Instead of using a ball valve or other such contrivance to dump air directly from a reservoir into the chamber of this PVC air cannon, [Ben] is using a much more clever design. This is a barrel sealing PVC air cannon, with a moving piston sealed against a rubber hose clamp in the barrel. Adding air through the fill valve moves the piston forward, allowing air to leak into the reservoir. The air supply is then disconnected, and the trigger released causing the piston to move backward. This releases all the air in the reservoir into the barrel instantaneously, resulting in faster ping pong balls and potatoes.
The original trigger for this high power PVC air cannon used a simple ball valve for the trigger. [Ben] didn’t like this solution – it was hard to open and somewhat unergonomic. The ball valve trigger has since been replaced with a valve from a sprinkler system, giving this high power PVC air cannon a fancy brass trigger. It looks awesome, and can kill a watermelon from twenty yards. What more could you want in a high power PVC air cannon?
You can check out the videos for this build – including a guide for the clever piston valve – below.
Hey guys, I was thinking about building a HIGH POWER PVC AIR CANNON, and wondered if anyone had any advice about safety considerations?
Face mask, gloves, heavy coat, earplugs, safety goggle, firehose-style pants, first-aid kit, cell phone with emergency number ready for dialing…
The fundamental NRA HaD rules for safe HIGH POWER PVC AIR CANNON handling are: ALWAYS Keep The HIGH POWER PVC AIR CANNON Pointed In A Safe Direction. This is the primary rule of HIGH POWER PVC AIR CANNON safety. Common sense dictates the safest direction, depending on different circumstances.
When holding a HIGH POWER PVC AIR CANNON, rest your finger alongside the frame and outside the trigger guard. Until you are actually ready to fire, do not touch the trigger. (Valve/piston assembly, whatever)
Store HIGH POWER PVC AIR CANNON(s) so they are not accessible to unauthorized persons. (This is very important, don’t let some kid walk over and blow up his face.) It is your dangerous device, not anyone else’s.
WARNING, use of HIGH POWER PVC AIR CANNON, has been found by the State of California to cause disassociative glee, endorphin rush, and sudden corporeal dismemberment in lab rats.
First thing I thought of, it should be made out of ABS in case of catastrophic failure. PVC is quite hard and will shatter. ABS is spun and has directional filaments, in case of a catastrophic failure it would be much safer as it would want to split and not shatter.
I built one of these about 20 years ago with fibreglass wrapped schedule 80 PVC and an 8-foot Barrel that could put in a inch and a half piece of ice through a 4×6 using a quick release valve. Initial testing was with three quarter inch oak plywood. It went straight through that, the siding and plywood of the garage, and put a dent in my car.
Daren Schwenke So who did you murder with the sniper rifle? Ice is the classic mystery murder weapon. Never mind no statute of limitations on murder.
*quick exhaust Quick release is generally reserved for the type of non-threaded connections used to connect tools to an air supply. Butterfly valves are common in industry but fairly expensive for pneumatic launchers. Especially given how easy it is to cast an epoxy/polyester piston or lathe down some delrin.
You’re right, quick exhaust. A Fernco 3in pipe cap (rubber) works well up to about 100psi. Higher than that the pressure differential caused it to oscillate and not release fully.
I also built a shotgun style loading system for a smaller version and eventually a potato chain gun capable of emptying my 60 gallon air compressor in 30 seconds. Sadly this is all before the age of YouTube.
It’s a clean enough build but there’s nothing special about the design. Barrel and chamber sealing piston valves have been commonplace for quite a while, as have porting sprinkler valves to use as actuators. At this point in time this is the equivalent of getting an arduino to blink an LED With a little tuning the blowgun he uses to trigger the sprinkler valve is enough to unseat the piston. A coaxial diaphragm design makes it much easier to use a blowgun alone and also cuts down on the BOM since you don’t need the T junction.
Yep. Coaxial also let’s l you also use a much higher pressure. None of the the elbows or T joints are actually rated for pressure. By the end I was running CO2 at 200psi and still had a 2:1 safety factor. On my website at the time, I said: “PVC doesn’t show up that we’ll on an Xray, so please be careful.”
This title is total click-bait for the PVC safety police. I’m assuming you’re just going with the “more comments = more ad revenue”.
I’d like an official Hackaday PVC Safety Police badge. I feel that I’ve earned it. But don’t actually make the badge out of PVC, for safety reasons.
Benchoff, trolling, again. If he hates the place so much I dunno why he doesn’t find a job his skills and personality are better suited to.
Actually, you’ll note I played this one straight. I’m not explicitly trolling the PVC Safety Police in this one. This post stands in contrast to the dozen other PVC potato gun posts where I call out the safety police. Here, it’s just a basic, ‘man builds PVC cannon, uses a neat valve, videos below’, and still the PVC safety police come.
I could have mentioned the only death related to a PVC air cannon is a stupid kid that decided to fill it with gunpowder. The injuries on the OSHA reports relating to pressurized PVC are idiots banging pipe with a hammer or welding right next to it. But I didn’t. I didn’t need to troll the Hackaday audience. The PVC Safety Police is the natural state of Hackaday comments.
WARNING- there is PVC rated to take pressurized liquid. There is no PVC that can be pressurized safely with gas. The failure mode of PVC pressurized with liquid is acceptable, the failure mode of PVC pressurized with a gas such as air is lethal. We never cared about this until we had a PVC air cannon fail and seriously injure someone. learn from our mistakes. when it fails with liquid it breaks open and makes a mess, when it fails with gas it bursts and sends plastic frags at high speed into human flesh.
That’s why you pressure test first with water, at 2x your intended gas fill pressure. Had a couple fail the water test (which is mostly harmless), due to using elbows and tees in early designs. Also, give the finished product a good thick coat of duct tape. Helps to protect from impact damage and maybe, catch some shrapnel.
Passing a pressure test just means it won’t fail right away. Plastic changes over time and the stresses put on it by repeated pressure cycles also changes it. We ran our gun at 100 psi for a long time. it failed at 60 psi. Duct tape? I’m willing to bet that is simply a wild guess. Is there anyone who had one blow and say “wow good thing it was wrapped in duct tape!” There is no precedent for such a statement. I’m not trying to be a buzz kill here, I’m just telling you what happened to us. I’m not putting air in PVC pipe anymore.
Chris Krug Sounds like the plastic pipe bomb. Never use plastic bottles when making Molotov cocktails Never mix Ammonia and Bleach. Finally ALWAYS sit behind the driver, because in an accident the driver swerves to protect genderless descriptor.
A better idea would be to build a vacuum canon instead. Yes they do take longer to prepare for fire, but they are easy to build, and won’t turn into a grenade if you screw up. A 1-4 inch PVC pipe, a good vacuum pump, some aluminium foil for the ends, an appropriate quick release hose attachment, and a properly sized projectile.
And if you are really ambitious you can engineer one that can launch a projectile at or above the speed of sound.
I wish this had an upvote button, cause your comment deserves one. For reference: http://www.discovery.com/tv-shows/mythbusters/videos/mythbusters-supersonic-ping-pong-videos/
This reminds me of my childhood! My dad loves to build things out of PVC pipe. I think it’s so much fun. An air cannon would be so cool to have. I bet you could do so many fun things with it.
I have an air canon made from roughly 10.5 feet of of 1.75 in. PVC that drops down to a 3 foot long half inch copper barrel that will put one of the blue and orange Nerf clip system darts, unmodified mind you, 1-2 foot ball field lengths at 50 psi. I need to test it with the new accustrike darts and test it at the max 110 psi my compressor can handle.
My skepticism is triggered by the thought that that’s a feat equivalent to managing to throw a downy feather across an average living room…. i.e. so little momentum that air resistance saps it rapidly.
I what the equation is and the resultant psi, but 50 psi in an 1.75 in diameter housing increases significantly when forced our of a half into hole.
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