Unusual Tool Gets An Unusual Repair

In today’s value-engineered world, getting a decade of service out of a cordless tool is pretty impressive. By that point you’ve probably gotten your original investment back, and if the tool gives up the ghost, well, that’s what the e-waste bin is for. Not everyone likes to give up so easily, though, which results in clever repairs like the one that brought this cordless driver back to life.

The Black & Decker “Gyrodriver,” an interesting tool that is controlled with a twist of the wrist rather than the push of a button, worked well for [Petteri Aimonen] right up until the main planetary gear train started slipping thanks to stripped teeth on the plastic ring gear. Careful measurements of one of the planetary gears to determine parameters like the pitch and pressure angle of the teeth, along with the tooth count on both the planet gear and the stripped ring.

Here, most of us would have just 3D printed a replacement ring gear, but [Petteri] went a different way. He mentally rolled the ring gear out, envisioning it as a rack gear. To fabricate it, he simply ran a 60° V-bit across a sheet of steel plate, creating 56 parallel grooves with the correct pitch. Wrapping the grooved sheet around a round form created the ring gear while simultaneously closing the angle between teeth enough to match the measured 55° tooth angle in the original. [Petteri] says he soldered the two ends together to form the ring; it looks more like a weld in the photos, but whatever it was, the driver worked well after the old plastic teeth were milled out and the new ring gear was glued in place.

We think this is a really clever way to make gears, which seems like it would work well for both internal and external teeth. There are other ways to do it, of course, but this is one tip we’ll file away for a rainy day.

The ring shown on someone's index finger

The ErgO Ring Makes Computer Interactions Comfortable

[Sophia Dai] brings us a project you will definitely like if you’re tired of traditional peripherals like a typical keyboard and mouse combo. This is ErgO, a smart ring you can build out of a few commonly available breakouts, and it keeps a large number of features within a finger’s reach. The project has got an IMU, a Pimoroni trackball, and a good few buttons to perform actions or switch modes, and it’s powered by a tiny Bluetooth-enabled devboard so it can seamlessly perform HID device duty.

While the hardware itself appears to be in a relatively early state, there’s no shortage of features, and the whole experience looks quite polished. Want to lay back in your chair yet keep scrolling the web, clicking through links as you go? This ring lets you do that, no need to hold your mouse anymore, and you can even use it while exercising. Want to do some quick text editing on the fly? That’s also available; the ErgO is designed to be used for day to day tasks, and the UX is thought out well. Want to use it with more than just your computer? There is a device switching feature. The build instructions are quite respectable, too – you can absolutely build one like this yourself, just get a few breakouts, a small battery, some 3D printed parts, and find an evening to solder them all together. All code is on GitHub, just like you would expect from a hack well done.

Looking for a different sort of ring? We’ve recently featured a hackable cheap smart ring usable for fitness tracking – this one is a product that’s still being reverse-engineered, but it’s alright if you’re okay with only having an accelerometer and a few optical sensors.

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A closeup of the ring, inner electronics including a lit green LED seen through the inner transparent epoxy, next to the official app used to light up the LED for a demo.

New Part Day: A Hackable Smart Ring

We’ve seen prolific firmware hacker [Aaron Christophel] tackle smart devices of all sorts, and he never fails to deliver. This time, he’s exploring a device that seems like it could have come from the pages of a Cyberpunk RPG manual — a shiny chrome Bluetooth Low Energy (BLE) smart ring that’s packed with sensors, is reasonably hacker friendly, and is currently selling for as little as $20.

The ring’s structure is simple — the outside is polished anodized metal, with the electronics and battery carefully laid out along the inside surface, complete with a magnetic charging port. It has a BLE-enabled MCU, a heartrate sensor, and an accelerometer. It’s not much, but you can do a lot with it, from the usual exercise and sleep tracking, to a tap-sensitive interface for anything you want to control from the palm of your hand. In the video’s comments, someone noted how a custom firmware for the ring could be used to detect seizures; a perfect example of how hacking such gadgets can bring someone a brighter future.

The ring manufacturer’s website provides firmware update images, and it turns out, you can upload your own firmware onto it over-the-air through BLE. There’s no signing, no encryption — this is a dream device for your purposes. Even better, the MCU is somewhat well-known. There’s an SDK, for a start, and a datasheet which describes all you would want to know, save for perhaps the tastiest features. It’s got 200 K of RAM, 512 K of flash, BLE library already in ROM, this ring gives you a lot to wield for how little space it all takes up. You can even get access to the chip’s Serial Wire Debug (SWD) pads, though you’ve got to scrape away some epoxy first.

As we’ve seen in the past, once [Aaron] starts hacking on these sort of devices, their popularity tends to skyrocket. We’d recommend ordering a couple now before sellers get wise and start raising prices. While we’ve seen hackers build their own smart rings before, it’s tricky business, and the end results usually have very limited capability. The potential for creating our own firmware for such an affordable and capable device is very exciting — watch this space!

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LED Ring Brings The Bling

We’ve seen our share of light-up jewelry over the years, but for some reason — probably power — it’s almost always earrings or necklaces. So when we saw [ROBO HUB]’s LED ring, we had to check it out. It involves a bit of behind-the-scenes action in the form of a battery holder that you palm, but the end effect is quite cool.

Essentially, this is a 3D printed ring with SMD LEDs painstakingly soldered together in parallel along a pair of thin copper wires. The ring itself is in two parts: a base, and a cover to diffuse and protect the LEDs. A pair of wires run out from the ring and connect to a printed coin cell holder.

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Hackaday Links: March 12, 2023

With a long history of nearly universal hate for their products, you’d think printer manufacturers would by now have found ways to back off from the policies that only seem to keep aggravating customers. But rather than make it a financially wiser decision to throw out a printer and buy a new one than to buy new ink cartridges or toners, manufacturers keep coming up with new and devious ways to piss customers off. Case in point: Hewlett-Packard now seems to be bricking printers with third-party ink cartridges. Reports from users say that a new error message has popped up on screens of printers with non-HP cartridges installed warning that further use of the printer has been blocked. Previously, printers just warned about potential quality issues from non-HP consumables, but now they’re essentially bricked until you cough up the money for legit HP cartridges. Users who have contacted HP support say that they were told the change occurred because of a recent firmware update sent to the printer, so that’s comforting.

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Front Door Keys Hidden In Plain Sight

If there’s one thing about managing a bunch of keys, whether they’re for RSA, SSH, or a car, it’s that large amounts of them can be a hassle. In fact, anything that makes life even a little bit simpler is a concept we often see projects built on to of, and keys are no different. This project, for example, eliminates the need to consciously carry a house key around by hiding it in a piece of jewelry.

This project sprang from [Maxime]’s previous project, which allowed the front door to be unlocked with a smartphone or tablet. This isn’t much better than carrying a key, since the valuable piece of electronics must be toted along in place of one. Instead, this build eschews the smartphone for a ring which can be worn and used to unlock the door with the wave of a hand. The ring contains an RFID which is read by an antenna that’s monitored by a Wemos D1 Mini. When it sees the ring, a set of servos unlocks the door.

The entire device is mounted on the front of the door about where a peephole would normally be, with the mechanical actuators on the inside. It seems just as secure (if not more so) than carrying around a metal key, and we also appreciate the aesthetic of circuit boards shown off in this way, rather than hidden inside an enclosure. It’s an interesting build that reminds us of some other unique ways of unlocking a door.

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Becky Stern, David Cranor, And A CT Scanner Vs The Oura Ring

If you wonder how it’s possible to fit a fitness tracker into a ring, well, you’re not alone. [Becky Stern] sent one off to get CT scanned, went at it with a rotary tool, and then she made a video about it with [David Cranor]. (Video embedded below.)

While it’s super cool that you can do a teardown without tearing anything down these days — thanks to the CT scan — most of the analysis is done on a cut-up version of the thing through a normal stereo microscope. Still, the ability to then flip over to a 3D CT scan of the thing is nice.

We absolutely concur with [Becky] and [David] that it’s astounding how much was fit into very little space. Somewhere along the way, [David] muses that the electrical, mechanical, and software design teams must have all worked tightly together on this project to pull it off, and it shows. All along, there’s a nice running dialog on how you know what you’re looking at when tearing at a new device, and it’s nice to look over their shoulders.

Then there’s the bit where [Becky] shows you what a lithium-ion battery pack looks like when you cut it in half. She says it was already mostly discharged, and she didn’t burst into flames. But take it easy out there! (Also, make sure you take your hot xylene out on the patio.)

X-ray machines are of course just the coolest thing when doing a teardown. We’ve seen them used from fixing multimeters to simply looking at servo motors.

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