A Peek Inside Apple Durability Testing Labs

Apple is well-known for its secrecy, which is understandable given the high stakes in the high-end mobile phone industry. It’s interesting to get a glimpse inside its durability labs and see the equipment and processes it uses to support its IP68 ingress claims, determine drop ability, and perform accelerated wear and tear testing.

Check out these cool custom-built machines on display! They verify designs against a sliding scale of water ingress tests. At the bottom end is IPx4 for a light shower, but basically no pressure. Next up is IPx5, which covers low-pressure ambient-temperature spray jets from all angles – we really liked this machine! Finally, the top-end IPx7 and IPx8 are tested with a literal fire hose blast and a dip in a static pressure tank, simulating a significant depth of water. An Epson robot arm with a custom gripper is programmed to perform a spinning drop onto a hard surface in a repeatable manner. The drop surface is swapped out for each run – anything from a wooden sheet to a slab of asphalt can be tried. High-speed cameras record the motion in enough detail to resolve the vibrations of the titanium shell upon impact!

Accelerated wear and tear testing is carried out using a shake table, which can be adjusted to match the specific frequencies of a car engine or a subway train. Additionally, there’s an interview with the head of Apple’s hardware division discussing the tradeoffs between repairability and durability. He makes some good points that suggest if modern phones are more reliable and have fewer failures, then durability can be prioritized in the design, as long as the battery can still be replaced.

The repairability debate has been raging strong for many years now. Here’s our guide to the responsible use of new technology.

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Hackaday Prize 2023: An Anti-Tremor Handle, With No Electronics

Many of us will have seen the various active assistive devices which have appeared over the last few years to help people with a hand tremor. Probably the best known was a fork with a set of servos and an accelerometer, that kept the end of the utensil steady despite the owner’s hand movements. It’s a field which has the potential to help many people, but it’s undeniable that such technology comes with a cost.

What if the same effect could be achieved passively, without all those electronics? It’s something [Jacob] is investigating with his mechanical anti-tremor cup handle. It’s a university project completed as part of his studies so it’s very much a work-in-progress which if we’re being fair isn’t quite there yet, but we think the potential in this idea of bringing a useful assistive device at least bears further attention.

The write-up is available as a Norwegian PDF file so takes a little bit of Google Translate cut and pasting for an Anglophone. Sadly due to what must be report format requirements set by the university it’s long on procedure and shorter on engineering calculations than we’d like, but there’s an attempt to calculate the properties of the helical springs in each of the joints to match the likely forces. Our intuition is that the design as shown would require significantly more mass on the end of it than that of the mug and beverage alone to achieve some form of stability, but despite that as we said it’s an interesting enough idea that it deserves more thought.

Hand tremor assistive devices have appeared more than once on these pages before, here’s one for soldering that enlists the aid of a camera gimbal.

Feed Your Fasteners In Line, With A Bowl Feeder

If you spend much time around industrial processes, you may have seen a vibrating bowl feeder at work. It’s a clever but simple machine that takes an unruly pile of screws or nuts and bolts, and delivers them in a line the correct way up. They do this by shaking the pile of fasteners in a specific way — a spiral motion which encourages them to work to the edge of the pile and align themselves on a spiral track which leads to a dispenser. It’s a machine [Fraens] has made from 3D printed parts, and as he explains in the video below the break, there’s more to this than meets the eye.

The basic form of the machine has a weighted base and an upper bowl on three angled springs. Between the two is an electromagnet, which provides the force for the vibration. The electromagnet needed to be driven with a sine wave which he makes with an Arduino and delivers as PWM via an H-bridge, but the meat of this project comes in balancing the force and frequency with the stiffness of the springs. He shows us the enormous pile of test prints made before the final result was achieved, and it’s a testament to the amount of work put into this project. The final sequence of a variety of objects making the march round the spiral is pure theatre, but we can see his evident satisfaction in a job well done.

Oddly this isn’t the first bowl feeder we’ve seen, though it may be one of the most accomplished. We particularly like this tiny example for SMD parts.

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Hands-Free Compass Uses Haptic Feedback

If you’ve never experienced it before, getting turned around on a cloudy day in the woods or getting lost during an event like a snowstorm can be extremely disorienting and stressful — not to mention dangerous. In situations where travel goes outside the beaten path, it’s a good idea to have some survival gear around, including a good compass. But if you need your hands for other things, or simply don’t want to have to stop often to check a compass, you might want to try out something like this belt-mounted haptic feedback compass.

The compass is based around a Raspberry Pi Pico microcontroller and uses a ULN2803a transistor array chip to control a series of motors. The motors are mounted all along a belt using custom 3D printed clips with wires woven to each through the holes in the belt. The firmware running on the belt communicates with an Android app via USB to control each of the motor’s vibration based on the direction the wearer is traveling and their desired heading. With certain patterns, the wearer can get their correct heading based on the vibrations they feel through the belt.

While it does rely on having a functioning phone, a modern smartphone’s built-in compass doesn’t require a signal to work. We would still recommend having a good simple compass in your pack as backup if you’re going to be far off the beaten path, though. There are other ways of navigation besides by compass, map, or GPS too. Have a shot at inertial navigation if you want a challenge.

Thanks to [Peter] for the tip!

Testing An Inexpensive CNC Spindle

The old saying “you get what you pay for” is a cautionary cliché, but is directly contrary to several other common sayings. In the case of [Spikee]’s planned CNC machine build, he took the more adventurous idiom of “no risk, no reward” to heart when he purchased these spindles for the machine from AliExpress. While the delivered product seemed fine, there were some problems that needed investigations.

Upon delivery of the spindle, everything seemed to work correctly out-of-the-box. Even the variable frequency drive, which was programmed at the factory, was working properly. But at around 8000 rpm the machine would begin shaking. The suspected part causing the vibration was the tool holder, so after checking the machine’s runout and also using a specialized vibration sensor this was confirmed to be the case.

Luckily [Spikee] was able to get a refund on the tool holders since they were out of spec, but still has a quite capable spindle on his hands for an excellent price. Without some skills in troubleshooting he might have returned the entire machine unnecessarily. If you are looking for some other ideas in setting up an inexpensive CNC machine, you might also like to look at BLDC motors from a remote control vehicle.

Balancing A Motor With An Oscilloscope

With all things in life, one must seek to achieve balance. That may sound a little like New Age woo-woo, but if you think it’s not literally true, just try tolerating a washing machine with a single comforter on spin cycle, or driving a few miles on unbalanced tires.

Anything that rotates can quickly spin itself into shrapnel if it’s not properly balanced, and the DIY power tools in [Matthias Wandel]’s shop are no exception. Recent upgrades to his jointer have left the tool a bit noisy, so he’s exploring machine vibrations with this simple but clever setup. Using nothing but a cheap loudspeaker and an oscilloscope, [Matthias] was able to characterize vibrations in a small squirrel-cage blower — he wisely chose to start small to validate his method before diving into the potentially dangerous jointer. There was quite a lot to be learned from the complex waveforms coming back from the transducer, analysis of which was greatly helped by the scope’s spectrum analyzer function. The video below shows the process of probing various parts of the blower, differentiating spectral peaks due to electrical noise rather than vibration, and actually using the setup to dynamically balance the fan.

We’d rate this as yet another handy shop tip from [Matthias], and we’ll be looking out for the analysis of his jointer. Want to do the same but you don’t have an oscilloscope? No problem — an earbud and Audacity might be all you need.

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Does This Lead Make My Car Look Fat?

When looking at the performance of a vehicle, weight is one of the most important factors in the equation. Heavier vehicles take more energy to accelerate and are harder to stop. They’re also more difficult to control through the corners. Overall, anything that makes a vehicle heavier typically comes with a load of drawbacks to both performance and efficiency. You want your racecar as light as possible.

However, now and then, automakers have found reason to intentionally add large weights to vehicles. We’ll look at a couple of key examples, and discuss why this strange design decision can sometimes be just what the engineers ordered.

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