flexure

10 Articles

Squid-Con Brings Joy To All

August 24, 2023 by 2 Comments

While we’re always happy to see accessibility aids come into fruition, most of them focus on daily tasks, not that there’s anything wrong with that. But what about having some fun? That’s the idea behind [Akaki Kuumeri]’s accessibly-awesome Joy-Con controller, the Squid-Con, which provides access to every button with just one hand. It even has tripod and AMPS mounts.

The joysticks themselves are controlled with the thumb and pinky, although some of [Akaki]’s beta testers changed it up a bit. That’s okay, because it’s designed to be comfortable in a variety of positions for either hand. As for the ABXY buttons, those are actuated using 3D-printed arms that connect to a central piece which [Akaki] calls the turbine.

But perhaps the coolest part of this project is the flexures that actuate the shoulder buttons (L, R, zL, and zR) on the controllers. It’s a series of four arms that are actuated by bringing the fingers back toward the palm. If all of this sounds confusing, just check out the video after the break.

We love flexures around here, and we’ve seen them in everything from cat feeding calendars to 6-DOF positioners to completely new kinds of joysticks.

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Physical Neural Network Can Be Trained Like A Digital One

July 20, 2023 by 11 Comments

Here’s an unusual concept: a computer-guided mechanical neural network (video, embedded below.) Why would one want a mechanical neural network? It’s essentially a tool to explore what it would take to make physical materials work in nonstandard ways. The main part is a lattice of interlinked mechanical components. When one applies a certain force in a certain direction on one end, it causes the lattice to deform in a non-intuitive way on the other end.

To make this happen, individual mechanical elements  in the lattice need to have their compliance carefully tuned under the guidance of a computer system. The mechanisms shown can be adjusted on demand while force is applied and cameras monitor the results.

This feedback loop allows researchers to use the same techniques for training neural networks that are used in machine learning applications. Ultimately, a lattice can be configured in such a way that when side A is pressed like this, side B moves like that.

We’ve seen compliant structures that move in unexpected ways before, and they are always fascinating. One example is this 3D-printed door latch that translates a twisting motion into a linear one. Research into physical neural networks seems like it might open the door to more complex systems, or provide insights into metamaterial design.

You can watch the video below just under the page break, or if you prefer, skip the intro and jump straight into How It Works at [2:32].

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This Block Of Rubber Can Count To Ten

July 6, 2023 by 19 Comments

Complex behaviors can arise from simple mechanics, and that’s demonstrated by a block of rubber that acts as a counter.

The block contains beams, and by controlling how the block is compressed, the vertical beams shift in a stable and consistent way, acting as a mechanical counter. It’s a straightforward implementation of the work of two physicists from the Netherlands: [Martin van Hecke] and [Lennard Kwakernaak].

This device brings flexures to mind, which are also examples of obtaining complex and useful behavior from seemingly simple objects. We’ve seen flexures used as latches and counters, and we’ve seen 3D printed flexures as a kind of linear actuator.

You can check out the research paper for more details on the rubber beam counter. [Kwakernaak] aims to create a much more complex structure with elements that interact across a plane instead of in a single direction. Such a device would, in effect, be a simple computer.

Watch the beam counter in action in the short video embedded below. See how the elements of the green rubber block move while constrained by an outer frame that helps control the force that is applied. The thin beams flip from left to right, one at a time with each press.

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A man sits in front of a wooden table. There is a black box with a number of knobs hand-labeled on blue painter's tape. A white breadboard with a number of wires protruding from it is visible on the box's left side. An oscilliscope is behind the black box and has a yellow waveform displaying on its screen.

A More Expressive Synth Via Flexure

February 28, 2023 by 13 Comments

Synthesizers can make some great music, but sometimes they feel a bit robotic in comparison to their analog counterparts. [Sound Werkshop] built a “minimum viable” expressive synth to overcome this challenge. (YouTube)

Dubbed “The Wiggler,” [Sound Werkshop]’s expressive synth centers on the idea of using a flexure as a means to control vibrato and volume. Side-to-side and vertical movement of the flexure is detected with a pair of linear hall effect sensors that feed into the Daisy Seed microcontroller to modify the patch.

The build itself is a large 3D printed base with room for the flexure and a couple of breadboards for prototyping the circuits. The keys are capacitive touch pads, and everything is currently held in place with hot glue. [Sound Werkshop] goes into detail in the video (below the break) on what the various knobs and switches do with an emphasis on how it was designed for ease of use.

If you want to learn more about flexures, be sure to checkout this Open Source Flexure Construction Kit.

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An Open Source Modular Flexure Construction Set

November 22, 2022 by 14 Comments

Flexures are one of those innocent-looking mechanisms that one finds inside practically any kind of consumer device. Providing constrained movements with small displacements, complete with controlled tension, they can be rather tricky to design. GrabCAD designer [Vyacheslav Popov] hails from Ukraine, and due to the current situation there, plans to sell a collection of flexure building blocks became difficult. In the end, [Vyacheslav] decided to generously release his work open source, for all to enjoy. This collection is quite extensive, looking like it could solve a huge variety of flexure design problems. (Links to the first three sets: Set00, Set01, Set02 but check the author’s collection page for many others)

It’s not just those super-cheap mechanisms in throw-away gadgets that leverage flexures, it’s much more. The Mars rovers use flexure-based suspension, scientific instruments (interferometers and the like) make use of them for small motions where specific axis constraints are needed, and finally, MEMS accelerometers and gyroscopes are based entirely upon them. We’re not even going to try to name examples of flexures in the natural world. They’re everywhere. And, now we’ve got some more design examples to use, so why not flex your flexure muscles and send one to the 3D printer and have a play?

We see flexures here quite a bit, like this nice demonstration of achievable accuracy. Flexures can make some delicious mechanisms, and neat 3D printable input devices.

Thanks to [Addison] for the tip!

Filament Cutter Uses Unusual (But Effective) 3D-Printed Spring Design

September 23, 2022 by 12 Comments

When one needs a spring, a 3D-printed version is maybe not one’s first choice. It might even be fair to say that printed springs are something one ends up making, rather than something one sets out to use. That might change once you try the spring design in [the_ress]’s 3D-printed filament cutter with printed springs.

The filament cutter works like this: filament is inserted into the device through one of the pairs of holes at the bottom. To cut the filment, one presses down on the plunger. This pushes a blade down to neatly cut the filament at an angle. The cutter is the device’s only non-printed part; a single segment from an 18 mm utility knife blade.

The springs are of particular interest, and don’t look quite like a typical spring. They take their design from this compliant linear motion mechanism documented on reprap.org, and resemble little parallel 4-bar linkages. These springs have limited travel, but are definitely springy enough for the job they need to do, and that’s the important part.

Want a more traditional coiled spring? Annealing filament wound around a mandrel can yield useful results, and don’t forget the fantastic mechanisms known as flexures; they have clear similarities to the springs [the_ress] used. You can see her design in action in the short video, embedded below.

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3D Printed Flexure Shows Precision In Action

June 3, 2022 by 17 Comments

Here’s an older but fantastic video that is as edifying as it is short. [Topias Korpi] demonstrates a 3D printed flexure with a dial indicator on one end, and an M3 screw on the other. As the screw is turned, the dial indicator moves steadily with roughly a 15:1 reduction between the movement of the screw and the indicator. Stable deflections of 0.01 mm are easily dialed in, and it’s neat seeing it work while the flexure itself shows no perceptible movement. A demonstration is embedded below the page break and is less than a minute long, so give it a watch and maybe get some ideas.

Flexures are fantastic designs capable of a wide variety of physical functions, and just as [Topias]’s demonstration shows, they can be a natural complement to 3D printing. In fact, flexures are an important part of the design and function of JWST’s mirror actuators, which are responsible for making astonishingly small adjustments to each of the space telescope’s 18 mirror sections.

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