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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Magnetic Couplings Make This Lego Submarine Watertight

July 7, 2020 by Dan Maloney 14 Comments

Although you’d be hard-pressed to tell in some areas, it’s summer in the northern hemisphere, which always seems to bring out the projects that require a swimming pool for adequate testing. The [Brick Experiment Channel]’s latest build, a submersible made almost entirely from Lego, is one such project and has us pining for weather that makes a dip sensible rather than suicidal.

The sub featured in the video below is a significant improvement over the “Sub in a Jug” approach the [Brick Experiment Channel] favored for version 1. Rather than starting with a vessel specifically designed not to hold water, the hull for this vessel is an IKEA food container, with a stout glass body and a flexible lid with silicone seals. And instead of penetrating the hull for driveshafts and attempting to seal them, this time around he built clever magnetic couplings.

The couplings transmit torque from the motors on the inside to gears and props on the outside. And where the first version used a syringe-pump ballast tank to control the depth, this one uses vertical thrusters. The flexible lid proved to be a problem with that scheme, since it tended to collapse as the depth increased, preventing the sub from surfacing. That was solved with some Lego bracing and adjustment of the lead shot ballast used to keep the sub neutrally buoyant.

This looks like a ton of summer fun, and even if you don’t have Legos galore to work with, it could easily be adapted to other materials. There are a ton of other fun [BEC] Lego builds to check out, some of which we’ve covered, including a Lego drone and a playing card shooter.

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PCB Jewelry Never Looked So Good

May 16, 2020 by Orlando Hoilett 8 Comments

[Gautchh] wanted to make something nice for his girlfriend. Being the DIY enthusiast he is, he thought a hand-made gift would resonate with her better than something he could pick up from the store. Enter NeckLight, a glow in the dark PCB necklace. He was first inspired by another project he ran across on Instructables, then decided to put his own little spin on the design. It’s cool how that works. Interestingly enough, it was his first time using Fusion 360, but you probably wouldn’t know that if you took a look at the results.

Aside from soldering, the trickiest part of this project was trying to get the LED intensities just right. [Gautchh] found the best way to do this was experimentally by testing each LED color with a series of resistors. He wanted to ensure he could get the color intensity and the LED current just right. Finally, with a touch of acetone, he was done (though he might want to try some alternatives to acetone next time).

[Gautchh] also thinks that this project would be a really nice way for beginners to learn surface mount (SMD) soldering. We’ve seen a few cool SMD LED projects before. Who could forget those competitive soldering challenges over at DEF CON?

Anyway. Thanks, [Gautchh]. We hope your girlfriend, and your dog, enjoyed their gifts.

3D Printed Metro Charger Ready For The Wasteland

December 13, 2019 by Tom Nardi 21 Comments

In the video game Metro 2033 and its subsequent sequels, players fight their way through a post-apocalyptic version of Russia using improvised weapons and tools cobbled together from the sort of bits and bobs the survivors of a nuclear war might be able to scavenge from the rubble. One of the most useful devices in the game is known as the “Universal Charger”: a hand-operated dynamo that the player must use periodically recharge their electrical devices.

Being a fan of the series, [Nikola Petrov] wanted to build his own version of the Metro 2033 charger; but rather than going for an exact screen replica, he decided to explore the mechanism itself and see if he could 3D print a functional device.

As demonstrated in the video after the break, his charger manages to produce enough energy to light an LED on each squeeze of the trigger. Though if we were packing our gear to go fight mutated beasties in alternate-future Moscow, we might look for something with a bit more kick.

Beyond the 3D printed parts, the charger uses a couple short pieces of 8 mm rod, a NEMA 17 stepper motor, and a one-way bearing that’s usually used for pull starting small gasolene engines.

Interestingly, [Nikola Petrov] is no stranger to 3D printed electrical generation. If you’re interested in getting some real power out of a NEMA 17 stepper, his fantastic printed wind turbine is a must-see.

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Tuning Up The ThinkGeek Star Trek Intercom Panel

December 6, 2019 by Tom Nardi 8 Comments

On Star Trek, all Kirk and friends had to do was snap the button on the always conveniently located intercom panel, start talking, and the intended recipient would immediately respond no matter where they were in the ship. How did it work? Who knows. In spite of, or perhaps even because of, the lightly-explained nature of the technology, the cherry-red wall intercoms still hold a certain charm for fans of the groundbreaking show.

A viewer sent [Fran Blanche] a scaled down replica of the intercom from ThinkGeek, and while it certainly looks fairly close to the original prop, it has a couple of annoying design elements. When triggered by the side-mounted motion sensors, the panel will play either the iconic swoosh of the automatic doors or the “Red Alert” sound effect. It’s a cute idea for a kid’s bedroom maybe, but not exactly ideal for somebody who regularly records YouTube videos.

So the first order of business was to cut the motion sensors out of the circuit and replace them with a push button. [Fran] draws up a quick diagram to explain how these sensors work, and shows that they can easily be bypassed with a momentary switch since they normally bring the line high when triggered. She then converted the indicator light on the right side of the panel into a button to enable the alert sound effect, which is more accurate to how it worked in the show anyway.

The other issue, and perhaps the most egregious to Star Trek fans, is that the “Red Alert” indicator on the top of the panel didn’t actually flash like it did in the show. To design and build this panel and not put a few LEDs behind that piece of frosted plastic seems a bit like producing a Matchbox car and forgetting to make the wheels spin. With a couple of red LEDs and a bit of new wiring, the oversight was quickly rectified.

While it might not be perfect, at least ThinkGeek actually produced a functional product this time. It could have ended up like one of their April Fool’s “products” that never get put into production, forcing a desperate Trekkie to begrudgingly build his own version.

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A Bootable Greeting For The Xenomorph In Your Life

October 7, 2019 by Tom Nardi 4 Comments

When he needed a gift for his Alien superfan friend, [Stephen Brennan] decided the best way to put his unique set of skills to use would be to create a bootable Linux operating system that captures the sights and sounds of the Nostromo’s retro-futuristic computer systems. We could all use a friend like that.

Even if would never occur to you gift somebody a bootable flash drive, there’s a wealth of information in this blog post about Linux customization which could be useful for all sorts of projects. From creating a bootsplash image to automatically starting up a minimalistic windowing environment so a single graphical application takes center stage.

Whether you’re looking to tweak your desktop machine or build a Raspberry Pi kiosk, the commands and tips that [Stephen] shows off are sure to be interesting for anyone who’s not quite satisfied with how their Linux distribution of choice looks “out of the box”.

But there’s more to this project than a custom wallpaper and some retro fonts. [Stephen] actually took the time to create a facsimile of the “Personal Terminal” computer interface shown in the recent Alien: Isolation game in C using ncurses. The resulting program, aptly named “alien-console”, is released under the BSD license and is flexible enough that you could either use it as a base to build your own cyberpunk UI, or just load it up with custom text files and use it on your cyberdeck as-is.

Finally, to really sell the Alien feel, [Stephen] went through and ripped various audio clips from the film and wove them into the OS so it would make the movie-appropriate boops and beeps. He even included a track of the Nostromo’s ambient engine noise for proper immersion. But perhaps our favorite trick is the use of the sleep command to artificially slow down the terminal and give everything a bit more “weight”. After all, flying a pretend starship should feel like serious business.

A PKE Meter That Actually Detects Radiation

July 24, 2019 by Lewin Day 5 Comments

Fans of Ghostbusters will remember the PKE meter, a winged handheld device capable of detecting supernatural activity. Precious little technical data on the device remains, leaving us unable to replicate its functionality. However, the flashing, spreading wings serve as a strong visual indicator of danger, and [mosivers] decided this would be perfect for a Geiger counter build.

An SBM20 Geiger tube serves as the detection device, hooked up to an Arduino Nano. An OLED display is used to display the numerical data to the user. The enclosure and folding wings are 3D printed, and fitted with 80s-style yellow LEDs as per the original movie prop.

The device is quite intuitive in its use – if the wings flare out and the lights are flashing faster, you’re detecting an increased level of radiation. In a very real sense, it makes using a Geiger counter much more straightforward for the inexperienced or the hearing impaired. Naturally, there’s also a buzzer generating the foreboding clicks as you’d expect, too.

Geiger counters are a popular project, though we hope they don’t become common household items in the near future. Here’s a Fallout-inspired build for fans of the game. Video after the break.

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