High Powered Cannon/ Spud Gun !!

About: My name is Brendon and I live on a hobby farm in sunny Australia. My main interests are Gas Turbines (Jet Engines), High Voltage electricity and Computers.

Hi all,

Basically what this is, is a cannon it runs best on petrol,
the cannon can fire a whole range of projectiles from apples
to spuds and metal. 

Here is a video of it firing all sorted projectiles including spuds, an apple, an orange and the metal projectile: http://www.youtube.com/watch?v=cj4Yr0Wbxqg

Here is a video of it firing with out a projectile: http://www.youtube.com/watch?v=URECr3Wb8jY

If your interested in jets here is mine: http://www.youtube.com/watch?v=BHHI9QmIrI8     http://www.youtube.com/watch?v=_t8qsfF32TI

You will need a welder most importantly and the following:


Steel piping for the barrel. (the size depends on the projectile and the canister you are making)

Steel piping or a metal fire extinguisher for the combustion chamber.

Steel plating for the ends of the chamber if you are using pipe.

A spark plug. ( cut the bit of metal off, that the spark jumps across to get a bigger spark for better ignition)

One nut & Two bolts, size of your choice ( one goes in the end of the chamber for the fuel input and to blow the exhaust out, the other goes in the barrel to stop the projectile going into the combustion chamber.

Some aluminium pieces if you are going to make metal projectiles.

Tools basic:

A welder. ( A gas mig works best)

An angle grinder.

A jigsaw for cutting the end plating out. ( you will need a blade for cutting steel)

A drill and drill bits and a metal hole-saw.

Some sort of high voltage source for the spark plug.

Now a word of warning: once you put fuel in the chamber do not point it at any one or look down the barrel and use common sense this can kill if used in the wrong way. I am not liable if you hurt or kill anyone or damage property. Do not use bug sprays for fuel they are very dangerous because they are insecticides which cause cancer or can make you very sick from repeated exposure!
Also be very careful around high voltages, if you are not you may get electrocuted or worse.

The specs of mine are: barrel diameter 5cm, chamber diameter 12.5cm, chamber length 32cm.
To put the fuel in I use a spray bottle like the ones used to wet hair down or water small plants, roughly 2 sprays does me for my chamber ( don't put to much petrol in or it wont be as powerful )2 sprays is about 1-2 ml, I did some tests and the chamber gets up to 100psi with only 1-2 ml of fuel when ignited. 
The aluminium projectile of mine went 150metres.

Does anyone think I should add an instructable about my jet kart which is going to have 90lb's of thrust When its finished?

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Step 1: Step One

Get all your required parts.

Get your steel plating and cut it a few centimetres bigger than the diameter of the pipe to be used for the chamber, with a jigsaw or what your going to use to cut it to a circular shape. Then in one of the end plates cut a hole in the centre for the gases to go through into the barrel, cut the hole a bit smaller than the barrel diameter.

Step 2: Step Two

Weld both the plates to the pipe you are using for the chamber, once that is done drill a hole for the spark plug make sure it is not too big then thread the hole with a hole threader or try your luck at getting the plug in without ruining the thread on it like I did, but make sure you have cut the bit of metal of the tip for a big spark first.

Step 3: Step Three

Next drill another hole next two the spark plug for you to put fuel in and blow the exhaust out. Weld a nut over the hole so you can seal it with a bolt when you have put the fuel in ( see pic ).

Step 4: Step Four

Get your barrel and near the end your going to put on the chamber drill a hole and put a bolt in it to stop the projectile entering the chamber, I welded mine in to stop it flying out from the pressure ( look hard in the one of the pics and you should see mine welded in the bolt that is). After that weld the barrel to the chamber.

Step 5: Step Five

Now your set to try your cannon out you might want to paint it first though, remember to be extra careful with this treat it like a loaded gun!

If you cant get it to fire try getting a bit of fuel on the spark plug by squirting some in the barrel or dribbling some in the bolt hole, if that doesn't work blow the air out with an air gun or something, if it still doesn't work your high voltage supply might need an upgrade for people with barbecue lighters.

Remember to blow the exhaust out each time you fire.

Here is a video of it firing with out a projectile: http://www.youtube.com/watch?v=URECr3Wb8jY

Step 6: Metal Projectiles

If you want metal projectiles you need a hot fire some left over steel from the barrel and a utilux clip that fits the left over bit of barrel.
Cut the left over bit of barrel to about the length you want the projectile to be, on the side of the pipe cut it top to bottom once (the purpose of this is to enable you to get the solid bit of metal out once it has set.

Put the utilux clip on the bit of pipe and screw it up until its tight. Place it on a flat bit of wood so the molten aluminium wont leak out or get dirt on it. get your self a fire hot enough to melt aluminium and melt some aluminium in a tin and pour it into the pipe on the wood. Wait for it to cool then get the lump of metal out and cut it to a kind of pointed shape on the end ( see pic ) also cut the burs and whatnot off so it will fit the barrel.

Step 7: Mini Cannon

Here is a mini cannon that may interest you. shoots anything small enough to fit in the barrel. Its made out of a few scrap bits of steel pipe and plating 

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    13 Discussions


    4 years ago

    I made a spud/apple/pear/slop gun-you get the idea: ) I picked up all of the intended parts at ace. it is made of all galvanized metal piping, for safety reasons. not that thin PVC stuff. its powered by hairspray and/or butane.the striker is from an electronic lighter. in all it cost about $17. that's pretty good considering it can shoot up to 100 feet.


    7 years ago on Introduction

    Yea that sounds like a good idea standing a little bit back with oxy acetylene i wanna run with a oxy mapp gas set up since i cant get acetylene so it should still be good with mapp. Also what type of ignition are you using with the spark plug.im going to use a lantern sparker but the way i designed it i should easily be able to interchange the ignitions which you should be able to do too.

    1 reply

    Reply 7 years ago on Introduction

    I was using an ignition coil driven by a capacitor and light dimmer, not very portable but good for shredding stuff though. I might use a relay and maybe an ignition coil for a portable one ( for distance firing hook it up to an Remote control car circuit). Please be careful with the oxy mapp mixture, I nearly lost my hearing and hand from a careless mistake with the oxy acet... in a milk bottle ( it was awesome though). Have fun!


    7 years ago on Introduction

    Hey this is kinda late but im building a steel spud gun its going to have a 3" chamber and a 1.5" barrel how thick is the plate of the end of the chamber i have a flux cored welder so i cant do anything too thin i was thinking of 1/16-1/8 thick the pipe is about that thick. Also have you tried oxy-acetylene in your gun yet.

    1 reply

    Reply 7 years ago on Introduction

    Hi, thicker is always better unless your in for weight saving, I think what I used was around 1/8 or something like that. But I made a smaller version about the same size as what your going to make... didn't work too well, getting the fuel air ratio correct was finicky. When I got it right it only shot a large marble 17 metres or 55 feet :( . I haven't tried oxy-acetylene yet, need to sort out a remote firing setup in case it blows apart. Any more questions just ask.


    8 years ago on Introduction

    this is awesome, but i question it's safety. did you pressure test the welds and steel? how far does it shoot?

    also, a plastic potato cannon is one thing, this is something else entirely. this could get you put in jail just for having it, depending on what state or country you live in.

    other than that, this is AMAZING. would love to see a video of it blasting various things.

    3 replies

    Reply 8 years ago on Introduction

    I am not concerned about the actual thing blowing up because the pipe is thick
    (the pipe is the liner from an old bore) it should hold 100psi with ease. My projectile travels 150 metres or 492 feet.

    Any ways I think a thick steel cylinder is safer than a thin piece of pvc pipe.
    Hope I don't go to jail ! Will get some videos later hopefully :)


    Reply 8 years ago on Introduction

    I will do, the engine is pretty much made I still got to get the steel for the kart that it is going on, and the oil pump.