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What pipe to use for a potato Cannon

Portable Welder

Cast Iron
Joined
Jan 9, 2015
Location
Milan, MI
I have some 2" ID DOM tube that has a 1/2" wall thickness, I was thinking that should be sufficient to make a potato launcher with a little Pyrodex powder used for muzzle loaders.
 
Theres a reason I'm here asking questions first, any insight would be appreciated.

Tons of people make potato launchers with schedule 40 plastic and a aerosol can for the propellant.

I'd like to build something safer.
 
I swear, I will never understand why every time simple cannons or launchers are brought up on this site, why everyone turns into a fucking insurance analyst.

I cringe to think of a childhood that didn't include potato gun projects.

OP: I mainly used PVC, but we did make some golf ball and tennis ball launchers from steel pipe/tube.

I think DOM tube is a fantastic start if you want to just assembly things "OOTB" and not have to spend significant time boring or turning.

Is the tube steel or aluminum? Either way it's going to be pretty stout. If it's steel, it's gonna be pretty heavy... we always made the potato guns such that you could at least hold them and 'hip fire' them. We'd put a piezo igniter threaded into an end cap of the chamber, typically. We typically used gas as the ignition source though (started with hair spray and then worked our way up to more 'exciting' chemical aerosols) so if you're going to use powder, obviously you need to make an appropriate flash.

If you're not already experienced with muzzleloaders, I'd get powder advice from someone who is. It shouldn't be too hard to come up with a safe load that'll launch a tater a pretty good distance. Just don't get too crazy.

The best thing about the DOM tube is that it's very smooth inside, like PVC pipe is, which works wonderfully. Friction will directly rob you of all the force of your ignition - which will also increase pressure behind the spud. Reducing friction reduces pressure which increases safety.
 
Black powder and its substitutes behave very differently when there is an air space between the projectile and the powder charge or if the projectile is seated firmly against the powder charge. It is not unusual to bulge a barrel if the bullet is not seated firmly against the powder charge. Be very careful!

Bob
WB8NQW
 
Here is my advice, grudgingly, due to safety concerns if someone reading this misunderstands.

I would not suggest under any circumstances using black powder or Pyrodex in that tubing. If you absolutely feel you have to try please machine a separate chamber out of solid stock with a mortar style powder chamber of less than 3/4" diameter and limited depth so it can not be overloaded. I think no more than 60 grains of coarser (FFg or equivalent) powder should ever be used or you risk your life. I know someone whose son built a spud gun with a fairly large chamber he filled with oxy acetylene. It put a raw potato through a sheet of 3/4" plywood. When he found out he dismantled the rig with strict orders against reconstructing it.

Do not misunderstand - I AM SUGGESTING THAT YOU DO NOT BUILD A SPUD GUN USING POWDERED PROPELLANT! IMO it is not only extremely dangerous but may even violate your local laws.

The only reason I suggested a chambered design at all is to help prevent an even greater hazard if you ignore the warning above.

Edit:
JNieman,

I think the reason for concern for many of us is that if long distance advice is misunderstood someone reading this may get hurt. While the OP seems to have sense someone else reading this might make a mistake with tragic results.
 
Steel mortars are very common, in larger sizes, in the fireworks world. Everything there is black powder. They get buried.

But why do you want to turn a potato cannon into an actual firearm? That loses rather most of the charm, I would think.

I've made my share out of PVC. I've had one shatter on me. ABS is better and polyethylene would be the best. Steel sounds... Unwieldy. Not to mention steel full of black powder (with a fuse?) Says pipe bomb to every cop anywhere.
 
Thanks for every ones input. J Nieman, Over at the Miller site, we have some that say never weld on gas tanks, In my line of work I'm always welding on fuel tanks, Like every thing there is a proper procedure on how to do it safely.

Thats why I'm here asking questions.

I do understand that you can give step by step instructions to some and they wrongly misinterpret something and kill themselves.
 
Gray Beard has a cannon site at; http://www.go2gbo.com/forums/blackp...tillery/?PHPSESSID=nsphtcm2qrhv2mbjlcj6t2hfm6 On that site they have extensive technical advise and specifications for building safely. They are very safety conscious, conservative and willing to help.
For powder propellants I think that the basic recommendation is that the chamber ID should be no larger than 1/3 of the OD of the devise. Ive never built a powder propellant devise but with gas,,,, 2" #80 pvc with ether in cold weather and butane in hot worked well..... I was told. wink wink
 
lawn sprinkler valve work real well for pneumatic tennis ball launcher. And it lite being made completely of PVC. suppose you could swap to potato if you got a thing for spuds. :D
 
why not just use compressed air?

Those pneumatic drain blasters make a great basis for tennis ball guns. All you need to add is PVC pipe with a cap with threads to go on the spigot at the end of the blaster. And they can be quickly reconverted back to clear drains although anyone who has ever used one knows they are famous for giving Gray Water Showers. In addition to a built in pump and gauge they have a tire stem for use with a compressor.

For those who don't know, tennis ball guns can be used for more than just fun. If you slip an old sock over the end of the pipe with a cord attached they make great line throwing guns. Ball goes into sock and pulls cord over tree limb.
 
Well, while asking,, do understand the DOM - by definition - is welded, not seamless

Ugly old ASTM A 106 PIPE IS seamless - by definition.

Its also entirely practical to send it out to someone like Texas Honing and have the 21 foot stick honed to make the bore less lumpy and more round than pipe specs

For what-its-worth department

Note absence of "C" words in this post
 








 
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