Hacked Car Axle Yields Custom 90° Gearbox

Need a sturdy angle gearbox to handle power transmission for your next big project? Why not harvest a rear axle from a car and make one yourself?

When you think about it, the axle of a rear-wheel drive vehicle is really just a couple of 90° gearboxes linked together internally, and a pretty sturdy assembly that’s readily available for free or on the cheap. [Donn DIY]’s need for a gearbox to run a mower lead him to a boneyard for the raw material. The video below shows some truly impressive work with that indispensable tool of hardware hackers, the angle grinder. Not only does he amputate one of the half axles with it, he actually creates almost perfect splines on the remaining shortened shaft. Such work is usually done on a milling machine with a dividing head and an end mill, but [DonnDIY]’s junkyard approach worked great. Just goes to show how much you can accomplish with what you’ve got when you have no choice.

We’re surprised to not see any of [DonnDIY]’s projects featured here before, as he seems to have quite a body of hacks built up. We hope to feature some more of his stuff soon, but in the meantime, you can always check out some of the perils and pitfalls of automotive differentials.

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Celebrating a Subscriber Milestone with a Copper YouTube Play Button

YouTube channels unboxing their latest “Play Button Award,” a replica of the famous logo in silver, gold, or faux-diamond depending on the popularity of the channel, are getting passé. But a metalworking channel that makes its own copper Play Button award to celebrate 25,000 subs is something worth watching.

[Chris DePrisco] is a bit of a jack-of-all-trades, working in various materials but with a strong focus on metalwork. He recently completed a beefy home-brew vertical milling center; we covered his attempt to leverage that platform by adding an extruder and turning it into a large bed 3D printer. For the Play Button build, [Chris] turned to the VMC to mill a mold from what appears to be a block of graphite; good luck cleaning that mess up. He melted copper scrap in a homemade electric furnace and poured it into the preheated mold — a solid tip for [The King of Random]’s next copper casting attempt. The rough blank was CNC machined and polished into the Play Button, and finally mounted behind glass neatly inked with paint pens in the versatile VMC. The final result is far nicer than any of the other Button awards, at least in our opinion.

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A Magic Light Bulb For All Your Bright Ideas

[Uri Shaked]’s lamentation over the breaking of his smart bulb was brief as it was inspiring — now he had a perfectly valid excuse to hack it into a magic light bulb.

The first step was disassembling the bulb and converting it to run on a tiny, 130mAh battery. Inside the bulb’s base, the power supply board, Bluetooth and radio circuits, as well as the LED board didn’t leave much room, but he was able to fit in 3.3V and 12V step-up voltage regulators for the LiPo battery.

[Shaked]’s self-imposed bonus round was to also wedge a charging circuit — which he co-opted from a previous project — into the bulb instead of disassembling it every time it needed more juice. Re-soldering the parts together: easy.  Fitting everything inside a minuscule puzzle-box: hard. Kapton tape proved eminently helpful in preventing shorts in the confined space.

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Paper Circuit Does Binary Math with Compressed Air

Most of us can do simple math in our heads, but some people just can’t seem to add two numbers between 0 and 3 without using paper, like [Aliaksei Zholner] does with his fluidic adder circuit built completely of paper.

Pneumatic AND gate

There’s some good detail in [Aliaksei]’s translated post on the “Only Paper” forum, a Russian site devoted to incredibly detailed models created entirely from paper. [Aliaksei] starts with the basic building blocks of logic circuits, the AND and OR gates. Outputs are determined by the position of double-headed pistons in chambers, with output states indicated by pistons that raise a flag when pressurized. The adder looks complicated, but it really is just a half-adder and full-adder piped together in exactly the same way it would be wired up with CMOS or TTL gates. The video below shows it in action.

If [Aliaksei]’s name seems familiar, it’s because we’ve featured his paper creations before, including this working organ and a tiny working single cylinder engine. We’re pleased with his foray into the digital world, and we’re looking forward to whatever is next.

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Big Slew Bearings Can Be 3D Printed

Consider the humble ball bearing. Ubiquitous, useful, and presently annoying teachers the world over in the form of fidget spinners. One thing ball bearings aren’t is easily 3D printed. It’s hard to print a good sphere, but that doesn’t mean you can’t print your own slew bearings for fun and profit.

As [Christoph Laimer] explains, slew bearings consist of a series of cylindrical rollers alternately arranged at 90° angles around an inner and outer race, and are therefore more approachable to 3D printing. Slew bearings often find application in large, slowly rotating applications like crane platforms or the bearings between a wind turbine nacelle and tower. In the video below, [Christoph] walks us through his parametric design in Fusion 360; for those of us not well-versed in the app, it looks a little like magic. Thankfully he has provided both the CAD files and a selection of STLs for different size bearings.

[Christoph] is no stranger to complex 3D-printable designs, like his recent brushless DC motor or an older clock build. The clock is cool, but the bearings and motors really get us — we’ll need such designs to get to self-replicating machines.

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Scanning Electron Microscope Adds to Already Impressive Garage Lab

When you’re a high schooler who built a semiconductor fab in your garage, what’s next on your agenda? Why, adding a scanning electron microscope to your lab, naturally. How silly of you to ask.

When last we stumbled across the goings on in the most interesting garage in New Jersey, [Sam Zeloof] was giving a tour of his DIY semiconductor fabrication lab and showing off some of the devices he’s made there, including diodes and MOSFETs. As impressive as those components are, it’s the equipment he’s accumulated that really takes our breath away. So adding an eBay SEM to the mix only seems a natural progression, and a good reason to use some of the high vacuum gear he has. The video below shows [Sam] giving a tour of the 1990s-vintage instrument and shows images of various copper-sputtered samples, including a tick, which is apparently the state bird of New Jersey.

SEM hacks are by no means common around here, but they’re not unheard of. [Ben Krasnow] has used his to image cutting tools and phonograph records in action, and there are a few homebrew SEMs kicking around too. But our hats are off to [Sam] for yet another acquisition and a great tutorial to boot.

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Being a Friend to Man’s Best Friend

When [Jason Dorie] tipped us off on this, he said, “This barely qualifies as a hack.” We disagree, as would any other dog lover who sees how it improved the life of his dog with a simple mood-altering doggie-bed carousel.

[Jason]’s hack lies not so much in the rotating dog bed – it’s just a plywood platform on a bearing powered by a couple of Arlo robot wheels. The hack is more in figuring out what the dog needs. You see, [Thurber] is an old dog, and like many best friends who live a long life, he started showing behavioral changes, including endlessly pacing out the same circular path to the point of exhaustion. Circling in old dogs is often a symptom of canine cognitive dysfunction, which is basically the dog version of Alzheimer’s. Reasoning that the spinning itself was soothing, [Jason] manually turned [Thurber]’s dog bed on the floor. [Thurber] calmed down immediately, so the bittersweetly named “Dementia-Go-Round” was built.

Sadly, [Thurber] was actually suffering from a brain tumor, but he still really enjoyed the spinning and it gave him some peace during his last few days. Looking for hacks to help with human dementia? We’ve had plenty of those before too.

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