Digital Caliper Talks For Accessibility, With This App

August 2, 2020 by Jenny List 37 Comments

A good instrument stays with its owner for a lifetime, becoming part of their essential trusted toolkit to be consulted as a matter of habit. If you use a caliper to measure dimensions you’ll know this, and a quick glance at its scale or digital display will be second nature. But if you aren’t fortunate enough to have the eyesight to see the caliper, then it’s off-limits, and that’s something [Naomi Wu] has addressed with her open-source accessible speaking caliper app. It’s an Android app that connects to digital calipers that contain Bluetooth connectivity, and as well as speaking aloud the caliper reading it also displays it in very large text on the device screen. As well as the source link from which you can build the app, it’s available for installation directly from the Google Play Store.

If you’re used to [Naomi] from her video tours of the electronics businesses in her native Shenzhen, her eye-catching wearable projects, or her exploits with an industrial CNC machine in her living room, you might be interested to know that aside from this app she’s been a long-time proponent of open-source in China. She was responsible among other projects for the Sino:bit educational computer board, which holds the distinction for her of having secured the first ever Chinese OSHWA certification.

You can see the caliper app in action below the break.

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VK-01 Is A Bartender You Don’t Need To Tip

August 1, 2020 by Al Williams 15 Comments

[Donald Bell’s] robotic bartender entry into the 2020 Cocktail Robotics Grand Challenge is one of those things that sounds easy until you start getting into the details. After all, how hard is it to dispense some liquids into a glass? Harder than you might think. Sure there are pumps — [Donald] uses peristaltic pumps — but there’s also two Raspberry Pis, an ESP8622, and at least one more microcontroller lurking underneath. You can see a video about the device below.

Even if you don’t want a refreshing libation, you’ll probably like the VK-01’s Bladerunner cyberpunk styling. What we really enjoyed about the post was that it took you through the concept sketches, some of the design trades, and even a cardboard prototype.

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Playing The Pixelflut

August 1, 2020 by Kerry Scharfglass 7 Comments

Every hacker gathering needs as many pixels as its hackers can get their hands on. Get a group together and you’ll be blinded by the amount of light on display. (We propose “a blinkenlights” as the taxonomic name for such a group.) At a large gathering, what better way to show of your elite hacking ability than a “competition” over who can paint an LED canvas the best? Enter Pixelflut, the multiplayer drawing canvas.

Pixelflut has been around since at least 2012, but it came to this author’s attention after editor [Jenny List] noted it in her review of SHA 2017. What was that beguiling display behind the central bar? It turns out it was a display driven by a server running Pixelflut. A Pixelflut server exposes a display which can be drawn on by sending commands over the network in an extremely simple protocol. There are just four ASCII commands supported by every server — essentially get pixel, set pixel, screen size, and help — so implementing either a client or server is a snap, and that’s sort of the point.

While the original implementations appear to be written by [defnull] at the link at the top, in some sense Pixelflut is more of a common protocol than an implementation. In a sense, one “plays” one of a variety of Pixelflut minigames. When there is a display in a shared space the game is who can control the most area by drawing the fastest, either by being clever or by consuming as much bandwidth as possible.

Then there is the game of who can write the fastest more battle-hardened server possible in order to handle all that traffic without collapsing. To give a sense of scale, one installation at 36c3 reported that a truly gargantuan 0.5 petabytes of data were spent at a peak of rate of more than 30 gigabits/second, just painting pixels! That’s bound to bog down all but the most lithe server implementation. (“Flut” is “flood” in German.)

While hacker camps may be on pause for the foreseeable future, writing a performant Pixelflut client or server seems like an excellent way to sharpen one’s skills while we wait for their return. For a video example check out the embed after the break. Have a favorite implementation? Tell us about it in the comments!

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2020: Everything Is Virtual

August 1, 2020 by Elliot Williams 6 Comments

It’s like the dystopian future arrived out of the blue. From one year to the next we went from holing up in overly air-conditioned hotel ballrooms and actually meeting our fellow meatbags in the flesh, to huddling in our pods and staring at the screens. I’m looking for the taps to hook me in to the Matrix at this point.

But if you haven’t yet received your flying car or your daily Soma ration, you can still take comfort in one thing: all of the hacker conferences are streaming live, as if it were some fantastic cyber-future! In fact, as we type this, someone is telling you how to print your way to free drinks on USAir flights as part of HOPE’s offering, but the talks will continue for the next few days. (Go straight to live stream one.)

If retrocomputing is more your thing, Saturday marks the start of the virtual Vintage Computer Festival West of which Hackaday is a proud sponsor. (Here’s the schedule.)

And next weekend is DEF CON in Safe Mode with Networking. While we can totally imagine how the talks and demo sessions will work, the Villages, informal talks and hack-togethers based on a common theme, will be a real test of distributed conferencing.

OK, I’ll admit it: I really miss getting together with folks and having the truly random conversations that pre-scripted teleconferences just don’t seem to facilitate. Lobbycon suffers in lockdown. But if you’ve never been to any of these events, and you just want a taste of the talks and presentations at least, now’s your chance to get in for free. And if you like what you see, and if the virus lets us, we’ll see you in person next summer!

You’ve Got Rat!

August 1, 2020 by Jenny List 34 Comments

If you home has never been subject to a rodent invasion then you are fortunate. Our world is full of rats and mice, and despite the best efforts of humanity to keep them at bay it is inevitable that a few will find their way through. For [Marius Taciuc] this became a problem, as his traps needed constant checking to avoid the prospect of a festering rat carcass. His solution? A humane trap equipped with an ESP8266, that notifies him when the rodent is incarcerated.

The tech behind it is about as simple as it’s possible to get, the trap’s door activates a switch, that powers on an ESP8266 module. The ESP’s code simply wakes it up, connects to a wireless network, and sends a query to IFTTT with a call to a service that sends him an email alert. There’s no need to monitor any GPIO lines or have any code running to keep an eye on the trap, it’s all purely a function of the power switch.

The trap itself is interesting, in that it’s a home-made one constructed from soldered copper wire. Sadly there are few details of its construction, but you can see more of it including a live rat inside it, in the video below the break. And if making a trap catches your interest, we can help you there.

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Electric Skateboard With Tank Tracks, From A Big 3D Printer

July 31, 2020 by Danie Conradie 4 Comments

One of the basic truths of ground vehicles is that they are always cooler with tank tracks. Maybe not better, but definitely cooler. [Ivan Miranda] takes this to heart, and is arguably the king of 3D printed tank projects on YouTube. He has built a giant 3D printed electric skateboard with tank tracks with the latest version of his giant 3D printer. Videos after the break.

The skateboard consists of a large steel frame, with tracked bogies on either end. Most of the bogie components are 3D printed, including the wheels and tracks, and each bogie is driven by a brushless motor via a belt. Some bends were added to the steel frame with just 3D printed inserts for his bench vice. The bogies are mounted to the frame with a standard skateboard truck, which allows it to steer like a normal skateboard, by tilting the deck. It looks as though this works well on a smooth concrete floor, but we suspect that turning will be harder on rough surface where the tracks can’t slide. We’ll have to wait for the next video for a full field test.

The large components for this skateboard were printed on [Ivan]’s MK3 version of his giant 3D printer. Although it’s very similar to the previous version, improvements were made in key areas. The sliding bed frame’s weight was reduced by almost 50%, and the wheels were rotated, so they ride on top of the extrusion below it, instead of on it’s side, which helps the longevity of the wheels. This also allows bed levelling to be done by turning the eccentric spacers on each of the wheels. The rigidity of base frame and x-axis beam were increased by adding more aluminium extrusions. Although he doesn’t explicitly mention the print volume, it looks to be the same as the previous version, which was 800x500x500. For materials other than PLA, we suspect a heated build chamber will be required have any chance of making big prints without excessive warping.

[Ivan] really likes big prints, with a number of 3D printed tanks, a giant nerf gun, and a sand drawing bot. Continue reading “Electric Skateboard With Tank Tracks, From A Big 3D Printer” →

Producing A Prop Gun That Actually Ejects Cases

July 31, 2020 by Lewin Day 34 Comments

With the movie Man of War shooting in Cyprus, there was a problem. They needed prop guns that looked realistic and ejected cases when fired, but that were also allowed under the country’s firearm laws. The task fell on [Paradym’s] shoulders, and he set to work producing a prop capable of doing the job.

With the laws in Cyprus, using anything off-the-shelf like an Airsoft pistol was simply not allowed. Instead, he had to start from scratch, creating a design outwardly similar to the Colt 1911 to suit the era of the film. Using green gas canisters for power, the first focus was on getting a realistic semi-automatic firing cycle happening. With that done, the next goal was to get the cases to eject from the weapon on each shot. To achieve this, a lever was used, actuated by the slide moving back after a shot, pushing the “spent” cartridge out of the port.

[Paradym] goes into great deal, covering the design of the 3D printed parts, the machining of springs, as well as the final assembly of the prop. We’ve seen other prop gun builds before, too. Video after the break.

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