Thread 64229510

So my son and his friends want to build a potato canon over the course of a few weekends. Do you guys have

1) Any warnings against it or general advice on their legality in the US?

2) A bill of materials needed to build it assuming it clears question 1?

3)Any specific advice on fuels and projectiles to achieve dertain effects?

Big pipe. End cap. Stuff if full of improvised napalm. Point your face directly into the barrel as you light it.

>>64229510 (OP)
They aren't firearms according to the ATF so you have nothing to worry about under federal law--ATF even mentions this on their website.
State/local laws vary, some places don't give a fuck, some places will rape you.

general tips/advice:
Starting ether is the best fuel and leaves the least residue. You need far less fuel than you think. A very short spray is all you need--like as short as you can possibly depress the button. A lot of people think more fuel = more bang but it is very easy to get an overly rich mixture and that makes less power. You'll figure it out real fast.
Use proper gluing technique with primer and fresh glue, you don't want it coming apart in your face. Make sure you're using proper pressure-rated pipe, ideally SCH80 but SCH40 works too. Do NOT use "DVW" pipe, that is much thinner and is not safe.

>projectiles
potatoes are classic. They're cheap, they're biodegradable.. But you can shoot nearly anything out of one using rags as a wad.

>>64229560
Suggestions on ignition system?

>>64229510 (OP)
wrap that thing with a fuckload of fiberglass repair wrap along the sides
if it blows up, you want it going out the front & back, not the side of the shooter's head
>>64229569
use a taser, good reliable arcs

>>64229510 (OP)
We used to take turns and make someone stand 75 yards away with a lacrosse net and try to catch the potatos

Backyard Ballistics is a great book that covers how to make a few different types of spud guns as well as some other fun and slightly dangerous stuff you should buy it

>>64229569
For cheap ignition, you can use the piezoelectric ignition from one of those long candle lighters.

>>64229715
>candle lighter
literally complete garbage
an actual piezoelectric bbq igniter is better, but you're still going to be left clicking it for a minute straight if the fuel mix isn't perfect

>>64229569
I used a piezo unit from a gas grill. you can make a simple trigger grip by mounting it with PVC fittings.
The main part is a 3/4" PVC cross fitting. The gas grill piezo unit will fit right into it, run the wires out the back. Use a piece of 3/4 PVC for the handle, and a plug at the top to attach it. Run screws up through the plug into a small board, you can then use hose clamps to attach this to the rest of it.

>>64229704
Another good one that used to circulate at gun shows was called "vegetable artillery for fun and revolution"

>>64229510 (OP)
A guy in my neighborhood killed himself with one when I was maybe 15. He put too much gas in it or it had a weak point or and other point of failure and died from shrapnel penetrating his heart in front of his kids and friends.

They're usually safe, just be careful man.

>>64229798
I used two 2" steel screws and a grill igniter, and never had a problem with ignition. One click and boom! I used hairspray, spray deodorant, card cleaner, etc. All lit off on the first click. Like the other anon said, hairspray and deodorant would gum up the threads on the pipe cap, if you let it set, and didn't open it often, or clean them. Just use 3" pipe for the combustion chamber, and 2" for the barrel. Make the volume of the barrel 2x that of the combustion chamber. Don't forget to file the end of you barrel to a knife edge so that it automatically cuts the potato to the exact inner diameter of your barrel. So, get a 3" pipe 12" long, a 2" pipe 27" long, a 3" threaded end cap, and a 3" to 2" reduction coupler, two 1.5"-2" brass screws, some glue and primer. Make sure your cuts are straight, and use a file or 280 grit sand paper to scuff up the section of pipe that will be your glue joint for mechanical adhesion. Dry fit your pipes, make how far the pipe is inside the couple's, and them sand them, clean them with a rag and alcohol, prime them and allow it to dry, apply glue, and insert the pipe twisting it a quarter turn as you push it in. Once you bottom out, hold it for around 30 seconds to allow the air to escape from the glue joint and start to set up. You can figure out the rest.

>>64229894
>make how far the pipe is inside the couple's
mark how far the pipe goes inside the couplers*

>>64229671
>>64229510 (OP)
Potato guns. You just spray hairspray in the bottom there and then hit it with these barbeque lighters and a fսckkng potato will shoot out of there about 400 mph. Shot myself in the face by accident one time, they really fuckin hurt

https://www.youtube.com/watch?v=8UcJDBBO6iM

https://www.amazon.com/Backyard-Ballistics-Cannons-Cincinnati-Dynamite/dp/1613740646/ref=sr_1_1?adgrpid=1228155558971059&dib=eyJ2IjoiMSJ9.cBd1G3kmcuiinUnhaynIx37mL5gPSz9kwKzxGJVaSbmOuHRoTCT5AHFodBOawZzrkF8ATuB6BEbUrk8qBWZvxtpxIejEnqJy2R5Vje1WyFxLtTyKJybTUMb0_GSBXip7fy2eKuVHv7mLkylv1tNIlNNVI5o2jy2DRse5pj7oVprKNyIKnqvtSwvaAOsby5PpkZCWfOK5xclmIqqAwg7WfsyUVSqntVe9qWgjNDLRrbc.KSmu6j0S8JneDzXuRH-cjJa2GSk8rRHR8d-e9dqMmqA&dib_tag=se&hvadid=76759855603356&hvbmt=be&hvdev=c&hvlocphy=73516&hvnetw=s&hvqmt=e&hvtargid=kwd-76760063871481%3Aloc-190&hydadcr=14131_13496246&keywords=book+backyard+ballistics&mcid=7763ec82080637008c34197372d7760f&msclkid=fc9fba16bb0114d85877d2ab53a0c6c7&qid=1757276326&sr=8-1
Use the manual. Be safe. Have fun.

>grown-ass man
>doesn't even know how to make a potato gun

PotatoGun on a budget
- Buy a outer reamer chamfer tool. Can get it for <$20 at walmert. Use it to sharpen the tube so you can just shove a too-large spud down the pipe and it automatically cuts to a perfect fit.
- NEVER store in sunlight. PVC gets brittle with sun.
- Wrap a protective layer around the ignition chamber. I’m partial to reinforced packing tape (the stuff with the thread). You can get a 3-pack for $20.
- Do NOT use DWV pipe even though it’s cheaper. It’s super thin waste-water pipe, for non-pressurized use only.
- By volume barrel-to-chamber ratio should be no more than 2:1, no less than 1.5:1. Keep a wooden broomstick on hand to clear the inevitable misfire. Never forget a spud in the barrel, they get nasty.

>>64229510 (OP)
Why not start smaller and safer first with a compressed air cannon? You'll only need a soda bottle for the pressure chamber, a Schrader valve for the feeding, a ball valve as the trigger and a pump to... well... pump. Once you get bored of throwing random things into the air you can move on to designing gliders with foldable wings that pop up once released and take advantage of the upcoming autumn thermal winds. Just trim one aileron/rudder and have it spin in circles back down to you.

>>64229569
use the ignitor module from a gas grill

>>64230096
>Shot myself in the face by accident
Found the statistical retard.

>>64231089
>grown-ass man doesn't even know how to edit the cookie suffix from links

>>64231699
Traditional, but a pain in the ass. Get a grill lighter from the dollar store and take all the butane and tubes out of it, keeping the piezoelectric module and wiring in the convenient trigger package.

Also, hairspray is shit because it gums everything up after a while, including the ignition contacts. Gasoline in a body spray bottle is the way to go, the sprayer aerosolizes it pretty well.

>>64231735
>WHOOSH

>>64229510 (OP)
>1) Any warnings against it or general advice on their legality in the US?
The only way you're getting busted for a potato cannon is if you're doing something incredibly stupid with it and get caught. The key is to not get caught.
>2) A bill of materials needed to build it assuming it clears question 1?
Depends on your design. Me and my buddies growing up had several with varying degrees of complexity. PVC which is pressure rated and sealant is what most people use to build them.
>3)Any specific advice on fuels and projectiles to achieve dertain effects?
Hairspray sucks as fuel. In terms of projectiles we would shoot everything and we successfully made a cannon capable of launching a firebomb (albeit weak) a good distance.

>>64231306
>Why not start smaller and safer first with a compressed air cannon?
Don't be a fucking pussy.

>>64230096
You could have died. I've seen Pumpkins and Melons getting ripped open by harder "Ammo." Plus, they can become actual firearms if you use something better than hairspray.

Use ABS pipe or at the bare minimum, pressure rated PVC. ABS is better because IF it does explode, it just cracks and the pressure shoots out the crack, instead of into a million sharp pieces like PVC. Buy some ABS/PVC sealant, put a small amount around all the ends of pipes that will be glued to other pipes. Buy an electric grill sparker, the generic kind with the red button. Then you will just have two wires that you need to drill two small holes into the ignition chamber to thread them through. Circumcise the ends of the two wires so that they are exposed metal wires and give them about a quarter inch gap between them. When you click the red button you'll see a good sized strong spark. If you don't see a spark, bend them closer. Use something cheap like Aquanet hairspray, axe body spray or similar. It will be plenty powerful enough to launch a potato a quarter mile or more. Wait 24 hours for the ABS/PVC sealant to cure and test fire it with socks first. The further you stuff your projectile down the barrel, the more powerful, high pressure, and louder it will be. So DO NOT start with a potato shoved all the way down the barrel, that shit will sound like a 12 gauge and possibly explode if you fucked up construction. What's fun is a golf ball inside a sock, or rocks in a sock.
Unscrew the back end cap, spray for about 1 second long, screw the end cap back on quickly and press the red button.
>t. Have made over 10 potato guns in size from larger than the OP image to small handguns all using the same method

>>64233452
>Buy some ABS/PVC sealant
You want 'pipe cement' not sealant. Some dumb motherfucker is going to read your instructions, use caulk instead of glue, and then have the damn thing blow up.

>>64229510 (OP)
I don't remember where I read this or maybe saw it on YouTube (probably 10+ years ago), but don't be a cheap motherfucker and try to use old pipe. The old stuff is a lot less ductile than the new stuff from aging and it can shatter spectacularly which is not something you want to happen. At least this was the case with PVC. Though maybe look into ABS like >>64233452 said. Frankly I wouldn't feel comfortable with over-the-shoulder at my neck (where all your arteries are) and would probably throw an old bulletproof vest or two on my shoulder if I DID end up going that route (try a local gun show for source of piles of those things).

>>64231085
>dat fuggin link
Holy shit anon, look at the the god damn trackers on that thing! All you need here:
https://www.amazon.com/Backyard-Ballistics-Cannons-Cincinnati-Dynamite/dp/1613740646

>>64229510 (OP)
Purely theoretical, but can you make a full-power firearm using the same principles as a spud gun?
You can have an electronic direct injector spray bipropellant mixture into the chamber and spark it when you press the trigger. The magazine would contain bare projectiles.

>>64229510 (OP)
>1) Any warnings against it or general advice on their legality in the US?
Yeah, don't build one like a bazooka like in that pic. You don't want that fucking thing next to your head, make it hip fired like a normal human being.

>>64229569
I used a cheap taser module I bought on ebay from china. turns 2AA into a big ass spark. Way more effective than the propane grill igniters I used in the past.

>>64231306
Compressed air potato guns are significantly more expensive and complex to build. You have to build a shuttle valve or whatever it is called, and you use a small ball valve to trigger the big shuttle valve. You COULD use a big ball valve but they're very expensive and hard to turn quickly.

>>64233738
>The old stuff
Yeah, UV exposure makes it brittle.

>>64233747
Yes, people have done that. Some of the "pumkin chunkin" cannons use oxygen + propane dispensed through solenoid valves, or gasoline sprayed with an automotive fuel injector

All these retard /k/ommandos and not one mention of sealing in a coffee can as part of the blast chamber for extra explosive resistance, it’s like none of you actually built potato cannons.

>>64233839
If you want to reinforce it why woudl you do something stupid like that instead of just getting better pipe from the get-go, or fiberglassing or taping it up afterward, which is significantly safer as there is no possibility of metal shrapnel.

It's funny so many replies on here say hairspray is one of the worst choices for propellant, VO5 is/was the most reliable fuel I could find with my experimenting. My potato gun is pretty old, at this point, reinforcing with packing tape is a good idea

>>64229851
Exact same thing happened where I grew up.

>>64233738
I wondered what was up with that link. I will figure out how to avoid trackers.

>>64233747
You can actually exceed firearm velocities with a fuel-air or fuel-oxidizer detonation. Firearms need to be compact, be ready to fire instantly and a lot of things a single shot spudgun doesn't worry about.

Light gas guns are the fastest because they use an explosion to crush a cylinder of light molar weight gas which can expand much faster.

>>64233839
Nobody does this because it's pointless. It would have to be a slip fit cemented in place to have any structural value at all. I've never seen this, not in at least a half dozen potato guns I've seen in person built by others over the years. Not even on the potato gun gun boards of forums that existed decades ago.

>>64234343
+1, VO5 and Aquanet are the best and cheapest and I've used everything since I was a kid

>>64233839
Never seen this either because it's retarded. Coffee cans are not pressure rated and ABS/PVC pipes are. That's dumb

>>64236652
There might be an extension to auto remove them but I just do it manually which is fine at home. Bitch and a half on a phone, though, which sucks when you're out somewhere trying to reply to someone with a link before a thread dies (yes I have an unhealthy forum addiction how can you tell?). Most links should be pretty obvious. Some are harder but for the sites you use the most you gain a sixth sense for. Youtube link trackers are anything "?si=" and after, though it seems that it has a way of choosing which videos get a tracker attached I don't yet understand. Can be a bitch when you also want the timestamp included ("&t=##" where t is equal to the timestamp in seconds, so a minute thirty would be &t=90). Amazon it's anything after /dp/##########. Ebay it's anything after /itm/############ starting with the question mark. Trackers on other sites are pretty easy to spot but it can be a pain to figure out their link formatting. Usually anything like "&hash=" or "&your+search+terms+used+to+find+this+item" (sometimes separated by "%20" or IIRC underscores) are pretty common and easy to spot.

Also trackers make links fucking massive lol. I wonder what that looks like on mobile.

No one mentions to put a screw where the combustion chamber and barrel meet so you have a stop for the potato when you use a broomstick as a ramrod

>>64235923
Apparently pretty common. Shit was sad, dude had like 4 kids under 18. It happened in front of like 10 kids, imagine watching your dad die in front of you from a fucking potato cannon.