Author: Bryan Cockfield

1555 Articles

An IPhone Case Study

December 15, 2024 by 14 Comments

Way back in 2008, Apple unveiled the first unibody Macbook with a chassis milled out of a single block of aluminum. Before that, essentially all laptops, including those from Apple, were flimsy plastic screwed together haphazardly on various frames. The unibody construction, on the other hand, finally showed that it was possible to make laptops that were both lightweight and sturdy. Apple eventually began producing iPhones with this same design style, and with the right tools and a very accurate set of calipers it’s possible to not only piece together the required hardware to build an iPhone from the ground up but also build a custom chassis for it entirely out of metal as well.

The first part of the project that [Scotty] from [Strange Parts] needed to tackle was actually getting measurements of the internals. Calipers were not getting the entire job done so he used a flatbed scanner to take an image of the case, then milled off a layer and repeated the scan. From there he could start testing out his design. After an uncountable number of prototypes, going back to the CAD model and then back to the mill, he eventually settles into a design but not before breaking an iPhone’s worth of bits along the way. Particularly difficult are the recessed areas inside the phone, but eventually he’s able to get those hollowed out, all the screw holes tapped, and then all the parts needed to get a working iPhone set up inside this case.

[Scotty] has garnered some fame not just for his incredible skills at the precision mill, but by demonstrating in incredible detail how smartphones can be user-serviceable or even built from scratch. They certainly require more finesse than assembling an ATX desktop and can require some more specialized tools, but in the end they’re computers like any other. For the most part.

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A Portable Chainsaw Sawmill

December 14, 2024 by 25 Comments

Unless you’re running a commercial logging operation, with specialized saws, log grapples, mills, transportation for the timber, and the skilled workers needed to run everything, it’s generally easier to bring a sawmill to the wood instead of taking the wood to the sawmill. Especially for a single person, something like a chainsaw mill is generally a much easier and cost effective way to harvest a small batch of timber into lumber. These chainsaw mills can still be fairly cumbersome though, but [izzy swan] has a new design that fits an entire mill onto a hand cart for easy transportation in and out of a forest.

The entire mill is built out of a sheet and a half of plywood, most of which is cut into strips and then assembled into box girders for the track. The remainder of plywood is machined on a CNC to create the carriage for the chainsaw to attach as well as a few other parts to fix the log in place. The carriage has a 4:1 reduction gear on it to winch the chainsaw along the length of the log which cuts the log into long boards. After the milling is complete, the entire mill can be disassembled and packed down onto its hand cart where it can be moved on to the next project fairly quickly.

For a portable mill, it boasts respectable performance as well. It can cut logs up to 11 feet in length and about 30 inches across depending on the type of chainsaw bar used, although [izzy swan] has a few improvements planned for the next prototypes that look to make more consistent, uniform cuts. Chainsaws are incredibly versatile tools to have on hand as well, we’ve seen them configured into chop saws, mortisers, and even fixed to the end of a CNC machine.

Thanks to [Keith] for the tip!

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Apple Newton Gets Rebuilt Battery Pack

December 13, 2024 by 14 Comments

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

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Chaotic System Cooks Meat Evenly

December 11, 2024 by 35 Comments

For better or worse, a lot of human technology is confined to fewer dimensions than the three we can theoretically move about in. Cars and trains only travel two dimensionally with limited exceptions, maps and books generally don’t take advantage of a third dimension, and most computer displays and even the chips that make them work are largely two-dimensional in nature. Most styles of cooking can only apply heat in a single dimension as well, but [Dane Kouttron] wanted to make sure the meat his cookouts took advantage of a truly three-dimensional cooking style by adding a gyroscopic mechanism to the spit.

The first thing that needed to be built were a series of concentric rings for each of the three axes of rotation. Metal tubes were shaped with a pipe bender and then welded into their final forms, with an annealing step to flatten the loops. From there, the rings are attached to each other with a series of offset bearings. The outer tube is mounted above the fire and a single motor spins this tube. Since no piece of meat is perfectly symmetrical (and could be offset on the interior ring a bit even if it were) enough chaos is introduced to the system that the meat is free to rotate in any direction, change direction at any time, and overall get cooked in a more uniform way than a traditional single-dimensional rotating spit.

As a proof of concept [Dane] hosted a cookout and made “gyro” sandwiches (even though the machine may technically be more akin to a gimbal), complete with small Greek flag decorative garnishes. It seems to have been a tremendous success as well. There are a few other novel ways we’ve seen of cooking food over the years, including projects that cook with plasma and much more widely available methods that cook food efficiently using magnets, of a sort.

Amateur Radio Operators Detect Signals From Voyager 1

December 11, 2024 by 40 Comments

At the time of its construction in the 1950s, the Dwingeloo Radio Observatory was the largest rotatable telescope in the world with a dish diameter of 25 meters. It was quickly overtaken in the rankings but was used by astronomers for decades until it slowly fell into disuse in the early 2000s. After a restoration project the telescope is now a national heritage site in the Netherlands where it is also available for use by radio amateurs. Recently this group was able to receive signals from Voyager 1.

Famously, Voyager 1 is the furthest manmade object from Earth, having been launched on a trajectory out of the solar system in 1977. As a result of distance and age, the signals it sends out are incredibly faint. The team first had to mount a new antenna to the dish, which was not originally designed for signals in this frequency which added to the challenge. They then needed to use orbital predictions of the spacecraft in order to target the telescope and also make the correct adjustments to the received signal given that there is significant Doppler shift now as well. But with that all out of the way, the team was successfully able to receive the Voyager 1 signal on this telescope.

Only a few telescopes in the world have ever been able to accomplish this feat, making it all the more impressive. Normally Voyager 1 is received using the Deep Space Network, a fleet of much larger dishes stationed around the world and designed for these frequencies. But this team is used to taking on unique challenges. They also decoded the first ham radio station on the moon and made a radar image of the moon using LoRa.

Dwingeloo telescope receives signals from Voyager 1

The Math Behind The Music Of The 80s

December 11, 2024 by 51 Comments

Although there might have been other music produced or recorded in the 1980s, we may never know of its existence due to the cacophony of all of the various keytars, drum machines, and other synthesized music playing nonstop throughout the decade. There was perhaps no more responsible synthesizer than the Yamaha DX7 either; it nearly single-handedly ushered in the synth pop era. There had been other ways of producing similar sounds before but none were as unique as this keyboard, and for ways beyond just its sound as [Kevin] describes in this write-up.

Part of the reason the DX7 was so revolutionary was that it was among the first accessible synthesizers that was fully digital, meaning could play more than one note at a time since expensive analog circuitry didn’t need to be replicated for multiple keys. But it also generated its tones by using frequency modulation of sine waves in a way that allowed many signals to be combined to form different sounds. While most popular musicians of the 80s used one of the preset sounds of the synthesizer, it could produce an incredible range of diverse sounds if the musician was willing to dig a bit into the programming of this unique instrument.

There were of course other reasons this synthesizer took off. It was incredibly robust, allowing a musician to reliably carry it from show to show without much worry, and it also stood on the shoulders of giants since musicians had been experimenting with various other types of synthesizers for the previous few decades. And perhaps it was at the right place and time for the culture as well. For a look at the goings on inside the chip that powered the device, [Ken Shirriff] did a deep dive into one a few years ago.

A Potential Exploit With The Ext Filesystem

December 10, 2024 by 58 Comments

The extended filesystem, otherwise known as ext, has been a fundamental part of Linux since before the 1.0 release in 1994. Currently the filesystem is on its fourth major revision, in use since its release in 2008 thanks to its stability, reliability, and backwards compatibility with the other ext filesystem versions. But with that much history there are bound to be a few issues cropping up here and there. [Will] recently found an exploit with this filesystem that can cause a Linux kernel to immediately panic when a manipulated USB drive is inserted into a computer.

[Will] discovered this quirk when investigating the intricacies of the filesystem for problems and other vulnerabilities. A tool called tune2fs, used for administering and modifying ext filesystems, includes the ability to pass certain commands to the Linux kernel when certain situations arise with the filesystem itself, including that the kernel should panic. One situation is that the ext filesystem itself becomes corrupted, which can then cause the kernel panic. Armed with this knowledge, a USB drive can be purposefully given a corrupted ext filesystem which, when plugged into a Linux machine, can cause the computer to shut down.

The post linked above goes into some discussion about how this exploit could be used maliciously to gain access to a Linux system, including rebooting computers where no access to a power button is otherwise enabled or making other changes to the system before needing a reboot to apply the changes. In general, though, it’s good to assume an attacker could take any route to gain access to a machine. This exploit from a few years ago, for example, allowed another Linux tool to be used to gain root access.

Thanks to [Timothy] for the tip!