Casting A Cannon Is A Lot Harder Than You Think

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.

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Hydrogen Desk Cannon Is Fun With Electricity And Water

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.

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Fire. Vortex. Cannon. Need We Say More?

Tornadoes are a rightfully feared natural disaster. Fire tornadoes are an especially odious event to contend with — on top of whatever else is burning. But, a fire vortex cannon? That’s some awesome eye candy.

The madman behind this cannon belching huge gouts of fire is none other than Youtuber [JAIRUS OF ALL]. This build is actually an upgrade to one of his previous projects — a fire tornado gun that burned itself out and is now twice-revived — and is arguably better at creating a proper vortex to direct the flames. Built around a modified NERF gun, a pair of 60mm electric ducted fans with some additional venting — and tunable via a speed controller — direct the airflow through slits in a vortex chamber. A backpack of liquid propane literally fuels this phoenix of a flamethrower, so [JAIRUS] had plenty of time to put together some great footage. Check it out!

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Propane-Powered Plasma Rifle

It may not be a “phased plasma rifle in the 40-watt range,” and it doesn’t even use plasma in the strict definition, but it’s pretty cool nonetheless. It’s a propane-powered bottle-launching rifle, and it looks like a lot of fun.

[NighthawkInLight] sure likes things that go pop, like his watermelon-wasting air-powered cannon and cheesy-poof pop gun. This one has a little more oomph to it, powered as it is by a propane torch. The principle is simple: fill a soda bottle with propane, ignite the gas, fun ensues. The details are a little more subtle, though, and allowances need to be made to keep back pressure from preventing the projectile from filling with fuel. [NighthawkInLight] overcomes this with some clever machining of the barrel. The final production version in the video below is needlessly but delightfully complex, with a wooden stock and a coil of clear vinyl tubing helical plasma accumulator before the barrel; the last bit is just for show, and we have to admit that it looks pretty good.

Unless you count the pro tip on using CPVC pipe to make custom fittings, this one is nothing but fun. But we don’t have a problem with that.

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DIY Air Cannon Snags Drones From The Sky

Who hasn’t had the experience of a pesky drone buzzing around that family picnic, or hovering over a suburban backyard where bikini-clad daughters are trying to sunbathe in peace? A shotgun used to suffice for such occasions, but with this compressed-air powered drone catcher, there’s no need to worry about illegally discharging a firearm to secure some privacy.

Before the comment line lights up with outrage, the above scenarios are presented entirely in jest. We do not condone the use of force on a drone, nor do we look favorably on those who use drones in a way that even hints at an invasion of privacy. We can all get along, and even though we hope [Make It Extreme]’s anti-drone gun will never be used in anger, it’s still a neat build that gives us lots of ideas. The rig is essentially four coaxial narrow-bore compressed-air cannons, each launching a slug attached to the corner of a lightweight net. A fairly complex set of linkages sets the spread of the barrels, and a pair of old oxygen tanks serve as reservoirs for the compressed air. A fast-acting dump valve is tripped by an interesting trigger mechanism mounted to a complicated stock and grip; we’d have liked to see more on the fabrication of that bit. The video below shows a test firing that results in a clean takedown of a drone, although we doubt the owner of the quad would characterize it as such.

This build is a bit of a departure from [Make It Extreme]’s usual fare of DIY tools like a shop-built vise or big belt sander, or their unusual vehicles like an off-road hoverboard. But it’s always great to watch a good fabrication video, no matter what the subject.

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Tesla Coil Powered Film Canister Gatling Gun

What do you get when you combine a Tesla coil, 315 film canisters and a fortune wheel? The answer is of course a film canister Gatling gun. [ScienceBob] has taken the simple film canister cannon hack to a whole new level. The idea is simple, the film canister has a lid that fits tight and allows pressure to build up, so if you fill it with alcohol vapor and ignite it with a spark gap, you get a small explosion that sends the can flying  away.

[ScienceBob] uses 21 rows of fifteen canisters each around the wheel. There is a spark gap for each canister, and all the spark gaps in the same row are in series. You need a lot of volts to turn on fifteen spark gaps, and that is why the Tesla coil is part of the game. When the outer end of the wire in one row passes near the Tesla coil, a spark jumps and fires all the spark gaps, igniting the alcohol vapor and fifteen cans are expelled from the wheel. The wheel rotates until all rows are fired.

While this nice piece of artillery is sure a lot of fun to fire, but don’t ask us to reload it! If you want more power, check this Gatling gun that fires crossbow bolts, or the Gatling water pistol.

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Weaponizing Elementary Science Experiments

[austiwawa] was playing around with one of those simple linear motors people build as friendly little science experiments. There’s an AA battery in the middle of a set of magnets. When you put it inside of a spring it zips around inside until you run out of spring or magic pixies in the battery.

Of course, the natural question arose, “How do I make it go fast!? Like fast!” After making explosion and woosh noises for a bit (like any good hacker would) he settled down and asked a more specific question. If I made the coil the barrel of an air gun, and then shot the battery out… would it go faster?

So, he built an air cannon. It took some ingenuity and duct tape, but he managed to line the barrel with a copper coil. After that he built an experimental set-up, because making something dangerous is only okay if it’s science. That’s the difference between sensible adults and children.

He shot three “dead” rounds through the cannon, and got a baseline result. These dead rounds were made so by placing the magnets at the improper polarity to forego the motion-boosting properties. Then he shot three live ones through. It went measurably faster! Neat!

What’s the silliest thing you’ve ever seen properly characterized? Let us know in the comments below.

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