3D Printed Joystick Using Spherical Flexure Joint

May 25, 2021 by Danie Conradie 19 Comments

One of the many advancements brought about by 3D printing is the rapid development of compliant mechanisms and flexure joints. One such example is [jicerr]’s joystick, which uses a pair of spherical flexure joints recently developed by researchers from Delft University of Technology in the Netherlands, See the videos after the break.

Both flexure joint designs make use of tetrahedron-shaped elements, allowing an object to pivot around a fixed point in space like a ball-and-socket joint. One of the joints, named Tetra 2, is perfect for printing on a standard FDM printer, and the 3D files were uploaded to Thingiverse by [Jelle_Rommers], one of the researchers. [jicerr] took the design and created a base to mount an HMC5883 3-axis magnetometer a short distance from the focal point, which senses the rotation of a small magnet at the focal point. An Arduino takes the output from the magnetometer, does the necessary calculation, and interfaces to a PC as a joystick. Demonstrates this by using it to rotate and pan the design in Solidworks. One thing to keep in mind with this design is that it needs a fixed base to prevent it from moving around. It should also be possible to integrate the design directly into the housing of a controller.

Another amusing application is to turn it into a pen holder with a chicken head on the front, as demonstrated by [50Pro]. If you have any ideas for other applications, drop them in the comments.

Compliant mechanisms have a number of interesting applications, including harmonic drives, dial indicators and thrust vectoring mounts.

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A Close Look At USB Power

May 22, 2021 by Tom Nardi 29 Comments

It’s not a stretch to say that most devices these days have settled on USB as their power source of choice. While we imagine you’ll still be running into the occasional wall wart and barrel jack for the foreseeable future, at least we’re getting closer to a unified charging and power delivery technology. But are all USB chargers and cables created equal?

The answer, of course, is no. But the anecdotal information we all have about dud USB gear is just that, which is why [Igor Brkić] wanted to take a more scientific approach. Inspired by the lighting bolt icon the Raspberry Pi will flash on screen when the voltage drops too low, he set out to make a proper examination of various USB chargers and cables to see which ones aren’t carrying their weight.

In the first half of his investigation, [Igor] tests four fairly typical USB chargers with his TENMA 72-13200 electronic load. Two of them were name brand, and the other just cheap clones. He was surprised to find that all of the power supplies not only met their rated specifications, but in most cases, over-performed by a fair amount. For example the Lenovo branded charger that was rated for only 1 A was still putting out a solid 5 V at 1.7 A. Of course there’s no telling what would happen if you ran them that high for hours or days at a time, but it does speak to their short-term burst capability at least.

He then moved onto the USB cables, were things started to fall apart. The three generic cables saw significant voltage drops even at currents as low as 0.1 A, though the name brand cable with 20 AWG power wires did fare a bit better. But by .5 A they were all significantly below 5 V, and at 1 A, forget about it. Pulling anything more than that through these cables is a non-starter, and in general, you’ll need to put at least 5.2 V in if you want to actually run a USB device on the other side.

Admittedly this might not be groundbreaking research, but we appreciate [Igor] taking a scientific approach and tabulating all the information. If you’re still getting low voltage warnings on the Pi after swapping out your cheapo cables, then maybe the problem is actually elsewhere.

Transparent Hard Drive Gives Peek At The Platters

May 19, 2021 by Tom Nardi 29 Comments

Solid-state drives (SSDs) are all the rage these days, and for good reason. But that doesn’t mean the era of the spinning disk is over, as traditional mechanical hard drives still offer a compelling value for mass storage applications where access times aren’t as critical. But the components inside these “slow” mechanical drives are still moving at incredible speeds, which [The Developer Guy] has nicely illustrated with his transparent hard drive.

Now unfortunately the technology to produce a fully transparent hard drive doesn’t exist, but laser cutting a new top plate out of acrylic is certainly within the means of the average hacker. The process is pretty straightforward: cut out a piece of clear plastic in the same shape and size as the drive’s original lid, put the appropriate mounting holes in it, and find some longer screws to accommodate the increased thickness.

Because this is just for a demonstration, [The Developer Guy] doesn’t need to worry too much about dust or debris getting on the platters; but we should note that performing this kind of modification on a drive you intend on actually using would be a bad idea unless you’ve got a cleanroom to work in.

In the videos below [The Developer Guy] records the drive while it’s in use, and at one point puts a microscope on top of the plastic to get a close-up view of the read/write head twitching back and forth. We particularly liked the time-lapse of the drive being formatted, as you can see the arm smoothly moving towards the center of the drive. Unfortunately the movement of the platters themselves is very difficult to perceive given their remarkably uniform surface, but make no mistake, they’re spinning at several thousand RPM.

Have an old mechanical drive of your own that you’re not sure what to do with? We’ve seen them turned into POV clocks, impromptu rotary encoders, and even surprisingly powerful blower fans.

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Improved Graphics-to-Drawing Tablet Conversion

May 7, 2021 by Chris Lott 7 Comments

[Akaki Kuumeri] had an old Wacom Intuos digitizing graphics tablet collecting dust, and figured out how to non-destructively transform it into a drawing tablet. He was inspired by an old Hackaday post of a similar hack, but it required literally hacking a big hole into your Wacom tablet. Not wanting to permanently ruin the Wacom tablet, [Akaki] instead designed a 3D printed frame which he holds in place with a pair of straps. The design files are available on Thingiverse. He names the project, incorrectly as he later points out, WacomOLED (it rhymes with guacamole, we think).

As for the screen, he buys an old third-generation iPad and removes its Retina display panel and the foil backing, which would otherwise block the stylus’s connection to the tablet. Toss in an HDMI driver board to connect the display to your computer, and presto — you have made your own a drawing tablet. Even if you don’t need a drawing tablet, [Akaki]’s hack is still interesting, if only to remind us that we can put custom HDMI displays into any project for $65 using this technique.

In the end, [Akaki] notes that unless you already have a non-graphical digitizing tablet laying around, it’s probably cheaper to just buy a iPad. This is not [Akaki]’s first go at user input devices — we wrote about his Smash Brothers game controller and flight controller yoke project last year.

Do any of you use a graphics tablet in your day to day workflow? Let us know in the comments below.

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TypeMatrix EZ-Reach 2030 Is Better Than Your Laptop Keyboard

May 4, 2021 by Kristina Panos 38 Comments

Maybe you’re not ready to take the leap into a full-on ergonomic split keyboard. That’s okay, that’s cool, that’s understandable. They’re weird! Especially ones like my Kinesis Advantage with the key bowls and such. But maybe your poor pinkies are starting to get tired and you’re ready to start using your thumbs for more than just the space bar. Or you want to be able to type ‘c’ properly, with your middle finger.

In that case, the TypeMatrix could be the keyboard for you. Or maybe for travel you, because it’s designed as a quasi-ergonomic, orthonormal layout travel keyboard to pair with your laptop, and as such it sits directly over a laptop keyboard without blocking the track pad. (How do people use those things, anyway?)

Of course, you could use this as a desktop keyboard as well, although it’s unfortunate that Control and Shift are stuck on the pinkies. More about that later.

First Impressions

When I saw this keyboard on eBay, I was attracted by two things: the layout, and the dedicated Dvorak light. (And, let’s be honest — the price was right.) I’ve always found myself generally turned off by chocolate bar-style ortholinear keebs because they’re so incredibly cramped, but this one seemed a more acceptable because of the slight split.

The first thing I noticed was the fantastic number pad integration. The different colored keycaps are a nice touch, because the gray makes the number pad stand out, and the red Delete is easy to find since Num Lock is squatting in the upper right corner. Why does Delete always feel like an afterthought on compact keebs? I also like the location of the arrows, and it makes me think of the AlphaSmart NEO layout. Unfortunately, it comes at the cost of burying the right hand Enter down in no-man’s land where you can’t exactly hit it blindly with great accuracy right away. If only you could swap Shift and Enter without messing up the number pad!

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Where We’re Going, We Don’t Need Keycaps

April 26, 2021 by Kristina Panos 14 Comments

Just when we thought we’d seen the peak of ergonomic, split keyboards, along comes [Peter Lyons] with the Squeezebox — an adjustable, column-staggered, streamlined beauty with 21 keys per hand. Much like the Kinesis Advantage and the Dactyl, the user’s fingers are allowed to dangle comfortably and stay in their naturally curled position, moving as little as possible between keys, rows, and columns. But the Squeezebox goes a few steps farther to reduce finger travel.

For starters, each column of keys is adjustable on the fly in the Y-direction by loosening the screw and sliding it until it’s just right. The columns are also adjustable in the Z-direction, but for now, this requires reprinting a few parts. In case you didn’t notice, the grid is pretty tightly packed, and those low-profile Kailh choc switches are naked to the world, mostly because keycaps wouldn’t fit anyway.

At that angle, there’s no reaching required at all between the middle and bottom rows. The 100° corner that they form both invites and supports chording — that’s pressing multiple keys simultaneously to do some action. There’s no real need to reach for the top row, either, because [Peter] merely moves his finger upward in the Z-direction a little bit to hit those. The similarly-angled thumb clusters are chord-able as well, and their position relative to the mainland is adjustable thanks to a grid of holes that are meant for threaded inserts. Genius!

For the next version, [Peter] plans to bring the three sets of thumb cluster switches closer together, and arrange them like a tri-fold science fair display board. Be sure to check out the super cool but somewhat impossible-to-solder prototypes in the build log, and stay for more stuff in the huge build gallery. Typing demo is after the break.

Still too much travel for your taste? How about a 5-way for each finger?

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The Beat Goes On With This ESP32 Page Turner

April 16, 2021 by Tom Nardi 3 Comments

Looking for a hands-free way to page through sheet music on an iPad, [The_Larch] came up with this simple Bluetooth input device based on the ESP32. The microcontroller just needed to have two switches wired into the GPIO pins, in this case the same heavy-duty plungers you’d find on a guitar pedal, and a USB bulkhead pass-through to provide power. Thanks to the excellent ESP32-BLE-Keyboard library, it only took a few lines of code to fire off the appropriate key strokes when the left or right button was pressed.

While undeniably a simple project from an electronics standpoint, the wooden enclosure [The_Larch] built is an interesting change of pace from the 3D printed fare we normally see around these parts. It started life as strips of oak reclaimed from an old kitchen table, which were laminated together to make a solid block. A large spade bit was then used to bore into the block to make a void for the electronics, and a second flat piece of oak was fashioned into a front panel.

Creating Bluetooth input devices with the ESP32 is so incredibly straightforward that we’re honestly a little surprised we don’t see the trick used more often. Especially when you consider all of the custom made keyboards that have graced these pages over the last couple of years. The tools are available for anyone who wants them, so you have to wonder if hackers just aren’t fond of using Bluetooth for something as important as a keyboard?