Sit Pretty On Would-Be Garbage With An Upcycled Chair

May 12, 2021 by 21 Comments

What’s the coolest thing about doing upholstery work? Aside from the fact that you end up with a new thing to sit on, sometimes the work only involves clever stapling, and no sewing is necessary. Such is the case with [wyldestyle]’s upcycled jeans chair, which started as a bare-wood swivel number from the dump. In fact, this project is almost completely made from recycled materials, except of course for those staples that hold it all together. And really, that heavy-duty stapler is likely the fanciest tool you’d need to make your own.

[wyldestyle] didn’t have any furniture foam, and we think that stuff is too expensive, anyway. So the padding treatment begins with a piece of thick Styrofoam that covers the seat screws and bolts. This is glued in place and trimmed down to match the contours of the chair’s seat and back.

Here’s where things gets tricky: the next step is wrapping over the stiff foam board with a few layers of that foam sheeting stuff that’s often used as packing material. This sheeting needs to be taut, but pull it too tight, and it will rip.

To add some loft to the chair, [wyldestyle] stretched and stapled the stuffing from an old pillow that was headed for the garbage. The final step is strategically scissoring jean scraps to fit, then stretching and stapling those to cover all the layers underneath. We like the way this chair looks, and would probably try to place pockets somewhere useful, like the back of the chair.

It’s a shame that so much denim goes to waste all over the world. There’s often a lot of life left in most of the fabric, which can be repurposed into all kinds of things, including eyeglasses frames using a wicked set of jigs.

Sinclair BASIC For Today

May 10, 2021 by 29 Comments

If you are of a certain age, your first exposure to computer programming was probably BASIC. For a few years, there were few cheaper ways to program in BASIC than the Sinclair ZX series of computers. If you long for those days, you might find the 1980-something variant of BASIC a little limiting. Or you could use SpecBasic from [Paul Dunn].

SpecBasic is apparently reasonably compatible with the Spectrum, but lets you use your better hardware. For example, instead of a 256×192 8-color screen, SpecBas accommodates larger screens and up to 256 colors. However, that does lead to certain incompatibilities that you can read about in the project’s README file.

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Apple AirTag Spills Its Secrets

May 10, 2021 by 17 Comments

The Apple AirTag is a $29 Bluetooth beacon that sticks onto your stuff and helps you locate it when lost. It’s more than just a beeper though, the idea is that it can be silently spotted by any iDevice — almost like a crowd-sourced mesh network — and its owner alerted of its position wherever they are in the world.

There are so many questions about its privacy implications despite Apple’s reassurances, so naturally it has been of great interest to those who research such things. First among those working on it to gain control of its nRF52832 microcontroller is [Stacksmashing], who used a glitching technique whereby the chip’s internal power supply is interrupted with precise timing, to bypass the internally enabled protection of its debug port. The firmware has been dumped, and of course a tag has been repurposed for the far more worthwhile application of Rickrolling Bluetooth snoopers.

The idea of a global network of every iDevice helping reunite owners with their lost possessions is on the face of it a very interesting one, and Apple are at great pains on the AirTag product page to reassure customers about the system’s security. On one hand this work opens up the AirTag as a slightly expensive way to get an nRF microcontroller for other applications, but the real value will come as the firmware is analysed to see how at the tag itself works.

[Stacksmashing] has appeared on these pages many times before, often in the context of Nintendo hardware. Just one piece of work is the guide to opening up a Nintendo Game and Watch.

Air-Assist Analysis Reveals Most Effective — And Quietest — Methods

May 9, 2021 by 19 Comments

If there’s one thing that continues to impress us about the Hackaday community as the years roll by, it’s the willingness to share what we’ve learned with each other. Not every discovery will be news to everyone, and everything won’t be helpful or even interesting to everyone, but the mere act of sharing on the off chance that it’ll help someone else is really what sets the hardware hacking world apart.

Case in point: this in-depth analysis of laser cutter air-assist methods. Undertaken by [David Tucker], this project reads more like a lab writeup than a build log, because well, that’s pretty much what it is. For those not into laser cutters, an air assist is just a steady flow of air to blow smoke and cutting residue away from the beam path and optics of a laser cutter. It’s simple, but critical; without it, smoke can obscure and reflect the laser beam, foul lenses and mirrors, and severely degrade cut quality.

To see what air-assist methods work best, [David] looked at four different air pumps and compressors, along with a simple fan. Each of these methods was compared to a control of cuts made without air assist. The test was simple: a series of parallel lines cut into particle board with the beam focused on the surface at 80% power, with the cut speed slowly decreasing. It turned out that any air-assist was better than nothing, with the conspicuous exception of using just a fan, which made things worse. Helpfully, [David] included measurements of the noise levels of the compressors he tested, and found there’s no advantage to using an ear-splitting shop compressor over a quieter aquarium air pump. Plus, the aquarium pumps are cheap — always a bonus.

Not sure how to get up to speed with lasers? Laser Cutting 101 might be a great place to start.

MIT’s Hair-Brushing Robot Untangles Difficult Robotics Problem

May 8, 2021 by 12 Comments

Whether you care to admit it or not, hair is important to self-image, and not being able to deal with it yourself feels like a real loss of independence. To help people with limited mobility, researchers at MIT CSAIL have created a hair-brushing robot that combines a camera with force feedback and closed-loop control to adjust to any hair type from straight to curly on the fly. They achieved this by examining hair as double helices of soft fibers and developed a mathematical model to untangle them much like a human would — by working from the bottom up.

It may look like a hairbrush strapped to a robot arm, but there’s more to it than that. Before it ever starts brushing, the robot’s camera takes a picture that gets cropped down to a rectangle of pure hair data. This image is converted to grayscale, and then the program analyzes the x/y image gradients. The straighter the hair, the more edges it has in the x-direction, whereas curly hair is more evenly distributed. Finally, the program computes the ratio of straightness to curliness, and uses this number to set the pain threshold.

The brush is equipped with sensors that measure the forces being exerted on the hair and scalp as it’s being brushed, and compares this input to a baseline established by a human who used it to brush their own hair. We think it would be awesome if the robot could grasp the section of hair first so the person can’t feel the pull against their scalp, and start by brushing out the ends before brushing from the scalp down, but we admit that would be asking a lot. Maybe they could get it to respond to exclamations like ‘ow’ and ‘ouch’. Human trials are still in the works. For now, watch it gently brush out various wigs after the break.

Even though we have wavy hair that tangles quite easily, we would probably let this robot brush our hair. But this haircut robot? We’re not that brave.

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SpaceX Drops The Ball On Catching Fairings

May 6, 2021 by 91 Comments

You don’t have to look very hard to find another rousing success by SpaceX. It’s a company defined by big and bold moves, and when something goes right, they make sure you know about it. From launching a Tesla into deep space to the captivating test flights of their next-generation Starship spacecraft, the private company has turned high-stakes aerospace research and development into a public event. A cult of personality has developed around SpaceX’s outlandish CEO Elon Musk, and so long as he’s at the helm, we can expect bigger and brighter spectacles as he directs the company towards its ultimate goal of putting humans on Mars.

Of course, things don’t always go right for SpaceX. While setbacks are inevitable in aerospace, the company has had a few particularly embarrassing failures that could be directly attributed to their rapid development pace or even operational inexperience. A perfect example is the loss of the Israeli AMOS-6 satellite during a static fire of the Falcon 9’s engines on the launch pad in 2016, as industry experts questioned why the spacecraft had even been mounted to the rocket before it had passed its pre-flight checks. Since that costly mistake, the company has waited until all engine tests have been completed before attaching the customer’s payload.

SpaceX’s concept art for propulsive landing

But sometimes the failure isn’t so much a technical problem as an inability for the company to achieve their own lofty goals. Occasionally one of Musk’s grand ideas ends up being too complex, dangerous, or expensive to put into practice. For instance, despite spending several years and untold amounts of money perfecting the technology involved, propulsive landings for the Crew Dragon were nixed before the idea could ever fully be tested. NASA was reportedly uncomfortable with what they saw as an unnecessary risk compared to the more traditional ocean splashdown under parachutes; it would have been an impressive sight to be sure, but it didn’t offer a substantive benefit over the simpler approach.

A similar fate recently befell SpaceX’s twin fairing recovery ships Ms. Tree and Ms. Chief, which were quietly retired in April. These vessels were designed to catch the Falcon’s school bus sized payload fairings as they drifted down back to Earth using massive nets suspended over their decks, but in the end, the process turned out to be more difficult than expected. More importantly, it apparently wasn’t even necessary in the first place.

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