Jump scares are a lot of fun, but if you want to hold the attention of all those trick-or-treaters we’d suggest a creepy prop. One of the best choices in that category is a ghoulishly lifelike hand. You can draw some inspiration from this roundup of robot hands which Adafruit put together.
We’ve chosen four examples for the image above but there are more to be had than just these. In the upper left there is a laser-cut acrylic hand that actually features some force sensitive resistors on the fingertips to help implement some haptic feedback. This project was inspired by the hand seen in the lower right which uses flex sensors on a glove to control the bot’s movement. If you’re looking for something more realistic the 3D printed parts on the lower left are the best bet. But if you’re looking to put something together by Halloween night the offering in the upper right is the way to go. It’s hacked together using cardboard templates to cut out plastic parts and using polymorph to form joints and brackets.
We see a lot of projects using Eagle for the schematics and PCB layout. There are a few that use Kicad, but we hear very little about other alternatives. Recently, [Limpkin] has been working with Altium and Cadence and wrote about how they compare when it comes to PCB layout. Neither are free packages so it’s good to know what you’re getting into before taking the plunge.
[Limpkin] begins his overview by mentioning that the schematic editors are comparable; the differences start to show themselves in the PCB layout tools. Here you can see that Altium always labels the pads so you know what net each of them belongs to. Cadence (whose PCB layout tool is called Allegro) will display the net if you hover over the pad with your mouse. Both have 3D rendering, with Altium’s looking a bit more pleasant but what real use is it anyway? Okay, we will admit we love a good photorealistic board rendering, but we digress. The most interesting differences show themselves once traces are all on the board and need to be rejiggered. Cadence will actually move traces on other layers automatically to avoid collision with a via that is late to the party, and Altium shows some strange behavior when dragging traces. [Limpkin] doesn’t register a final judgement, but the comparison alone is worth the read.
There’s something special about improvised weapons built for the upcoming zombie apocalypse. Whether it’s a Lousiville Decapitron or a shotgun revolver, we’re always fascinated by homemade weapons. Here’s a few that rolled into the tip line over the last few weeks:
You call that a knife?
[Joerg Sprave], a.k.a. that German guy on YouTube that has fun with slingshots, built a spinning steak knife saw thing. Basically, it’s eight steak knives attached to a wheel and driven with an electric drill. It’s not a terribly complex build, but it does give off a zombie apocalypse/first person shooter melee weapon vibe.
Battery cannon, because why not
Why use potatoes when you can use D-cell batteries? [CasterTown] on YouTube put together a small propane-powered spud gun that can put a battery through a car door. This isn’t the first time we’ve seen batteries used as ammo, but it’s still an extremely powerful build.
Oh man the 60s were cool.
Back in the 60s, safety wasn’t a huge concern. Any 10-year-old could walk into a dime store and buy Jarts – a game consisting of kids throwing sharp spikes at each other. Also, magazines had descriptions of how to build a freaking mortar in a backyard. Able to make a 20-foot grouping at 1900 feet, this would probably merit a visit from a SWAT team today. Needless to say, don’t try this at home.
Don’t do this. Please.
Last but not least is [Rocketlab] and [SadisticTheory]’s $15 flamethrower. It’s just a gas tank from a 2-stroke engine, a 12 volt battery and a pump. Common sense requires us to mention this build is very,
very illegal (apparently it is legal)and extremely unsafe. Don’t replicate this build.
Actually, we take that back. You shouldn’t build any of these weapons because they’re very dangerous. Just think of these as a neat thing to look at. Let other people hurt themselves. You may complain about how unsafe these weapons are in the comments.
[Daniel] at diybookscanner.org posted a roundup of the best automatic book scanner builds to date. A lot of the comments on our last coverage of book scanners were summed up by [Spork] with, “No automatic page turning = no use.” Turning a page in a book with a robot is really hard, though, and these builds do a really amazing job at automating very tedious work.
First up is [jck57]’s servo actuated auto scanner. From the video, this build is very good and we caught it skipping only one page. Check out the video in action and the overview.
Next up is the Berlin Hackerspace c-base’s vacuum box scanner. The video shows a large diamond-shaped box with a vacuum cleaner hose attached to the top. The box is pressed down into the binding of the book where the vacuum picks up the next page. The build is a manual version of this very expensive machine, but does have the bonus of not poking a centuries-old book with robotic manipulators.
[dtic] was one of the first people to look into automatic page turning. His prototype (video here) uses servos, but has a very simple construction. The downside is that the book can only scan one side of the book at a time; to get other side, the user would have to turn the book upside down and scan it again.
Project Gado was an unsuccessful Kickstarter campaign whose goal was to develop a scanner to archive photos at Johns Hopkins University. The build used a vacuum-powered suction cup to lift pages onto a flatbed scanner. It’s a lot slower than some of the other builds, but we think there would be less of a risk of skipping a page.
As for processing the images captured by a digital camera, [Steve]’s book scan wizard handles a lot of the necessary post processing tasks. Converting everything to a PDF, changing the DPI, and putting all the pages in order can be done with [Steve]’s app. Download here.
Turning a page of a book is a very hard problem – books are designed for hands, not grippers. If you’ve got a book scanner build you’d like to show off, send it in on the tip line. We’ll be sure to put it up.
When the idea of an engine hacks theme was being kicked around at Hack a Day, the subject of rocket engines was one of the first to come up. There was a problem though; solid rocket motors are far too common to be interesting, and even hybrid rocket engines are becoming passé. We’ve never seen a liquid-fuel rocket build before, so that’s what this roundup evolved into.
First up is [Robert Watzlavick], who has been has been building liquid fueled engines for the last decade. He started out with an uncooled kerosene/LOX whose death is seen in the title pic for this post. Lately he’s been working on a monster of an engine that is projected to deliver over 1,000 Newtons of thrust. As with many of the early rockets that launched man into space, [Robert] uses kerosene and liquid oxygen for fuel. This man knows his stuff.
Next up is a ‘kit’ liquid fuel rocket, the SS67B-3, that’s based on the German WWII Taifun missile. This engine is about as basic as you can get. There’s one fuel tank that holds both the Hydrogen Peroxide oxidizer and gasoline fuel. Both are blasted into the combustion chamber with pressurized gas. we found a write-up on this kit with some good pictures, but no video.
If high pressures, glowing metal, and huge flames pique your interest, there’s also a fabulous e-book (PDF warning) available that is a reprint of How to Design, Build and Test Small Liquid-Fuel Rocket Engines by [Leroy J. Krzyck]. This book was originally written in 1967, but lathes and mills haven’t changed that much over the past 44 years. Why not give it a go? There’s still plenty of time to complete the build before the 100th anniversary of Goddard’s first flight.
[Denha’s] been building marble machines for years and decided to look a back on some of his favorite marble-based builds (translated). There’s a slew of them, as well as some thoughts about each. Our favorite part is the digital simulations of the projects. For instance, the image above shows a flip-flop marble machine that was built in a physics simulator. This makes it a lot easier to plan for the physical build as it will tell you exact dimensions before you cut your first piece of material. Both of these images were pulled from videos which can be seen after the break. But this isn’t the most hard-core of pre-build planning. SolidWorks, a CAD suite that is most often used to design 3D models for precision machining, has also been used to model the more intricate machines.
Continue reading “Marble machines roundup”
If you’re an avid Hackaday reader chances are that you immediately recognized [Matthias Wandel’s] name. He’s been featured many many times to go along with his many many talents. Most notably, his ability to do some amazing things with wood. But really, it’s the idea that counts, and he seems to have a duffle bag full of them. [Rachel adn Justin] over at WonderHowTo recently published a full interview with Mattias. In it he shares his thoughts on where some of these ideas come from, how he approaches his projects, and even shares some advice for those just getting started.
This is usually the time where we make a witty remark and try to work in links to feature articles from the past. If we were limited to just one it would be pretty tough (although there’s a special place in our hearts for the wasp sucker). Luckily we’re not limited, so here’s a list of some of [Matthias’] projects which Hackaday covered previously: