3-DOF Robot Arm Wrist Without The Motor Weight

November 3, 2022 by 15 Comments

A major challenge of robotic arms is the weight of the actuators, especially closer to the end of the arm. The long lever arm means more torque is required from the other actuators, and everything flexes a bit more. To get around this, [RoTechnic] moved the wrist stepper motors off the arms entirely.

He built a push-pull mechanism that uses braided fishing line to transfer motion to the robot arm’s wrist using Bowden tubes. The motors are mounted on the arm’s base, with a drum and two lengths of fishing line on the shafts. The lines pass through an adjustable tensioner before entering the Bowden tubes. This drum mechanism is also present on each of the three rotating axes of the wrist.

[RoTechnic] used an Arduino-powered RAMPS board as a controller, which is programmed to accept over the serial interface. He created a simple GUI and scripting interface in Jupyter Labs to generate and send command, which seems like an excellent solution for testing.

We can see this mechanism being a useful for a variety of motion applications, and definitely something to add to the idea toolbox. It is somewhat similar to some other cable-operated joints we’ve seen in humanoid robots and other 3D printed arms.

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M.2 For Hackers – Connectors

November 3, 2022 by 10 Comments

In the first M.2 article, I’ve described real-world types and usecases of M.2 devices, so that you don’t get confused when dealing with various cards and ports available out there. I’ve also designed quite a few M.2 cards and card-accepting adapters myself. And today, I’d like to tell you everything you need to know in order to build M.2 tech on your own.

There’s two sides to building with M.2 – adding M.2 sockets onto your PCBs, and building the PCBs that are M.2 cards. I’ll cover both of these, starting with the former, and knowing how to deal with M.2 sockets might be the only thing you ever need. Apart from what I’ll be describing, there’s some decent guides you can learn bits and pieces from, like the Sparkfun MicroMod design guide, most of which is MicroMod-specific but includes quite a few M.2 tips and tricks too.

First, Let’s Talk About The Y-Key

What could you do with a M.2 socket on your PCB? For a start, many tasty hobbyist-friendly SoMs and CPUs now have a PCIe interface accessible, and if you’re building a development board or a simple breakout, an M.2 socket will let you connect an NVMe SSD for all your high-speed low-power storage needs – many Raspberry Pi Compute Module mainboards have M.2 M-key sockets specifically for that, and there’s NVMe support in the RPi firmware to boot. Plus, you can always plug a full-sized PCIe adapter or an extender into such a socket and connect a PCIe network card or other much-needed device – even perhaps, an external GPU! However, as much as PCIe-equipped SoMs are tasty, they’re far from the only reason to use M.2 sockets.

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Infrastructure diagram of [Stefan]'s network at the end of his fiber optics journey

Say No To Obsolescence, Wire Up Your House With Fiber

November 3, 2022 by 105 Comments

These days, if you wire your house with anything less than gigabit, you might end up throttling your Internet connection. If you wired things up using two pairs per device back in 100BASE-T days, however, you’ll want to redo your cabling before you buy new switches. Now, some of us are already starting to equip ourselves with 2.5G hardware — which may require new cabling once again. Would you like to opt out of the Ethernet cabling upgrade rat race, at least for a while? Do like [Stefan Schüller] did, and use fiber optics for your home networking needs!

[Stefan] walks you through everything you’d need to know if you ever choose to look into fiber for your networking needs, and explains the design decisions he’s made — from splicing fiber optics himself, to building a PC to do routing instead of getting a hardware Small Form-factor Pluggable (SFP) equipped router. He also describes pitfalls, like SFP modules requiring reconfiguration to work with different router brands, and having to buy a fiber splicer with an eye-watering pricetag.

In the end, he shows a cost breakdown, and says he’s quite happy with the upgrade. While the costs might seem prohibitive compared to running Ethernet, upgrading to fiber will have your equipment function at top speed whenever you need it – who knows, perhaps in a few years time, 2.5G will no longer suffice for new advancements in home technology needs, and we’ll see more SFP modules in hackers’ hands. After all, modern TVs already use fiber optics for video data transfer.

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MoCA Networking Is A Niche Solution For Coax Lovers

November 3, 2022 by 63 Comments

When it comes to networking these days, the vast majority of our devices are connected wirelessly. Beyond that, we’re all familiar with the Cat 5 and Cat 6 cables that form the high-capacity Ethernet networks in our homes, schools, and offices.

It’s only if you go back to the very dawn of Ethernet that coaxial cables are relevant… right? Wrong! MoCA networking is all about coaxial cables, designed to hook up devices over cable TV infrastructure!

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End Of An Era, As LEGO To Discontinue Mindstorms

November 3, 2022 by 46 Comments

When there are so many single board computers and other products aimed at providing children with the means to learn about programming and other skills, it is easy to forget at time before the Arduino or the Raspberry Pi and their imitators, when a computer was very much an expensive closed box.

Into this late-’90s vacuum left in the wake of the 8-bit home computer revolution came LEGO’s Mindstorms kits, a box of interlocking goodies with a special programmable brick, which gave kids the chance to make free-form computerized robotic projects all of their own. The recent news that after 24 years the company will discontinue the Mindstorms range at the end of the year thus feels like the end of an era to anyone who has ridden the accessible microcontroller train since then.

What became Mindstorms has its roots in the MIT Media Lab’s Programmable Brick project, a series of chunky LEGO bricks with microcontrollers and the Mindstorms LEGO brick contacts for motors and sensors. Their Logo programming language implementation was eschewed by LEGO in favor of a graphical system on a host computer, and the Mindstorms kit was born. The brand has since been used on a series of iterations of the controller, and a range of different robotics kits.

In 1998, a home computer had morphed from something programmable in BASIC to a machine that ran Windows and Microsoft Office. Boards such as Parallax’s BASIC Stamp were available but expensive, and didn’t come with anything to control. The Mindstorms kit was revolutionary then in offering an accessible fully programmable microcontroller in a toy, along with a full set of LEGO including motors and sensors to use with it.

We’re guessing Mindstorms has been seen off by better and cheaper single board computers here in 2022, but that doesn’t take away its special place in providing ’90s kids with their first chance to make a proper robot their way. The kits have found their place here at Hackaday, but perhaps most of the projects we’ve featured using them being a few years old now underlines why they are to meet their end. So long Mindstorms, you won’t be forgotten!

Header image: Mairi, (CC BY-SA 3.0).

Heirloom Knife Will Carve Pumpkins For Years To Come

November 3, 2022 by 6 Comments

Halloween may be behind us, but that just means that we’ve reached the best time to buy pumpkins. After all, it’s still fall, and there are pies to be made and tables to be decorated. Why should carved-up pumpkins be restricted to spooky season?

The only problem is that it’s 2022, and we’re still expected to use those terrible little serrated knives to carve our pumpkins. Those orange-handled garbage ‘knives’ are hardly suited to cut the lid, much less carve any of the intricate designs that come in the little booklet. So what’s a pumpkin-carving enthusiast to do? If you’re [XYZ Create], you make your own out of walnut, maple, and a gently-used jigsaw blade that’s still way sharp enough to tear through pumpkin flesh.

[XYZ Create] started with a nice chunk of walnut, which he split lengthwise in order to insert the blade, which sits in a cavity within a thin piece of maple. Once [XYZ Create] had the handle ready to go, he inserted the jigsaw blade and epoxied the sandwich together. After sanding down the edges to make a comfortable grip, he finished off the build by rubbing a bit of carving board wax into the handle. Check out the build video after the break.

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Roll The Radioactive Dice For Truly Random D&D Play

November 2, 2022 by 22 Comments

When you have a bunch of people gathered around a table for a “Dungeons & Dragons” session, you have to expect that things are not always going to go smoothly. After all, people who willingly create and immerse themselves in an alternate reality where one bad roll of the dice can lead to the virtual death of a character they’ve spent months or years with can be traumatic. And with that trauma comes the search for the guilty — it’s the dice! It’s always the dice!

Eliminating that excuse, or at least making it statistically implausible, is the idea behind this radioactively random dice roller. It comes to us from [Science Shack] and uses radioactive decay to generate truly random numbers, as opposed to the pseudorandom number generators baked into most microcontrollers. The design is based on [AlphaPhoenix]’s muon-powered RNG, but with a significant twist: rather than depending on background radiation, [Science Shack] brought the power of uranium to the party.

They obtained a sample of autunite, a weird-looking phosphate mineral that contains a decent amount of uranium, perfect for stimulating the Geiger counter built into the dice roller. Autunite also has the advantage of looking very cool under UV light, taking on a ghostly “fuel rod glow,” in the [Homer Simpson] sense. The decay-powered RNG at the heart of this build is used to simulate throws of every standard D&D die, from a D4 to a D100. The laser-cut hardboard case holds all the controls and displays, and also has some strategically placed openings to gaze upon its glowing guts.

We really like the design, but we have to quibble with the handling of the uranium ore; true, the specific activity of autunite is probably pretty low, but it seems like at least some gloves would have been in order.

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