The world of warfare was revolutionized by the development of black powder, fireworks, cannons, and the like. You don’t need any of that chemical nonsense to just have fun, though, as this compressed air cannon from [OtisLiu153] demonstrates.
The build uses PVC pipes for both the barrel and the air tank. In the case of the latter, avoiding over-pressurization is key to avoiding injury, though some will say you should simply never build a PVC pipe pressure vessel at all. In this case, [OtisLiu153] strictly recommends 150 psi as a limit, which is nicely within the 280 PSI rating of the 2″ Schedule 40 PVC being used. Though, as they note, the connections in the design aren’t necessarily up to the same rating.
Off-the-shelf couplings are used to piece everything together, with the twin-reservoir design also acting as a useful shoulder mount. Charging the cannon is done via a Schrader valve, as you might find on a bike’s inner tube, and firing is achieved via a ball valve.
Of course, if you build such an air cannon yourself, just be careful with your aim. Video after the break.
Continue reading “Building A Simple Compressed Air Cannon Is Easy”
For a happy weekend away in early September, I joined a few of my continental friends for the NewLine event organised by Hackerspace Gent in Belgium. You may have seen some of the resulting write-ups here, and for me the trip is as memorable for the relaxing weekend break it gave me in a mediaeval city as it is for the content of the talks and demonstrations. We took full advantage of the warm weather to have some meals out on café terraces, and it was on the way to one of them that my interest was captured by something unexpected. There at the end of the street was a cannon, not the normal-size cannon you’ll see tastefully arranged around historical military sites the world over, but a truly massive weapon. I had stumbled upon Dulle Griet, one of very few surviving super-sized 15th century siege cannons. It even had a familiar feel to it, being a sister to the very similar Mons Meg at Edinburgh Castle in Scotland.
Continue reading “Retrotechtacular: This 15th-Century Siege Cannon Might Kill You Instead Of The Target”
One of our favorite things about Halloween is the sheer number of hacks that come out of it each year. This year, hacking is almost a requirement to keep things physically distanced, but that doesn’t mean we can’t have fun. You want fun? How about a candy cannon that launches sweet projectiles at trick-or-treaters from fifty feet?
[Paul McCabe]’s cannon uses a sprinkler valve and an air compressor to launch a pair of fun size candy bars, each encased in a film canister shell. Each trick-or-treater stomps a foot switch fifty feet away at the end of the driveway, and as long as someone is there holding down the primary ignition, the cannon will fire with a nice retort that sounds like a large wind instrument playing a D note.
We were sad to learn that the parachute idea didn’t shake out, but the glow sticks are a great addition for night time. Check out the demo after the break, which is followed by a build video and then some more launches for the fun of it. Don’t have enough time to build a cannon of this caliber? You could put a spooky six-foot slide together pretty quickly.
Continue reading “Trick Or Yeet Cannon Will Give Them Candy Shell Shock”
[MJKZZ] sends in this entertaining little tutorial on building a small automated cannon out of a syringe.
He starts the build off by modifying an arc lighter, the fancy kind one might use to light a fire on a windy day, so that it can be controlled by a micro-controller. The arc is moved to the needle end of the syringe with a careful application of wires and hot glue. When the syringe is filled with a bit of alcohol and the original plunger is pressed back in a small spark will send it flying back out in a very satisfying fashion.
Of course it wouldn’t be a proper hack without an Arduino added on for no reason other than the joy of doing so. [MKJZZ] adds an ultrasonic sensor into the mix which, when triggered appropriately by an invading object fires the arc lighter using a reed relay.
He demonstrates the build by eliminating an intruding coke can on his work bench. You can see it in the video after the break. All in all a very fun hack.
Continue reading “Death To All Coca Cola Cans With This Miniature Arduino Powered Cannon”
Casting metal at home is somewhat tricky, but there’s no denying the results can be quite rewarding. [FarmCraft101] put his incredible craftsmanship on display, and learned a few new things in the process, by scratch building a scale replica bronze cannon and carriage.
Starting with a sufficient quantity of scrap metal, he first produced bronze ingots. Getting the actual casting right took multiples attempts. First tried a lost foam cast, which failed miserably, but provided a sample metal which was put through tensile strength testing. The second attempt was done using a wood barrel form and a split mold, and was cast horizontally which resulted in shrinkage on top of the barrel. The third attempt, arranged vertically, almost resulted in a high risk game of “the floor is lava”, with molten bronze pouring out across his garage floor after the mold split open during casting.
Attempt number four was finally successful, again using a vertical mold but with more sturdy clamping. This roughcast barrel was then drilled out and finished to a beautiful mirror with the help of a lathe and a lot of elbow grease. He then turned his attention to the carriage, which itself is a real beauty featuring custom wagon wheels with a charred wood finish and linseed oil coating.
You can check out the build video after the break, but we’ll warn you now, [FarmCraft101] never actually fires this gorgeous creation. If you’d like to try your hand at DIY cannoneering and have a 3D printer, you might want to give lost PLA casting a try, or go into mass production with some DIY silicone molds.
Continue reading “Making A Bronze Cannon From Scratch”
We’ve seen backyard casting, and for the most part, we know what’s going on. You make a frame out of plywood or two by fours, get some sand, pack it down, and very carefully make a mold around a pattern. This is something else entirely. [FarmCraft101] is casting a bronze cannon. Sure, it’s scaled down a bit, but this is the very limit of what sanity would dictate a single person can cast out of molten metal.
This attempt at casting a cannon is more or less what you would expect from a backyard bronze casting experiment. There’s a wooden flask and a greensand mold, everything is tamped down well and there’s a liberal coating of talcum powder inside. This is a large casting, though, and this presented a problem: during the pour, the halves of the flask were only held together with a few c-clamps. This ended poorly, with molten bronze pushing against the mold and eventually flowing onto the garage floor. Doing this alone was perhaps a bad idea.
The failure of the mold meant some math was necessary, and after some quick calculations it was found that more than 300 pounds pushing the sides of the mold apart. A second pour, with the sides of the flask bound together with nylon straps, was much more successful with a good looking bronze cannon ready for some abuse with a wire wheel.
This is only the first video in the series, with the next videos covering the machining and boring out of the barrel. That’s some serious craft right there.
Continue reading “Casting A Cannon Is A Lot Harder Than You Think”
Water is a stable chemical, but with the addition of a little electricity, it can be split into its component parts. The result is just the right mix of H2 and O2 to convert back into water with a bang. [Peter Sripol] has built a charming desktop cannon in just such a way.
The build consists of a contact lens canister filled with a solution of water and potassium hydroxide. By running a DC current through this solution, oxyhydrogen is produced, which then passes through a flash arrestor and into a combustion chamber. Upon the chamber is affixed a rocket, which is propelled when the charge is lit by a piezoelectric ignitor.
The chemical side of the build was easy, but it took significant experimentation to get the rocket side of things working well. Eventually success was found by creating a blast cap out of paper and hot glue which allowed the energy of the blast to be more effectively transferred to the rocket body. With this in place, the cannon is capable of firing small paper rockets in excess of 20 feet.
With the brass and copper components mounted upon stained wood, this contraption would look beautiful on any desk and would be great for assailing one’s fellow coworkers. If your office doesn’t have an explosives policy yet, once you bring this in to work, it will soon. [Peter] uses similar technology in his Nerf blasters, too. Video after the break.
Continue reading “Hydrogen Desk Cannon Is Fun With Electricity And Water”