Rapid-Fire Hail Of Chopstick Arrows Makes Short Work Of Diminutive Foes

Many Hackaday readers may also be familiar with the Discworld series of fantasy novels from [Terry Pratchett], and thus might recognise a weapon referred to as the Piecemaker. A siege crossbow modified to launch a hail of supersonic arrows, it was the favoured sidearm of a troll police officer, and would frequently appear disintegrating large parts of the miscreants’ Evil Lairs to comedic effect.

Just as a non-police-officer walking the streets of Ank-Morpork with a Piecemaker might find swiftly themselves in the Patrician’s scorpion pit, we’re guessing ownership of such a fearsome weapon might earn you a free ride in a police car here on Roundworld. But those of you wishing for just a taste of the arrow-hail action needn’t give up hope, because [Turnah81] has made something close to it on a smaller scale. His array of twelve mousetrap-triggered catapults fires a volley of darts made from wooden kebab skewers in an entertaining fashion, and has enough force to penetrate a sheet of cardboard.

He refers to a previous project with a single dart, and this one is in many respects twelve of that project in an array. But in building it he solves some surprisingly tricky engineering problems, such as matching the power of multiple rubber bands, or creating a linkage capable of triggering twelve mousetraps (almost) in unison. His solution, a system of bent coat-hanger wires actuated by the falling bar of each trap, triggers each successive trap in a near-simultaneous crescendo of arrow firepower.

On one hand this is a project with more than a touch of frivolity about it. But the seriousness with which he approaches it and sorts out its teething troubles makes it an interesting watch, and his testing it as a labour-saving device for common household tasks made us laugh. Take a look, we’ve put the video below the break.

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An Englishman’s Home Is His (Drone-Defended) Castle

Retiring to the garden for a few reflective puffs on the meerschaum and a quick shufti through the Racing Post, and the peace of the afternoon is shattered by the buzz of a drone in the old airspace,what! What’s a chap to do, let loose with both barrels of the finest birdshot from the trusty twelve-bore? Or build a missile battery cunningly concealed in a dovecote? The latter is what [secretbatcave] did to protect his little slice of England, and while we’re not sure of its efficacy we’re still pretty taken with it. After all, who wouldn’t want a useless garden accoutrement that conceals a fearsome 21st century defence system?

The basic shell of the dovecote is made from laser cut ply, in the shape of an innocuous miniature house. The roof is in two sliding sections which glide apart upon servo-controlled drawer runners, and concealed within is the rocket launcher itself on a counterweighted arm to lift it through the opening. The (toy) rocket itelf is aimed with a camera pan/tilt mechanism,and the whole is under the control of a Raspberry Pi

It’s understood that this is a rather tongue-in-cheek project, and the chances of any multirotors falling out of the sky are somewhat remote. But it does serve also to bring a bit of light back onto a theme Hackaday have touched upon in previous years, that of the sometimes uneasy relationship between drone and public.

Add Some Edge To Your Blades With Blown-Arc Plasma

If you polled science fiction fans on what piece of technology portrayed by the movies that they most desire, chances are pretty good that the lightsabers from the Star Wars franchise would be near the top of the list. There’s just something about having that much power in the palm of your hand and still needing to be up close and personal to fight with it. Plus being able to melt holes in bulkheads is pretty keen, as are the cool sounds.

Sadly, the day we can shape and contain plasma in a blade-shaped field is probably pretty far off, but that didn’t stop [Alan Pan] from trying the next best thing: a handheld plasma-projecting blade. He starts with a basic Jacob’s ladder. We’ve seen many of these before, but the basic idea is to ionize the air between two parallel, vertical conductors; the hot plasma heats the air causing it to rise until it reaches the top and snuffs itself out, starting the process over again at the bottom. His twist is to force the plasma into a sheet between the electrodes with air from a leaf blower, forming a blown-arc plasma. That’s pretty cool looking by itself, but he also stretched the electrodes along razor-sharp wood planer blades, for extra danger. We have to admit that the thing looks pretty intimidating, even if the plasma doesn’t really pack bulkhead-melting thermal power. Check out the results in the video below.

We’d love to see [Alan] make good on his promise to make the whole thing self-contained with an electric ducted fan or mini jet engine. Even as it is, it’s still pretty neat. It’s not really his first lightsaber rodeo, but at least this one doesn’t need butane.

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Let No Eyebrow Go Unsinged With A Wrist-Mounted Flamethrower

We’ll say it just once, and right up front: wrist-mounted flamethrowers are a bad idea. An itchy nose and a brief moment of forgetfulness while sporting one of these would make for a Really Bad Day. That said, this flaming gauntlet of doom looks like a lot of fun.

We’ve got to hand it to [Steve Hernandez] – he put a lot of work into the Flame-O-Tron 9000. Building on his prior art in the field, [Steve] went a bit further with this design. The principle is the same – butane plus spark equals fun – but the guts of this flamethrower are entirely new. A pipe bomb custom fuel tank is used rather than the stock butane can, and a solenoid valve controls fuel flow. Everything lives in a snazzy acrylic case that rides on a handmade leather bracer, and controls in the hand grip plus an Arduino allow the user to fire short bursts of flame or charge up for a real fireball. See what you think of the final product in the short video after the break; it sounds as though even if the fuel runs out, the high-voltage would make a dandy stun gun.

Maybe we should lay off the safety nagging on these wrist rockets. After all, we’ve seen many, many, many of them, with nary a report of injury.

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Marines 3D-Print Part to Repair Multi-Million Dollar Fighter

The good news: all you need to complete the repair you’re working on is one small part. The bad news: it’s only available in a larger, expensive assembly. The worst news: shipping time is forever. We’ve all been there, and it’s a hard pill to swallow for the DIYer. Seems like a good use case for 3D-printing.

Now imagine you’re a US Marine, and instead of fixing a dishwasher or TV remote, you’ve got a $123 million F-35 fighter in the shop. The part you need is a small plastic bumper for the landing gear door, but it’s only available as part of the whole door assembly, which costs $70,000 taxpayer dollars. And lead time to get it shipped from the States is measured in weeks. Can you even entertain the notion of 3D-printing a replacement? It turns out you can, and it looks like there will be more additive manufacturing to come in Corps repair depots around the world.

Details of the printed part are not forthcoming for obvious reasons, but the part was modeled in Blender and printed in PETG on what appears to be a consumer-grade printer. The part was installed after a quick approval for airworthiness, and the grounded fighter was back in service within days. It’s encouraging that this is not a one-off; other parts have been approved for flight use by the Marines, and a whole catalog of printable parts for ground vehicles is available too. This is the reality that the 3D printing fiction of Lost in Space builds upon.

And who knows? Maybe there are field-printable parts in the disposable drones the Corps is using for standoff resupply missions.

[via 3D-Printing Industry]

Weaponized Fidget Spinners

Fidget spinners were the hottest new craze at one point, but their 15 minutes of fame has well and truly passed. They’re great for fidgeting, and not a whole lot else. One of the main objectives around their use is to spin them as quickly as possible. After [Sushi Ramen] hurt himself after spinning one up with compressed air, however – a new and dangerous idea came to mind.

What you’re looking at is a fidget spinner sword, powered by compressed air. That alone is somewhat of a blessing, as it prevents this horrifying device from being easily man-portable. Through a breakneck build montage, we see almost fifty fidget spinners (in hyperchrome, no less) mounted to a shaft. The shaft is then attached to a hilt and a plastic line is artfully bent up to deliver compressed air at the pull of a trigger, causing the fidget spinners to rotate at moderate speed.

It’s true that the fidget spinners don’t receive a whole lot of torque from the compressed air and thus most of the damage is done purely by swinging the presumably quite heavy device at fragile glass objects. That said, with nothing ventured, nothing is gained, and we’re always glad to see research and development continuing in the fidget spinner space.

Looking for more effective ways to spin, and spin quickly? Check out this brushless motor setup. Video after the break.

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Welcome to the Internet of Swords

As has been made abundantly clear by the advertising department of essentially every consumer electronics manufacturer on the planet: everything is improved by the addition of sensors and a smartphone companion app. Doesn’t matter if it’s your thermostat or your toilet, you absolutely must know at all times that it’s operating at peak efficiency. But why stop at household gadgets? What better to induct into the Internet of Things than 600 year old samurai weaponry?

Introducing the eKatana by [Carlos Justiniano]: by adding a microcontroller and accelerometer to the handle of a practice sword, it provides data on the motion of the blade as it’s swung. When accuracy and precision counts in competitive Katana exhibitions, a sword that can give you real time feedback on your performance could be a valuable training aid.

The eKatana is powered by an Adafruit Feather 32u4 Bluefruit LE and LSM9DS0 accelerometer module along with a tiny 110 mAh LiPo battery. Bundled together, it makes for a small and unobtrusive package at the base of the sword’s handle. [Carlos] mentions a 3D printed enclosure of some type would be a logical future improvement, though a practice sword that has a hollow handle to hold the electronics is probably the most ideal solution.

A real-time output of sword rotation, pitch, and heading is sent out by the Adafruit Feather over BLE for analysis by a companion smartphone application. For now he just has a running output of the raw data, but [Carlos] envisions a fully realized application that could provide the user with motions to perform and give feedback on their form.

Incidentally this isn’t the first motion-detecting sword we’ve ever covered, but we think this particular incarnation of the concept might have more practical applications.