The Original Potato Cannon

Step 2 Assembly

-Cut the 3" pipe to about 13" or a size you prefer (the larger the combustion chamber; the more gas; the more boom)
-Make sure the reducer fits over the pipe
-Spread some ABS cement on the inside of the reducer and outside of one end of the pipe, slide the reducer onto the pipe with a twisting method
-Repeat this for the threaded adapter
-Repeat this for the barrel (5' of 1.5" pipe)

Make sure your gluing is done properly, you dont want it to explode.

Comments

[_Con]

Just make the combustion chamber galvanized pipe, then use a threaded bell reducer down to sch.80 pvc for the barrel . Will work perfect, not as heavy as a full galvanized pipe gun, but as strong as one.

[Tux0r]

PVC explodes like a hand grenade, Go with ABS instead. Trust me, I had a friend that make an all PVC model and it turned into a bomb instead of a cannon. he lost an eye and an arm.

[rangoonboth]

What did he use, Gun powder. Hair spray or alcohol based sprays wouldn't do that. I think you're exaggerating.

[ilpug]

pvc is much better, you just need to use the right amount of propellant.

[Tux0r]

Like zippy said...abs ruptures and releases the pressure and pvc splinters into many thousands of pieces and moves at at least 900 feet per second. By the way, PVC is better for water lines, not for potato cannons unless you want a pipe bomb.

[zippydaspinhead]

Pvc also splinters into thousands of peices under too much stress. Peices that are sharp and moving FAST.

ABS just ruptures. Much less chance of injury

[Turnip123]

Especially since this instructable has become so popular, I though I might let you know the potential safety problems with ABS.

Unlike PVC, ABS is not rated for any type of pressure, and is actually a more dense version of Styrofoam.

I built a potato cannon like this about 2 years ago, and it was going great until the threaded adapter, shot off, engulfing my friends hand in flame and giving him severe 3rd degree burns.

I love potato cannons, and really wouldn't want to flag this, could you just change the materials to PVC? Those are actually meant for pressure loads.

[davison112]

My dad was a marine, and he told me that mortars where made of abs... ;O

[matt]

PVC is not good for combustion cannons. It will break.
ABS is fine for combustion.

PVC is good for pneumatic cannons. Make sure you use schedule 40 PVC this is good up to 220psi.
ABS is not strong enough to use for a pneumatic cannon. It will shatter.

[Turnip123]

Pneumatic and combustion both are rated by PSI, a rapidly expanding (combusting) gas, is liable to shatter ABS (due to a less uniform design/brittle material).

Therefore, should the potato get wedged good enough, you could have a similar/worse experience than that of my friends.

[struckbyanarrow]

the reason we use abs is that it tends to rip rather than shatter in little fragments like pvc

[dolmandabean]

ah yes.. i remember the final experiment from my last potato cannon.. the potato was about 15 cm long.... just blew itself apart... the spud went but the end cap nearly took my friends leg off!

[Nattwood]

why not solve everything and make it out of galvanised steel with decent weldings, that oughta do it.

[Turnip123]

Well, PVC is much cheaper/lighter/easier to fabricate/etc.,

And while not as good as galvanized steel, is a much better use than that of ABS.

Which is meant for water drainage, and is literally, made of Styrofoam.

Dont believe me?

Take a sledgehammer to PVC and a tack hammer to ABS, and I guarantee you, you will have but mere ABS slivers with a minimal force applied.

[Nattwood]

hey

well i dont disagree with the abs verses pvc, but nor do i really care about the cost and fabrication when it comes to optimum performance, and so if make something a little heavier means that optimum range of compression goes from 80 psi to 400 there is nothing to stop it from happening in my eyes, i might even post it, just gotta fgure out welding plans, cause i got access to any knd but i dunno which would be best suited.

[Turnip123]

Well, if you really want to do that, I would be glad to advise, I have experience with welding and metal fabrication. As well as Pyrochemistry, and easy to manufacture propellants and lift charges.

The legal concerns might be something to worry about, you're getting into field artillery now, haha.

The only thing to worry about would be the strength of your welds, Argon and CO2 is going to be must, if you have access to TIG, that would be perfect.

[Nattwood]

well im not really sure as to legal implementations on any of this stuff and unless u live in brisbane, australia then i higly doubt that u would too, but i do believe at this rating that yes it would be considered a weapon very much so. i dont have a tig at home but i have one at school but there would be questions as to why i was welding pipes in the certain shape. i do have mig, arc and oxy at home though. ive also been thinking about combustion methods because using the everyday feuls i was hoping wouldn't make it any more powerful than pvc, only heavier. but using high flash point fuels like petroleum and adding compressed air in at 5 atmos (70psi) would alow for a much greater KABOOM. protection is therefore a must.

[codz30]

If you're planning on making a spudgun completely out of metal, I highly reccomend making a hybrid or pneumatic as a plain old combustion won't do your hard work justice.
A full metal spudgun with a decent piston valve could handle pressures of about 400+psi, which is about 8 times more than what you would get from a combustion.
Hybrid spudguns have been known to break the sound barrier.

Anyways, I hope you change your mind!

[Nattwood]

yea, im not changing my mind, and yes i do understand that when it comes to the metals plain combustion would be useless so thats why ive thought of a way to make it hybrid. adding fuel to the chamber alone wouldnt increase it so i thought about adding 5 times as much fuel and increasing the compreesion in the chamber by adding 5 times as much air as it would hold or just adding as much air for maximum flash point, because at this higher pressure there is going to be a rapid increase from about 100psi to well above 400psi and it doesnt have to be stored energy either, think about the equations for a second, if i have air in the chamber at standard air pressure(14psi) and 10 ml of degreaser and that makes the output of the combustion launch the projectile at about 100fps muzzle velocity how much would 50ml of degreaser and 5 times the air pressure(70psi) make the speed be increased by, this is lethal technolody where getting into here if it were produced properly, eventually this could be an outcome in gauss, launching 1kg objects from a cannon at unstoppable rates of speed for such little fuel, and much less science.

[grim551221]

the abs sement dried quickly, and getting the gas to axyigen ratio isn't hard, bud if you get it perfict, it shoots far!!!!!!!!!!!!!!!!!!!!!!!!!!!!1 SAWS ARE AWSOME 0)

[Nexnaught]

What is the gas/oxygen ratio?(how long u spray?)

[hackmattr]

The propellant can not ignite if its not the right air/fuel ratio. If you spray too much propellant into the combustion chamber, you need to wait for some of it to dissipate so thats theres more oxygen. If you spray too little, then the cannon won't go off either.

[mr.break_it]

12,000 volt ignitor work?

[119662]

will the pvc melt under the explosion?

[Drifter921]

no, the heat desapates too fast, it's like moving your hand over a candle quickly, your hand isn't on the candle long enough or is at the right angle to feel any burning on your hand, same thing applies with this

[mavogt]

also make dang sure you glue dryes fo at least 12 hours or the fumes in the glue can ignite and that is really bad. I also prefer PVC

[DR..]

im scured of saws!!!!:(

[babybackribs]

you cant put too much gas in, you need the right ratio of gas to oxygen for it to ignite