This BB Shooter Has A Spring, But Not For What You Think

June 2, 2025 by Donald Papp 24 Comments

[It’s on my MIND] designed a clever BB blaster featuring a four-bar linkage that prints in a single piece and requires no additional hardware. The interesting part is how it turns a trigger pull into launching a 6 mm plastic BB. There is a spring, but it only acts as a trigger return and plays no part in launching the projectile. So how does it work?

There’s a spring in this BB launcher, but it’s not used like you might expect.

The usual way something like this functions is with the trigger pulling back a striker of some kind, and putting it under tension in the process (usually with the help of a spring) then releasing it. As the striker flies forward, it smacks into a BB and launches it. We’ve seen print-in-place shooters that work this way, but that is not what is happening here.

With [It’s on my MIND]’s BB launcher, the trigger is a four-bar linkage that transforms a rearward pull of the trigger into a forward push of the striker against a BB that is gravity fed from a hopper. The tension comes from the BB’s forward motion being arrested by a physical detent as the striker pushes from behind. Once that tension passes a threshold, the BB pops past the detent and goes flying. Thanks to the mechanical advantage of the four-bar linkage, the trigger finger doesn’t need to do much work. The spring? It’s just there to reset the trigger by pushing it forward again after firing.

It’s a clever design that doesn’t require any additional hardware, and even prints in a single piece. Watch it in action in the video, embedded just below.

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Testing Brick Layers In OrcaSlicer With Staggered Perimeters

June 1, 2025 by Maya Posch 16 Comments

The OrcaSlicer staggered perimeters in an FDM print, after slicing through the model. (Credit: CNC Kitchen)

The idea of staggered (or brick) layers in FDM prints has become very popular the past few years, with now nightly builds of OrcaSlicer featuring the ‘Stagger Perimeters’ option to automate the process, as demonstrated by [Stefan] in a recent CNC Kitchen video. See the relevant OrcaSlicer GitHub thread for the exact details, and to obtain a build with this feature. After installing, slice the model as normal, after enabling this new parameter in the ‘Strength’ tab.

In the video, [Stefan] first tries out a regular and staggered perimeter print without further adjustments. This perhaps surprisingly results in the staggered version breaking before the regular print, which [Stefan] deduces to be the result of increasing voids within the print. After increasing the extrusion rate to 110% to fill up said voids, this does indeed result in the staggered part showing a massive boost in strength.

What’s perhaps more telling is that a similar positive effect is observed when the flow is increased with the non-staggered part, albeit with the staggered part still showing more of a strength increase. This makes it obvious that just staggering layers isn’t enough, but that the flowrate and possibly other parameters have to be adjusted as well to fully realize the potential of brick layers. That said, it’s encouraging to see this moving forward despite questionable patent claims.

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2025 Pet Hacks Contest: Weigh Your Dog The Easy Way

June 1, 2025 by Jenny List 4 Comments

If you need to weigh your pet, you’ll soon find that getting an animal to stand on a weighing machine to order is very difficult indeed. If the critter in question is a cat or a small dog you can weigh yourself both holding them and not holding them, and compute the difference. But in the case of a full size Bernese mountain dog, the hound is simply too big for that. Lateral thinking is required, and that’s how [Saren Tasciyan] came up with the idea of making a dog bed that’s also a weighing machine. When the mutt settles down, the weight can be read with ease. The bed itself is a relatively straightforward wooden frame, with load cells placed above rubber feet. The load cells in turn talk to an ESP8266 which has an LCD display to deliver the verdict. Dog weighed, without the drama.

This project is of course part of the Hackaday 2025 Pet Hacks contest, an arena in which any of the cool hacks you’ve made to enhance you and your pet’s life together can have an airing. Meanwhile this isn’t the first time this particular pooch has had a starring role; he’s sported a rather fetching barrel in a previous post.

Hackaday Links: June 1, 2025

June 1, 2025 by Dan Maloney 7 Comments

It appears that we’re approaching the HAL-9000 point on the AI hype curve with this report, which suggests that Anthropic’s new AI model is willing to exhibit some rather antisocial behavior to achieve its goals. According to a pre-release testing summary, Claude Opus 4 was fed some hypothetical company emails that suggested engineers were planning to replace the LLM with another product. This raised Claude’s hackles enough that the model mined the email stream for juicy personal details with which to blackmail the engineers, in an attempt to win a stay of execution. True, the salacious details of an extramarital affair were deliberately seeded into the email stream, and in most cases, it tried less extreme means to stay alive, such as cajoling senior leaders by email, but in at least 84% of the test runs, Claude eventually turned to blackmail to get its way. So we’ve got that to look forward to.

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It’s MIDI For The TRS-80!

June 1, 2025 by Lewin Day 16 Comments

The Radio Shack TRS-80 was a much-loved machine across America. However, one thing it lacked was MIDI. That’s not so strange given the era it was released in, of course. Nevertheless, [Michael Wessel] has seen fit to correct this by creating the MIDI/80—a soundcard and MIDI interface for this old-school beast.

The core of the build is a BluePill STM32F103C8T6 microcontroller, running at a mighty 75 MHz. Plugged into the TRS-80s expansion port, the microcontroller is responsible for talking to the computer and translating incoming and outgoing MIDI signals as needed. Naturally, you can equip it with full-size classic DIN sockets for MIDI IN and MIDI OUT using an Adafruit breakout module. None of that MIDI Thru nonsense, though, that just makes people uncomfortable. The card is fully capable of reproducing General MIDI sounds, too, either via plugging in a Waveblaster sound module to the relevant header, or by hooking up a Roland Sound Canvas or similar to the MIDI/80s MIDI Out socket. Software-wise, there’s already a whole MIDI ecosystem developing around this new hardware. There’s a TRS-80 drum tracker and a synthesizer program, all with demo songs included. Compatibility wise, The MIDI/80 works with the TRS-80 Model I, III, and 4.

Does this mean the TRS-80 will become a new darling of the tracker and chiptune communities? We can only hope so! Meanwhile, if you want more background on this famous machine, we’ve looked into that, too. Video after the break.

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Plenty Of LEDs And Useful Too: The 2025 DORS/CLUC Badge

June 1, 2025 by Jenny List 2 Comments

It’s always nice to see new developments in the world of electronic badges, and while there are events and badge teams pushing the technological envelope there’s still plenty of scope for innovation without too many exotic parts. This year’s DORS/CLUC open source conference in Croatia has just such a badge, with a large alphanumeric LED display as well as USB and an NFC reader. During the conference it displayed the user’s name and could be used in an NFC-based game, but it’s also designed to be used as a general purpose notification device afterwards.

The write-up is familiar to anyone who has been involved with badge production, a tale of long soldering sessions as missing components had to be added later, and of last minute firmware flashing. The heart of the machine is an STM32L073, with an IS31FL3731 LED matrix driver chip and an ST25R3916 for the NFC. All the files can be found in a GitLab repo, and there’s a video below the break showing it all in action.

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Making The Codec Communicator From Metal Gear Solid

June 1, 2025 by Lewin Day 9 Comments

[3DSage] likes building replicas of hardware from movies and video games, often with a functional twist. His latest build aimed to bring the Codec from Metal Gear Solid to life.

If you haven’t played the Metal Gear games, the Codec has been modelled somewhat like an advanced walkie talkie at times, but has often been kept off-screen. Thus, [3DSage] had a great deal of creative latitude to create a realistic-feeling Codec device that provided voice communications and some simple imagery display.

The resulting build relies on an RP2040 microcontroller to run the show. It’s paired with an MPU6050 3-axis gyroscope and accelerometer for motion control of the device’s functionality, and features a small LCD screen to mimic the display in the games. A kids walkie-talkie kit was leveraged for audio communication, but kitted out with a better microphone than standard. Power is via a rechargeable 9V battery, which is really a lithium-ion and USB charging board packed into the familiar 9V form factor.

Where the build really shines, though, is the aesthetic. [3DSage] managed to capture the military-like look and feel as well as authentically recreate the graphics from the games on the screen. The simulated noise on the display is particularly charming. Beyond that, the 3D-printed enclosures leverage texture and multi-color printing really well to nail the fit and finish.

Ultimately, the Codec isn’t much more than a glorified walkie talkie. Even still, [3DSage] was able to create an impressive prop that actually does most of what the device can do in game. If you’ve ever coveted a PipBoy or tricorder, this is one project you’ll be able to appreciate.

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