Day: June 3, 2022

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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This Week In Security: Follina, Open Redirect RCE, And Annoyware

June 3, 2022 by 1 Comment

Depending on who you ask, there’s either 2 vulnerabilities at play in Follina, only one, or according to Microsoft a week ago, no security problem whatsoever. On the 27th of last month, a .docx file was uploaded to VirusTotal, and most of the tools there thought it was perfectly normal. That didn’t seem right to [@nao_sec], who raised the alarm on Twitter. It seems this suspicious file originated somewhere in Belarus, and it uses a series of tricks to run a malicious PowerShell script.
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A Rotocasting Machine Sized For The Home Shop

June 3, 2022 by 5 Comments

If you’ve ever wondered how large, hollow plastic structures like tanks and drums are formed, you’re in luck: [Andy] not only fills us in on the details of rotational casting and molding, but he also built this sweet little rotational casting machine to help him with his DIY projects.

Granted, [Andy]’s build won’t be making anything too large, like a car fuel tank or a kayak. Not only is it sized more for smallish parts, but those structures are generally made with the related process of rotational molding. Both processes use an enclosed multipart mold that’s partially filled with plastic resin, and then rotate the mold around two axes to distribute a thin layer of resin around the inside of the mold. The difference is that roto-molding uses a thermoplastic resin, whereas roto-casting uses resins like polyurethane and silicone that set at room temperature.

The machine looks simple, but only because he took great pains to optimize it. The videos below cover the build in detail — feel free to skip to the 11:38 mark of the second video if you just want to see it in action. Though you’ll be missing some juicy tidbits, like welding a perfect 90° joint in square tubing. There’s also the custom tool [Andy] built to splice the beaded chain he used to drive the spinning of the mold, which was pure genius.

Using the machine and a complex nine-piece mold, [Andy] was able to create remarkably detailed tires for RC cars from polyurethane resin. We’d love to see what else this rig is good for — almost as much as we want to see details on how the mold was made. We’ve seen other rotational casting machines before, but this one takes the cake for fit and finish.

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Recycled Speed Boat Beats The Barnacles Out Of Your Average Rebuild

June 3, 2022 by 33 Comments

There’s an old saying that says “Anything is possible with enough Time, Money, or Brains. Pick two.” For [Mr HỒ Thánh Chế], the choice was obvious: Time, and Brains. This is evident by the impressive DIY boat build shown in the video below the break.

[Mr HỒ] starts with an Isuzu marine diesel engine that was apparently found on the beach, covered in barnacles and keel worms (and who knows what else). A complete teardown reveals that the crankcase was miraculously spared the ravages of the sea, and somehow even the turbo survived. After a good cleaning and reassembly, the engine rumbles to life. What’s notable is that the entire engine project was done with only basic tools, save for a lathe. Even generally disposable parts such as the head gasket are re-used.

Moving onto the hull, half of an old damaged boat is used and a new top is built. Car seats out of a Toyota sit behind a steering column also from a car, while the deck is built from scratch out of square tubing, foam board, and fiberglass.

What we liked about the project isn’t so much the end result, it has some build quality issues and it looks like the steering is far too slow, but what project of our own hasn’t been knocked together for fun with some obvious flaws? In fact, that’s very often the epitome of the Hacker spirit- doing it quick, dirty, having fun, and iterating as we go. For that, our hat is off to [Mr HỒ].

If boat recycling puts the wind in your sails, check out this boat-turned-sauna project.

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