Simple 3D Printed Robotic Arm Uses Compliant Mechanism

Learning through play is effective for humans of all ages, and since 2016 [slantconcepts] has been designing STEM kits that help teach kids to build their future overlords. They are launching version 3 of their LittleArm robotic arm, and the progression from version 1 is an interesting study in simplification and parts count reduction without sacrificing functionality.

In all of the LittleArm versions the main mechanical components are 3D printed, and driven by 3 servos for motion plus one additional servo to run the gripper. These kits are specifically intended to be built and disassembled repeatedly, and classrooms are a great place for small screws to easily disappear, so reducing the number of screws was a big goal for v3. The gripper/forearm shows the most dramatic improvement from the previous versions, being simplified from 8 separate components to a single 3D printed part by using a compliant mechanism — that squiggly pattern that allows the gripper to flex into place. The gripper tips also feature a simple “cutout” that allow it more easily grasp horizontal objects.

An Arduino Nano based expansion board is used to control the arm, with a HC-06 Bluetooth module to allow it to be controlled via a smart phone app. Various sensors can also be added to expand the kit’s capabilities. Unfortunately the mechanical design is not open source, but it can still be a source of inspiration for your own design projects.

Hopefully this kit will inspire some future hackers to build a more advanced 3D printed version, or even a giant hydraulic powered arm.

C#, The Language For All Platforms – Now Including Windows 3.11 And DOS

The Microsoft .NET framework has been with us in one form or another since the millennium, and though it has remained largely the preserve of the Microsoft universe, it has found its way since then through a variety of implementations to other platforms including MacOS and GNU/Linux. In Microsoft terms though its history goes back only as far as Windows 98, earlier MS operating systems remain off-limits.

Just a glimmer of .NET in DOS and Windows 3.11 comes courtesy of [Michal Strehovsk√Ĺ], who has successfully compiled .net C# code for both Windows 3.11 and DOS. An in-depth explanation comes courtesy of [Scott Hanselman], and it involves some tricks spanning the decades since the early 1990s. The .NET Core compiler’s object files can be fed into the linker that shipped with an ancient version of Microsoft’s C++ compiler, which when used with Microsoft’s Win32s compatibility layer that brought some of Windos NT’s APIs to the 16-bit OS, allows C# from 2020 to run as though it were 1992 again. Meanwhile the DOS version uses .NET Core’s ability to produce self-contained executables along with some very significant tricks to pare down the size of the finished program from many megabytes to an eventual DOS-suitable 27k. Remember the apocryphal Bill Gates quote, that “640k should be enough for anyone“, that refers to the maximum memory available to DOS without extra memory-extending tricks.

Neither piece of software is especially useful, and we can’t see a rush of C# coders to these new platforms. But we applaud him for his ingenuity, and getting old hardware to do new tricks is right up our alley. It’s certainly dredged up a few memories from back in the day for us. Meanwhile we’ve featured .NET in a few projects over the years, most recently on an FPGA.

Hackaday Links: February 9, 2020

In case you thought that we learned everything we need to know to land on the Moon fifty years ago, think again. NASA still has a lot of questions, and has scheduled the first of many commercial missions designed to fill in the blanks. As part of the Artemis program, which aims to land the first women and the next men on the Moon by 2024, NASA’s Commercial Lunar Payload Service (CLPS) will send 16 science payloads to the Moon via two separate commercial flights. The two companies, Astrobotics and Intuitive Machines, will send landers to the Moon in 2021 using a ULA Vulcan Centaur and a SpaceX Falcon 9, respectively. Fourteen companies were selected for CLPS, and with much to learn (or relearn) about landing and working on the Moon, watch for many more flights in the years to come. We’re all for the commercialization of space, but we have to admit that things were easier to keep track of when space exploration was a little more monolithic.

It looks like millions of BlackBerry phone users will have to find something else to do with their thumbs now that TCL is getting out of the BlackBerry business. The Chinese company announced this week that they would no longer have the rights to manufacture BlackBerry-branded phones like the Key2 as of August 31, 2020. Crackberry addicts were understandably upset, but all may not be lost for those who can’t stand the virtual keyboards on most other smartphones, as there’s still a chance another manufacturer will step in to fill the void.

Hypothetical situation: You’re in need of a car, so you go to a used car dealer. You see a nice car, take it for a test drive, and decide to buy it. Money is exchanged, paperwork done, and the salesman hands you the keys. You go out to the lot to drive your new ride home only to find out that the mechanic has removed the tires. When you ask what the deal is, the salesman says, “Sorry, you didn’t buy a license for the tires.” Hypothetical perhaps, but not far off from what happened to one Tesla Model S buyer when an over-the-air update disabled the Enhanced Autopilot and Full Self-Driving features he paid for. Tesla didn’t see it that way, though, claiming that he’d need to pony up to use the new features, which originally sold for $8,000. It raises interesting questions about how the secondary automotive market will respond to the increasingly complicated relationship between hardware and software, and what you’re actually paying for when you buy a car.

Back in the early days of Bitcoin, skeptics used to dismiss the cryptocurrency by saying, “When you can pay your taxes with it, then it’s real money.” Well, that day is apparently here for the municipality of Zermatt in Switzerland, where it was announced that Bitcoin will be accepted as payment for local taxes and other official fees. The Zermatt city hall has installed a Bitcoin point-of-sale terminal, or payments can be made directly from a Bitcoin wallet after filling out the proper paperwork. Bitcoin as legal tender for public debts is not exactly new; Ohio was doing it back as far as 2018. But we find the economic implications of this interesting — as our resident econometrician [Elliot Williams] pointed out, paying taxes in anything but the national currency was considered preposterous not that long ago.

Why Settle For The Standard Catan Board?

Let’s face it, game night can get downright rowdy. Whether your game nights involve wine and cats, beer and dogs, or vodka and bear cubs, things happen. Maybe the robber gets batted irretrievably far under the couch, or someone gesticulates wildly and spills wine all over your sheep. [EEEEEEEEEDEN]’s gatherings were getting way out of hand, and it was time to design a custom Catan board.

But she didn’t stop with the board tiles — this is Catan redesigned from the ground up, including the pieces, the resource cards, and a custom storage box. [EEEEEEEEEDEN] even planned for player expansion by designing a leaf to drop in the middle. There are a few hundred magnets built into the frame, so there shouldn’t be any more lost pieces. And as far as liquor-proofing all the cardboard goes, [EEEEEEEEEDEN] designed new board tiles and cards, laser cut them from acrylic, and painstakingly painted them all with Plasti-Dip spray.

We think it’s gorgeous, but understand that maybe this minimalist style isn’t for everyone. If you want to go custom, it’s hard to argue against the beauty of 3D Catan.

Thanks to [Johannes] for the tip! via /r/DIY

Sort The Rainbow With An Algorithm Machine

When you’re trying to learn how an algorithm works, it’s not always easy to visualize what’s going on. Well, except for maybe binary sort, thanks to the phone book. Professor [thatguyer] is a computer science teacher who wanted a way to help his students visualize the process of algorithms and at the same time, get a grasp on their resource cost.

The Algorithm Machine can demonstrate 8 different search and sort algorithms using two 100-count strips of RGB LEDs — one to represent an array of integers, and one to create indicators pointing to the integers under scrutiny.

This functional beauty is totally interactive, too. Once the user chooses the values and the algorithm and starts the process, they can speed it up or slow it down with the rotary encoder, or pause to discuss and start again with that slick triangular play button. We particularly like the control button wiring harness [thatguyer] created to keep everything neat and hot-swappable.

This iteration uses 3D printed face plates to give the LEDs shape, but in an early version, [thatguyer] cut and sanded a ton of circles out of brass tubing, and folded as many triangles cut from disposable baking pans. The world could use more teachers as committed as [thatguyer]. This really seems like a handy teaching aid for these concepts, and we wish we’d had one in class to play around with. Here’s your algorithm for watching the demo: click break, press play, enjoy.

If you’re still confused, there are other ways to understand algorithms through visualization. Failing all that, just watch these Hungarian folk dancers work out various algo-rhythms.

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Rental Home Thermostat Gets Smart Upgrade Without Modifying The Dumb Controller

A problem facing those who live in rental properties comes with two prongs: that such properties rarely have up-to-date facilities such as heating controllers, and that landlords tend to take a dim view of tenants installing their own alternatives. [Andy] wanted to upgrade the heating controller in his home and was in this situation, so he came up with a smart controller add-on for the existing mechanical timer that does not irreversibly modify anything and is easily removable when he moves on.

This sounds like an impossible task, but it’s one he’s done very well by mounting a stepper motor on a 3D-printed frame over the timer switch. It’s the type with a motorised ring onto which plastic fingers can be placed to flip a switch on or off; he’s simply removed the plastic fingers and designed a shaft extension for the motor that simulates their passing the switch. He can now turn his heating on and off at will from an ESP8266, in this case on an Adafruit Feather Huzzah.

Behind it all lies Adafruit IO with a custom dashboard — Hackaday’s [Sean Boyce] took this service for a trial run if you’d like his take on it’s features. For this project, Adafruit IO delivered exactly what [Andy] was after but still left a few teething troubles. The stepper needed to be told not to try to hold its position, and moving a stepper very slowly generated wait periods long enough to trigger the ESP’s watchdog timers. Adding in IFTTT gave him the ability to schedule, as well as Alexa control. All in all he’s replicated some commercial offerings with a lot less cost and all without annoying his landlord. You can see it in action in the video below the break.

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See In The Dark, The Simple Way

Night vision googles used to be the exclusive preserve of the military, and then of the well-heeled. Image intensifier tubes were very expensive, and needed high-voltage power supplies to keep them going. Now that we have solid-state infra-red cameras the task of seeing in the dark had become much simpler, and [Alex Zidros] is here to show us just how easy that can be. His night vision goggles take a selection of off-the-shelf parts and a little bit of 3D printing to produce a complete set-up for a fraction of the cost of those night-vision goggles of old.

At its heart is a little NTSC/PAL LCD display in a 3D printed bracket. These used to be a small display of choice, but we see them rarely now because standalone displays and the microcontrollers to drive them have become so much more useful. Driving the display is a video camera with its IR filter removed, and providing illumination is an IR flashlight. In effect it’s a classic analogue CCTV system in miniature, but the most important thing is that it works.

We might have expected a Raspberry Pi Zero and NoIR camera, but it’s difficult to argue with a functioning night vision system. If you want to look at a project with an image intensifier tube though, we’ve covered one of those in the past.