3D Printed CNC Knee Mill

July 13, 2021 by 52 Comments

CNC mills will never match real heavy metal mills on hard materials, but that won’t stop people from pushing the limits of these DIY machines. One of the usual suspects, [Ivan Miranda] is at it again, this time building a knee mill from aluminum extrusions and 3D printed fittings. (Video after the break.)

Most DIY CNC milling machines we see use a gantry arrangement, where the bed is fixed while everything else moves around it. On most commercial metal milling machines, the table is the moving part, and are known as knee mills. In the case of [Ivan]’s mill, the table can move 187 mm on the X-axis and 163 mm on the Y-axis. The 1.5 kW spindle can move 87 mm in the Z-axis. All axes slide on linear rails and are driven by large stepper motors using ball screws. The table can also be adjusted in the Z-direction to accept larger workpieces, and the spindle can be tilted to mill at an angle.

To machine metal as [Ivan] intended, rigidity is the name of the game, and 3D printed parts and aluminum extrusion will never be as rigid as heavy blocks of steel. He says claims that the wobble seen on the video is due to the uneven table on which the mill was standing. Of course, a wobbly base won’t be doing him any favors. [Ivan] also had some trouble with earthing on the spindle. He nearly set his workshop on fire when he didn’t notice tiny sparks between the cutter and aluminum workpiece while he was cooling it with isopropyl alcohol. This was solved with the addition of the grounding wire.

While the machine does have limitations, it does look like it can machine functional metal parts. It could even machine metal upgrades for its 3D printed components. One possible way to improve rigidity would be to cast the frame in concrete. [Ivan] has built several other workshop tools, including a massive 3D printer and a camera crane. Continue reading “3D Printed CNC Knee Mill” →

Muse Group Continues Tone Deaf Handling Of Audacity

July 13, 2021 by 133 Comments

When we last checked in on the Audacity community, privacy-minded users of the free and open source audio editor were concerned over proposed plans to add telemetry reporting to the decades old open source audio editing software. More than 1,000 comments were left on the GitHub pull request that would have implemented this “phone home” capability, with many individuals arguing that the best course of action was to create a new fork of Audacity that removed any current or future tracking code that was implemented upstream.

For their part, the project’s new owners, Muse Group, argued that the ability for Audacity to report on the user’s software environment would allow them to track down some particularly tricky bugs. The tabulation of anonymous usage information, such as which audio filters are most commonly applied, would similarly be used to determine where development time and money would best be spent. New project leader Martin “Tantacrul” Keary personally stepped in to explain that the whole situation was simply a misunderstanding, and that Muse Group had no ill intent for the venerable program. They simply wanted to get a better idea of how the software was being used in the real-world, but after seeing how vocal the community was about the subject, the decision was made to hold off on any changes until a more broadly acceptable approach could be developed.

Our last post on the subject ended on a high note, as it seemed like the situation was on the mend. While there was still a segment of the Audacity userbase that was skeptical about remote analytics being added into a program that never needed it before, representatives from the Muse Group seemed to be listening to the feedback they were receiving. Keary assured users that plans to implement telemetry had been dropped, and that should they be reintroduced in the future, it would be done with the appropriate transparency.

Unfortunately, things have only gotten worse in the intervening months. Not only is telemetry back on the menu for a program that’s never needed an Internet connection since its initial release in 2000, but this time it has brought with it a troubling Privacy Policy that details who can access the collected data. Worse, Muse Group has made it clear they intend to move Audacity away from its current GPLv2 license, even if it means muscling out long-time contributors who won’t agree to the switch. The company argues this will give them more flexibility to list the software with a wider array of package repositories, a claim that’s been met with great skepticism by those well versed in open source licensing.

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The Linux Kernel 5.14 Audio Update

July 13, 2021 by 39 Comments

You may remember the Pipewire coverage we ran a couple weeks ago, and the TODO item to fix up Firewire device support with Pipewire. It turns out that this is an important feature for kernel hackers, too, because the Alsa changes just got pulled into the 5.14 kernel, and included is the needed Firewire audio work. Shout-out to [Marcan] for pointing out this changeset. Yes, that’s the same as [Hector Martin], the hacker bringing Linux to the M1, who also discovered M1racles. We’ve covered some of his work before.

It turns out that some Firewire audio devices expect timing information in the delivery stream to match the proper playback time for the audio contained in the stream. A naive driver ends up sending packets of sound to the Firewire device that wanted to be played before the packet arrives. No wonder the devices didn’t work correctly. I’m running a 5.14 development kernel, and so far my Focusrite Saffire Pro40 has been running marvelously, where previous kernels quickly turned its audio into a crackling mess.

There is another fix that’s notable for Pipewire users, a reduction in latency for USB audio devices. That one turned out to be not-quite-correct, leading to a hang in the kernel on Torvald’s machine. It’s been reverted until the problem can be corrected, but hopefully this one will land for 5.14 as well. (Edit: The patch was cleaned up, and has been pulled for 5.14. Via Phoronix.) Let us know if you’d like to see more kernel development updates!

RevK_NFC-Reader_v2-Photo

NFC Who’s At The Door

July 13, 2021 by 8 Comments
RevK_NFC_v1-Prototype-Photo
An early prototype that worked on the first try, except for one LED

[RevK] wanted to learn about NFC readers, and we agree that the best way to do so is to dive in and build one yourself.

There are readers available from multiple sources, but [RevK] found them either compact but with no prototyping space or plenty of prototyping space and a large footprint. High-speed UART (HSU) was selected over I2C for communication with an ESP32 as testing showed it was just as fast and more reliable over long distances at the cost of only one additional wire.

After a few versions, the resulting PN532 based NFC reader has just enough GPIO for a doorbell and tamper switch and three status LEDs, with board files and a 3D-printed case design included in the open source project on GitHub. When looking into the project, we appreciated learning about tamper switches that can include closed or open contact status when an NFC is read, most often used in the packaging of high-value and collectible products. If you have worked with this tamper feature of NFCs, let us know about it.

Thanks for the tip, [Simon]

Human-Following Utility Trailer

July 12, 2021 by 27 Comments

[Théo Gautier] thought that a human-following utility trailer would be helpful for people working on farms. He didn’t just think about it, however, he designed and built it as a final project at the Agrilab FabAcademy at the University UniLasalle Polytechnique in northern France. He took the idea from concept to fruition in six weeks.

His build log documents the project very well, and takes you through his design choices and their implementation. The brains of the cart are a SAMD21E board that he made himself, and its sensory perception of the world is provided by HC-SR04 ultrasonic sensors and a PixyCam 2. Locomotion is provided by four each 100W DC motor / gearbox assemblies. He’s put a lot of effort into the construction process and posted a lot of photos of the intermediate steps. One piece of advice that caught our eye was to measure the diagonals of your frame repeatedly when welding it together — things can and do shift around. If you don’t, you may have to rectify the mistake like [Théo] did, with a big hammer.

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High-Tech Paperweight Shows Off Working 60s-era Thin-Film Electronics

July 12, 2021 by 9 Comments

[Ken Shirriff]’s analysis of a fascinating high-tech paperweight created by GE at the height of the space race is as informative as it is fun to look at. This device was created to show off GE’s thin-film electronics technology, and while it’s attractive enough on its own, there’s an added feature: as soon as the paperweight is picked up, it begins emitting a satellite-like rhythmic beep. It is very well-made, and was doubtlessly an impressive novelty for its time. As usual, [Ken] dives into what exactly makes it tick, and shares important history along the way.

Thin-film module with labels, thanks to [Ken]’s vintage electronics detective work. Click to enlarge.
In the clear area of the paperweight is a thin-film circuit, accompanied by a model of an early satellite. The module implements a flip-flop, and the flat conductors connect it to some additional components inside the compartment on the left, which contains a power supply and the necessary parts to create the beeps when it is picked up.

Thin-film electronics reduced the need for individual components by depositing material onto a substrate to form things like resistors and capacitors. The resulting weight and space savings could be considerable, and close-ups of the thin film module sure look like a precursor to integrated circuits. The inside of the left compartment contains a tilt switch, a battery, a vintage earphone acting as a small speaker, and a small block of components connected to the thin-film module. This block contains two oscillators made with unijunction transistors (UJTs); one to create the beep, and one to control each beep’s duration. The construction and overall design of the device is easily recognizable, although some of the parts are now obsolete.

If you’d like a bit more detail on exactly how this device worked, including circuit diagrams and historical context, be sure to click that first link, and pay attention to the notes and references at the end. One other thing that’s clear is that functional electronics embedded in clear plastic shapes simply never go out of style.

Revolving Plant Tower Is Solar-Powered

July 12, 2021 by 16 Comments

Do you live in a small or yard-less space, but want to grow things anyway? You’re not totally out of luck — you’ll just have to get creative and probably vertical with your planting scheme. And since apartments and other smallish dwellings often have a limited amount of exposure, it would really help a lot if you could somehow rotate the plants so that they receive even sunlight.

[JT_Makes_It]’s rotating strawberry tower ticks all these boxes and more. The 12 V solar cell powers a small DC motor that spins at the gentle speed of 0.6 RPM. The tube is hanging from a swiveling carabiner that acts like a clutch — if a strong wind comes along or something bumps into it, the motor will continue to spin the carabiner.

[JT_Makes_It] already had a tube with holes, though they did cut several more into it. As built, this is not exactly apartment dweller-friendly, unless you have off-site access to things like plasma cutters and welding equipment. But as they point out, you could theoretically use PVC and a hole saw and make it shorter and therefore lighter. We think this looks great, although we’re a bit concerned about the weight. Not so much on the mechanism itself; that looks strong. We’re just wondering how long that carport frame will support it. Judge the build quality for yourself from the video after the break.

Did you know that strawberries can do tricks? Fasciation makes fanned-out berries, and vivipary makes them hairy.

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