As it turns out, it’s not feasible to print an entire crossbow yet. But [Dan]’s crossbow build does a good job of leveraging what a 3D printer is good at. Most of the printed parts reside in the crossbow’s trigger group, and the diagrams in the write-up clearly show how the trigger, sear and safety all interact. Particularly nice is the automatic nature of the safety, which is engaged by drawing back the string. We also like the printed spring that keeps the quarrel in place on the bridle, and the Picatinny rail for mounting a scope. Non-printed parts include the aluminum tubes used in the stocks, and the bow itself, a composite design with fiberglass rods inside PVC pipe. The video below shows the crossbow in action, and it looks pretty powerful.
Actually, we’ll partially retract our earlier dismissal of entirely 3D-printed crossbows, but [Dan]’s version is a lot more practical and useful than this model. And for a more traditional crossbow design, check out this entirely hand-made crossbow.
While it may only be able to shoot a few cans right now, we certainly wouldn’t want to be in front of [Jason]’s fully automatic Gauss gun capable of firing 15 steel bolts from its magazine in less than two seconds.
The bolts are fired from the gun with a linear motor. [Jason] is using eight coils along the length of his barrel, each one controlled by an IGBT. These are powered by two 22 Volt 3600mAh LiPo battery packs.
As for the mechanical portion of the build, the bolts fired from this gun are actually 6.5mm nails, cut off and sharpened. These are chambered from a spring-loaded magazine, with each new bolt put into the breech with a small solenoid retracting for an instant. The frame is constructed from a square aluminum tube with additional pieces cut with a hacksaw and bent with an impromptu bench vise brake. If ever there was a person deserving of a bench top shear/brake, [Jason] is the man.
The muzzle velocity of these bolts is about 40 m/s, with a muzzle energy that’s about 3% of a .22 LR round. Not deadly, but more than enough for picking off a few cans and bottles in a garage. You can see the video of this futuristic Gauss machine gun below.
Centuries ago, craftsmen and smiths of all sort spent hundreds of hours crafting a crossbow. From the fine craftsmanship that went into making the bow to the impeccable smithing a windlass requires, a lot of effort went into building a machine of war. Since [Chris] has a 3D printer, he figured he could do just as well as these long-dead craftsmen and fabricate a crossbow in under a day.
What’s really interesting about [Chris]’ crossbow is that it is only a single piece of plastic. The bow is integrated into the stock, and the trigger works by some creative CAD design that takes advantage of the bendability of plastic. The only thing required to shoot a bolt from this crossbow is a piece of string. That, and a few chopsticks.
He won’t be taking part in any sieges, but [Chris]’ weapon is more than capable of shooting a bolt across a room or launching a balsa wood airplane. You can see an example of this after the break.
One thing that always amazes us is the ingenuity displayed by prison inmates, as demonstrated in the tools and weapons they create while under the watchful eye of the law. Unlike most people however, these individuals have nothing but time on their side, which lends to the wide range of implements they inevitably dream up.
[Marc Steinmetz] took some time to photograph a handful of contraband items which were confiscated in various prisons. They range from the relatively benign bed sheet ladder to more sophisticated items such as battery-powered shotguns constructed from iron bedposts. While weaponry and escape aids are the most common prison yard creations, he also came across a DIY toaster, a hidden radio receiver, and one of our favorites – the surveillance bug pictured above, which was used to listen in on guards’ conversations.
While the use of any of these items in a controlled prison environment is questionable at best, it’s still interesting to see what people can hack together with limited resources and a heck of a lot of time.
With the war in Libya raging on, the rebels have turned to anything and everything to help give them the upper hand. Engineers and engineering students have put aside their work and studies to become the architects of the Libyan revolution. In a school playground-cum-weapons facility people from all walks of life work together creating powerful weapons from scrap parts.
[Rajab], the group’s chief weapons engineer, used to drive trucks for a living. Now he is directing his fellow fighters on how best to re purpose scrap materials and recovered military weaponry into effective killing machines. As you can see in the video below, everything is fair game. Their creations range from pickup trucks fitted with recovered fighter jet machine guns, to a Power Wheels chassis that has been converted into a remote controlled machine gun turret.
It’s amazing the things that can be produced with some scrap materials and a bit of ingenuity.
This has been around for a while, but we never covered it – and it’s friggin’ awesome. [jesse] sent in this crusher, but I featured this one due to a sort of draconian copyright notice on the former. The latter also uses some easier to find, hackable parts. They’re both built on similar concepts – use a large bank of capacitors to store up the energy needed, and deliver it in one large pulse to a coil electromagnet. The resulting force lasts for a short time, but is enough to physically crush an aluminum can inward without touching it. Yet another one has some more dramatic examples of crushed cans.