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Hackaday Links: April 24, 2022

April 24, 2022 by 11 Comments

Wait, what? Is it possible that a tech company just killed off a product with a huge installed base of hardware and a community of dedicated users, and it wasn’t Google? Apparently not, if the stories of the sudden demise of Insteon are to be believed. The cloud-based home automation concern seems to have just disappeared — users report the service went offline at the end of last week, and hasn’t been back since. What’s more, the company’s executives removed Insteon from their LinkedIn profiles, and the CEO himself went so far as to remove his entire page from LinkedIn. The reasons behind the sudden disappearance remained a mystery until today, when The Register reported that Smartlabs, Inc., the parent company of Insteon, had become financially insolvent after an expected sale of the company failed in March. The fact that the company apparently knew this was going to happen weeks ago and never bothered to give the community a heads up before pulling the switches has led to a lot of hard feelings among the estimated 100,000 Insteonhub users.

Then again, with a comet the size of Rhode Island heading our way, a bunch of bricked smart bulbs might just be a moot point. The comet, known as C/2014 UN271, has a nucleus that is far larger than any previously discovered comet, which makes it a bit of an oddball and an exciting object to study. For those not familiar with the United States, Rhode Island is said to be a state wedged between Connecticut and Massachusetts, but even having lived in both those states, we couldn’t vouch for that. For scale, it’s about 80 miles (128 km) across, or a little bit bigger than Luxembourg, which we’re pretty sure is mythical, too. The comet is a couple of billion miles away at this point; it may never get closer than a billion miles from the Sun, and that in 2031. But given the way things have been going these last few years, we’re not banking on anything.

From the “Answering the Important Questions” file, news this week of the Massachusetts Institute of Technology’s breakthrough development of the “Oreometer,” a device to characterize the physical properties of Oreo cookies. The 3D printed device is capable of clamping onto the wafer parts of the popular sandwich cookie while applying axial torque. The yield strength of the tasty goop gluing the two wafers together can be analyzed, with particular emphasis on elucidating why it always seems to stay primarily on one wafer. Thoughtfully, the MIT folks made the Oreometer models available to one and all, so you can print one up and start your own line of cookie-related research. As a starting point, maybe take a look at the shear strength of the different flavors of Oreo, which might answer why the world needs Carrot Cake Oreos.

And finally, since we mentioned the word “skiving” last week in this space, it seems like the all-knowing algorithm has taken it upon itself to throw this fascinating look at bookbinding into our feed. We’re not complaining, mind you; the look inside Dublin’s J.E. Newman and Sons bookbinding shop, circa 1981, was worth every second of the 23-minute video. Absolutely everything was done by hand back then, and we’d imagine that very little has changed in the shop over the ensuing decades. The detail work is incredible, especially considering that very few jigs or fixtures are used to ensure that everything lines up. By the way, “skiving” in this case refers to the process of thinning out leather using a razor-sharp knife held on a bias to the material. It’s similar to the just-as-fascinating process used to make heat sinks that we happened upon last week.

DIY Prony Dyno Properly Displays Power Production

March 25, 2022 by 13 Comments

When hackers in the US think of a retailer called Harbor Freight, we usually think of cheap tools, workable but terrible DVM’s, zip ties, and tarps. [Jimbo] over at [Robot Cantina] looked at the 212cc “Predator” engine that they sell and thought “I bet I could power my Honda Insight with that.” And he did, successfully! How much power did the heavily modified engine make? In the video below the break, [Jimbo] takes us through the process of measuring its output using a home built dyno.

The dyno that [Jimbo] has built is a Prony Dyno, and it’s among the oldest and simplest designs available. A torque arm is extended from a disk brake caliper and connects to a force gauge. The engine is ran up to its highest speed, and then he brake is applied to the crankshaft until the engine almost stalls. A tachometer keep track of the RPM, and the force gauge measures the force on the torque arm. Torque is multiplied by RPM and the result is divided by a constant of 5252, and voilà: Horsepower. A computer plots the results across the entire range, and the dyno test is complete.

That only tells part of the story, and the real hack comes when you realize that the dyno stand, the force gauge setup and pretty much everything that can be built at home has been built at home. You’ll also enjoy seeing the results of some driving tests between the 212cc engine and its bigger 420cc brother, how even minor changes to the engine affect the horsepower and torque curves, and how that affects the Honda that he calls his “Street legal go cart.”

Speaking of unusual power plants, how about plant some hobby sized jet turbines on the back of your Tesla for fun?

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Internal Combustion Torque Monster Has Great Impact

March 3, 2022 by 26 Comments

Once the domain of automotive repair shops and serious hobbyists with air compressors, the impact driver so famously used to remove and install wheel lug nuts and other Big Fasteners with just a squeeze of the trigger is more accessible than ever. Thanks to Lithium Ion batteries and powerful and compact brushless motors, you can now buy a reasonably powerful and torquey impact driver for a relatively low price- no air compressor needed! But what if you relish the thought of a noisy, unwieldy and unnecessarily loud torque monster? Then the video below the break by [Torque Test Channel] is just what you need!

Now, this is Hackaday, so we don’t have to go into detail about why a person might want to rip out the electric motor and adapt a 60cc 2 stroke engine in its place. Of course that’s the obvious choice. But [Torque Test Channel] isn’t just mucking about for the fun of it. No, they’re having their fun, experimenting with internal combustion engines in odd places before they are banned by 2024 in California. Now, we’re not sure if the ban includes these exact types of engines- but who needs details when you have an impact driver that can change semi tires like a NASCAR pit crew.

Looking like an overpowered weapon from a first person shoot’em up game, [Torque Test Channel]’s modified Milwaukee tests well after some modifications. Be sure to watch the video to see how it performs against an electric tool that’s even larger than itself. There are graphs, charts, and an explanation of what can be done to make even more power in the future. We’re looking forward to it!

What’s that you say? You don’t have a two stroke engine sitting around waiting to be swapped into ridiculous gadgets? Look no further than your local fridge compressor and be ready to burn some hours getting it running.

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Harmonic Drive Uses Compliant Mechanism To Slim Down

April 7, 2021 by 15 Comments

[Levi Janssen] has a secret: he doesn’t like harmonic drives. But rather than abandon the torque-amplifying transmission completely, he decided to see about improving them using 3D-printed compliant mechanisms.

For the uninitiated, harmonic drives, also known as strain-wave gears, are a compact, high-torque gearbox that has become popular with “robotic dog” makers and other roboticists. The idea is to have a rigid, internally-toothed outer ring nested around an externally-toothed, flexible cup. A wave generator rotates within the inside cup, stretching it so that it meshes with the outer ring. The two gears differ by only a couple of teeth, meaning that very high gear ratios can be achieved, which makes them great for the joints of robot legs.

[Levi]’s problem with the harmonic drive is that due to the depth of the flexible spline cup, compactness is not among its virtues. His idea is to couple the flex spline to the output of the drive through a flat spring, one that allows flexion as the wave generator rotates but transmits torque efficiently. The entire prototype is 3D-printed, except for the wave generator bearings and stepper motor, and put to the test.

As the video below shows after the excellent introduction to harmonic drives, the concept works, but it’s not without its limitations. Even lightly loaded, the drive made some unpleasant crunching sounds as the PLA springs gave out. We could easily see that being replaced with, say, a steel spring, either machined or cut on a water-jet machine. That might solve the most obvious problem and make [Levi]’s dream of a compact harmonic drive a reality. Of course, we have seen pretty compact strain-wave gears before.

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This Custom Dynamometer Is A Stirling Example Of Homebrewing

April 6, 2021 by 25 Comments

[Leo Fernekes] has fallen down the Stirling engine rabbit hole. We mustn’t judge — things like this happen in the best of families, after all. And when they do happen to someone like [Leo], things can get interesting mighty quickly.

His current video, linked below, actually has precious little to do with his newfound Stirling engine habit per se. But when you build a Stirling engine, and you’re of a quantitative bent, having some way to measure its power output would be handy. That’s a job for a dynamometer, which [Leo] sets out to build in grand fashion. Dynos need to measure the torque and rotational speed of an engine while varying the load on it, and this one does it with style.

[Leo]’s torque transducer is completely DIY, consisting of hand-wound coils on the ends of a long lever arm that’s attached to the output shaft of the engine under test by a magnetic coupling. The coils are free to move within a strong magnetic field, with a PID loop controlling the current in the coils. Feedback on the arm’s position is provided by an optical sensor, also DIY, making the current necessary to keep the arm stationary proportional to the input torque. The video goes into great detail and has a lot of design and build tips.

We just love the whole vibe of this build. There may have been simpler or quicker ways to go about it, but [Leo] got this done with what he had on hand for a fraction of what buying in off-the-shelf parts would have cost. And the whole thing was a great learning experience, both for him and for us. It sort of reminds us of a dyno that [Jeremy Fielding] built a while back, albeit on a much different scale.

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Simple Demo Shows The Potential Of Magnetic Gears

April 13, 2020 by 27 Comments

We’ve probably all used gears in our projects at one time or another, and even if we’re not familiar with the engineering details, the principles of transmitting torque through meshed teeth are pretty easy to understand. Magnetic gears, though, are a little less intuitive, which is why we appreciated stumbling upon this magnetic gear drivetrain demonstration project.

[William Fraser]’s demo may be simple, but it’s a great introduction to magnetic gearing. The stator is a block of wood with twelve bolts to act as pole pieces, closely spaced in a circle around a shaft. Both ends of the shaft have rotors, one with eleven pairs of neodymium magnets arranged in a circle with alternating polarity, and a pinion on the other side of the stator with a single pair of magnets. When the pinion is spun, the magnetic flux across the pole pieces forces the rotor to revolve in the opposite direction at a 12:1 ratio.

Watching the video below, it would be easy to assume such an arrangement would only work for low torque applications, but [William] demonstrated that the system could take a significant load before clutching out. That could even be a feature for some applications. We’ve got an “Ask Hackaday” article on magnetic gears if you want to dive a little deeper and see what these interesting mechanisms are good for.

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Can Lego Break Steel?

March 17, 2020 by 14 Comments

Betteridge’s Law of Headlines holds that any headline ending in a question mark can be answered with a resounding “No”. But as the video below shows, a Lego machine that twists steel asunder is not only possible, it’s an object lesson in metal fatigue. Touché, [Betteridge].

In pitting plastic against metal, the [Brick Experiment Channel] relied on earlier work with a machine that was able to twist a stock plastic axle from the Technics line of parts like a limp noodle. The steel axle in the current work, an aftermarket part that’s apparently no longer available, would not prove such an easy target.

Even after beefing up the test stand with extra Technics struts placed to be loaded in tension, and with gears doubled up and reinforced with extra pins, the single motor was unable to overcome the strength of the axle. It took a second motor and a complicated gear train to begin to deform the axle, but the steel eventually proved too much for the plastic to withstand. Round Two was a bit of a cheat: the same rig with a fresh axle, but this time the motor rotation was constantly switched. The accumulated metal fatigue started as a small crack which grew until the axle was twisted in two.

The [Brick Experiment Channel] is a fun one to check out, and we’ve featured them before. Along with destructive projects like this one, they’ve also got fun builds like this Lego playing card launcher, a Technic drone, and a Lego submarine.

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