A man welds on a chassis

Electric Wheelchair Dump Truck Hack Really Hauls

Have you ever looked at a derelict electric wheelchair and thought “I bet I could make something great with that!” Of course you have- this is Hackaday, after all! And so did [Made in Poland], who managed to get a hold of a broken down electric wheelchair and put the full utility of his well equipped metalworking shop to work. The results? Lets just say it hauls.

What we really enjoyed about the build was that there wasn’t much that couldn’t be done by an average garage hacker with a drill press, angle grinder, and a stick welder. While it’s definitely nicer to have a lathe and a high quality welding table, plasma cutter, and everything in between, nothing that [Made in Poland] did in the video is such high precision that it would require those extensive tools. There may be some parts that would be a lot more difficult, or lower precision, but still functional.

Another aspect of the build is of course the control circuitry and user interface. Keeping the skid steer and castor approach meant that each motor would need to be controllable independently. To achieve this, [Made in Poland] put together a purely electromechanical drive controlled with momentary rocker switches and automotive relays to form a simple H-Bridge for each motor.

Of course you just have to watch until the end, because it really proves that a man will do anything to get out of hauling wood around! Old electric wheelchairs can also make a great base for big robots, as it turns out.

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An orange 3D printed four digit clock with rotating segments

Be Mesmerized By The Latest Time Twister

[Hans Andersson] has been creating marvelous twisting timepieces for over a decade, and we’re pleased to be able to share his latest mechanical clock contraption with our readers, the Time Twister 5.

In contrast to his previous LEGO-based clocks, version five of the Time Twister uses 3D printed segments, undoubtedly providing greater flexibility in terms of aesthetics and function. Each digit is a mechanical display, five layers vertical and three segments horizontal, with a total of three unique faces. Each layer of each display can be individually rotated by a servo, and this arrangement allows for displaying any number between zero and nine. The whole show is controlled by an Arduino MEGA and a DS3231 real-time clock.

Watching these upended prisms rotate into legible fifteen-segment digits is enjoyable enough already, but the mechanical sound created by this timepiece in motion is arguably even more satisfying. Check out the video below to see (and hear) for yourself. If you want to build one yourself, all the details are here.

We last covered [Hans Andersson] and his very first Time Twister clock way back in November 2011. Since then we’ve come across many impressive mechanical clocks, like this seven-segment work of art. We’re constantly impressed by the outstanding craftsmanship of these mechanical clocks, and it’s inspiring to see one of our OG horologists back in the saddle once more.

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The End Of The Electromechanical Era

When viewed from the far future, the early years of the 21st century will probably be seen as the end of a short era in human technological development. In the beginning of the 20th century, most everything was mechanical. There were certainly some electric devices, but consumer products like gramophone players and “movie” cameras were purely mechanical affairs. You cranked them up, and they ran on springs. Nowadays, almost every bit of consumer gear you buy will be entirely electronic. In between, there was a roughly 50 year period that I’m going to call the Electromechanical Era.

Jenny List’s teardown this week of an old Fuji film movie camera from 1972 captures the middle of this era perfectly. There’s a small PCB and an electric motor, but most of the heavy lifting in the controls was actually put on the shoulders of levers, bearings, and ridiculously clever mechanisms. The electrical and mechanical systems were loosely coupled, with the electrical controlled by the mechanical.

I’m willing to argue the specifics, but I’d preliminarily date the peak of the Electromechanical Era somewhere around 1990. Last year, I had to replace all of the rotted rubber drive belts in a Sony Walkman WM-D6C, a professional portable tape player and recorder produced from 1984-2002.

It’s not a simple tape recorder — the motors are electronically regulated to keep ridiculously constant speed for such a small device, and mine has Dolby B and C noise reduction circuitry packed inside along with some decent mic preamps. But still, when you press the fast-forward button, it physically shoves rubber-coated drive wheels out of the way, and sliding pieces of metal make it change modes of operation by making and breaking electrical contacts. Its precision lies as much in the mechanical assemblies and motors as in the electronics. It’s truly half electronic and half mechanical.

But that era is long over. The coming of the CD player signaled the end, although we didn’t see it at the time. Sure, there is a motor, but all the buttons are electronic, and all the “mechanism” is implemented almost entirely in silicon. The digital camera was possibly the last nail in the Electromechanical Era’s coffin: with no need to handle physical film, the last demand for anything mechanical evaporated. Open up a GoPro if you don’t know what I mean.

While I’ll be happy to never have to replace the drive rubber in a cassette recorder again, it’s with a little sadness that I think on the early iPods with their spinning metal hard drives, and how they gave way to the entirely silicon Zoom H5 recorder that I use now. It has a S/N ratio and quiet pre-amps, no wow or flutter, and a quality that would have been literally unbelievable when I bought the WM-D6C.

Still, if you find yourself in the thrift store, and you’ve never done so before, buy and take apart one of these marvels from a bygone era. A cassette recorder, even a cheap one, hides a wealth of electromechanical design.

DIY Mechanical Flux Dispenser Syringe Has Fine Control

[Perinski]’s design for a mechanical flux dispenser uses some common hardware and a few 3D printed parts to create a syringe with fine control over just how much of the thick stuff gets deposited. The design is slick, and there’s a full parts list to accompany the printed pieces. [Perinski] even has some useful tips on how to most effectively get flux into 5 mL syringes without making a mess, which is a welcome bit of advice.

There is also a separate companion design for a magnetic syringe cap. Not only does it have an O-ring to keep things sealed and clean, but the tip of the cap has a magnet embedded into it, so that it can be stowed somewhere safe while the dispenser is in use, and doesn’t clutter the workspace.

This is all a very interesting departure from the design of most syringe dispensers for goopy materials, which tend to depend on some kind of pneumatic action. Even so, we’ve also seen that it’s possible to have a compact DIY pneumatic dispenser that doesn’t require a bulky compressor.

If you can’t quite figure out how the ergonomics of [Perinski]’s design are intended to work one-handed, you’re not alone. One holds the syringe in their hand, and turns the large dial in small increments with a thumb to control extrusion. [Perinski] demonstrates it close-up around the 4:50 mark, but if you have a few minutes it is worth watching the entire video, embedded below.

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Mechanical 7-segment display

A One-Servo Mechanical Seven-Segment Display

The seven-segment display may be a bit prosaic after all these years, but that doesn’t mean there aren’t ways to spice it up. Coming up with a mechanical version of the typical photon-based display is a popular project, of which we’ve seen plenty of examples over the years. But this seven-segment display is quite a mechanical treat, and a unique way to flip through the digits.

With most mechanical displays, we’re used to seeing the state of each segment changed with some kind of actuator, like a solenoid or servo. [Shinsaku Hiura] decided on a sleeker design using a 3D-printed barrel carrying one cam for each segment. Each hinged segment is attached to an arm that acts as a follower, riding on its cam and flipping on or off in a set pattern. Which digit is displayed depends on the position of the barrel, which is controlled with a single servo and a pair of gears. It trades mechanical complexity for electrical simplicity and overall elegance, and as you can see from the video below, it’s pretty snappy.

We think the best part of this build is figuring out the shape of the cams. We wonder how they compare to the cam profiles in [Greg Zumwalt]’s mechanical display; it uses two separate discs with grooves, but the principle is pretty much the same.

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Prioritising Mechanical Multiplexer

When automating almost any moderately complex mechanical task, the actuators and drive electronics can get expensive quickly. Rather than using an actuator for every motion, mechanical multiplexing might be an option. [James Bruton] has considered using it in some of his many robotics projects, so he built a prioritizing mechanical multiplexer to demonstrate the concept.

The basic idea is to have a single actuator and dynamically switch between different outputs. For his demonstration, [James] used a motor mounted on a moving platform actuated by a lead screw that can engage a number of different output gears. Each output turns a dial, and the goal is to match the position of the dial to the position of a potentiometer. The “prioritizing” part comes in where a number of outputs need to be adjusted, and the system must choose which to do first. This quickly turns into a task scheduling problem, since there are a number of factors that can be used to determine the priority. See the video after the break to see different algorithms in action.

Instead of moving the actuator, all the outputs can connect to a single main shaft via clutches as required. Possible use cases for mechanical multiplexers include dispensing machines and production line automation. Apparently, the Armatron robotic arm sold by Radioshack in the ’80s used a similar system, controlling all its functions with a single motor.

[James] knows or two about robotics, having built many of them over the last few years. Just take a look at OpenDog and his Start Wars robots. Continue reading “Prioritising Mechanical Multiplexer”

Logitech Joystick Gets A Mechanical Sidekick

The mechanical keyboard rabbit hole is a deep one, and can swallow up as much money and time as you want to spend. If you’ve become spoiled on the touch and responsiveness of a Cherry MX or other mechanical switch, you might even start putting them on other user interfaces as well, such as this Logitech joystick that now sports a few very usable mechanical keys for the touch-conscious among us.

The Logitech Extreme 3D Pro that [ErkHal] and friend [HeKeKe] modified to accept the mechanical keys originally had a set of input buttons on the side, but these were unreliable and error-prone with a very long, inconsistent push. Soldering some mechanical switches directly on the existing board was a nice improvement, but the pair decided that they could do even better and rolled out an entire custom PCB to mount the keys more ergonomically. The switches are Kailh Choc V2 Browns and seem to have done a great job of improving the responsiveness of the joystick’s side buttons. If you want to spin up your own version, they’ve made the PCBs available on their GitHub page.

While [ErkHal] notes the switches aren’t the best and were only used since they were available, they certainly appear to work much better than what the joystick shipped with originally. In fact, we recently saw similar switches used to make a custom mechanical keyboard made for the PinePhone.