mine built a combustion potato gun that was about ten feet long and had a 4" diameter combustion and a 1 1/4" Barrel, their preferred ammo was lemmons but it shot potatos just fine :-). Their really fun if used saftly. For any one with a resturaunt, Shooting Potatos at a Grate is a great way to make french fries.

All of the information that I have listed is very basic, just to give you an idea of what it takes to build one and the principals behind them. If you are looking to build one then I would suggest Aaron Cake where you can find good information on combustion potato guns, and a large forum. There is also a large database of projectiles and fuels. Back