Day: October 20, 2024

DIY Air Bearings, No Machining Required

October 20, 2024 by No comments

Seeing a heavy load slide around on nearly frictionless air bearings is pretty cool; it’s a little like how the puck levitates on an air hockey table. Commercial air bearings are available, of course, but when you can build these open-source air bearings, why bother buying?

One of the nice things about [Diffraction Limited]’s design is that these bearings can be built using only simple tools. No machining is needed past what can be easily accomplished with a hand drill, thanks to some clever 3D-printed jigs that allow you to drill holes with precision into stainless steel discs you can buy on the cheap. An extremely flat surface is added to the underside of these discs thanks to another jig, some JB Weld epoxy, and a sheet of float glass to serve as an ultra-flat reference. Yet more jigs make it easy to scribe air channels into the flat surface and connect them to the air holes through a bit of plaster of Paris, which acts as a flow restriction. The video below shows the whole process and a demo of the bearings in action.

[Diffraction Limited] mentions a few applications for these air bearings, but the one that interests us most is their potential use in linear bearings; a big CNC cutter using these air bearings would be pretty cool. We seen similar budget-friendly DIY air bearings before, including a set made from used graphite EDM electrodes.

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Figuring Out The Most Efficient Way To Reuse Bags Of Desiccant

October 20, 2024 by 7 Comments

Everyone knows those small bags of forbidden “Do not eat” candy that come with fresh rolls of FDM filament as well as a wide range of other products. Containing usually silica gel but sometimes also bentonite clay, these desiccant bags are often either thrown away or tossed into bags of FDM filament with a ‘adding one can’t hurt’ attitude. As [Stefan] over at CNC Kitchen recently figured out, adding an already saturated bag of desiccant into e.g. an airtight container with a freshly dried spool of filament can actually make the humidity in the container spike as the desiccant will start releasing moisture. So it’s best to dry those little bags if you intend to reuse them, but what is the best way?

Among the ‘safe’ contenders are an oven, a filament dryer and the ‘filament drying’ option of [Stefan]’s Bambu Lab FDM printer. These managed to remove most of the moisture from the desiccant in a few hours. The more exciting option is that of a microwave, which does the same in a matter of minutes, requiring one or more ~5 minute sessions at low power, which effectively also used less power than the other options. Among the disadvantages are potentially melting bags, silica beads cracking, the bentonite clay desiccant heating up rather dangerously and the indicator dye in silica beads may be damaged by the rapid heating.

After all of this testing, it would seem that there are many good options to reuse those desiccant bags with a bit of care, although for those who happen to have a vacuum chamber nearby, that might be an even faster option.

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A Parts Bin MIDI Controller In 24 Hours

October 20, 2024 by 4 Comments

Part of the reason MIDI has hung on as a standard in the musical world for so long is that it is incredibly versatile. Sure, standard instruments like pianos and drums can be interfaced with a computer fairly easily using this standard, but essentially anything can be converted to a MIDI instrument with the right wiring and a little bit of coding. [Jeremy] needed to build a MIDI controller in a single day, and with just a few off-the-shelf parts he was able to piece together a musical instrument from his parts bin.

The build is housed in an off-brand protective case from a favorite American discount tool store, but the more unique part of the project is the choice to use arcade buttons as the instrument’s inputs. [Jeremy] tied eight of these buttons to an Arduino Uno to provide a full octave’s worth of notes, and before you jump to the comments to explain that there are 12 notes in an octave, he also added a button to the side of the case to bend any note when pressed simultaneously. An emergency stop button serves as a master on/off switch and a MIDI dongle on the other side serves as the interface point to a computer.

After a slight bit of debugging, the interface is up and running within [Jeremy]’s required 24-hour window. He’s eventually planning to use it to control a custom MIDI-enabled drum kit, but for now it was fun to play around with it in some other ways. He’s also posted the project code on a GitHub page. And, if this looks a bit familiar, this was not [Jeremy]’s first MIDI project. He was also the creator of one of the smallest MIDI interfaces we’ve ever seen.

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Forget Flipper, How About Capybara?

October 20, 2024 by 13 Comments

One of the hacker toys to own over the last year has been the Flipper Zero, a universal wireless hacking tool which even caused a misplaced moral panic about car theft in Canada. A Flipper is cool as heck of course but not the cheapest of devices. Fortunately there’s now an alternative in the form of the CapybaraZero. It’s a poor-hacker’s Flipper Zero which you can assemble yourself from a heap of inexpensive modules.

At the centre is an ESP32-S3 board, which brings with it that chip’s wireless and Bluetooth capabilities. To that is added an ST7789 TFT display, a PN532 NFC reader, an SX1276 LoRa and multi-mode RF module, and an IR module. The firmware can be found through GitHub. Since the repo is nearly two years old and still in active development, we’re hopeful CapybaraZero will gain features and stability.

If you’re interested in our coverage of the Canadian Flipper panic you can read it here, and meanwhile if you’re using one of those NFC modules, consider tuning it.

Behold A First-Person 3D Maze, Vintage Atari Style

October 20, 2024 by 5 Comments

[Joe Musashi] was inspired by discussions about 3D engines and decided to create a first-person 3D maze of his own. The really neat part? It could have been done on vintage Atari hardware. Well, mostly.

He does admit he had to do a little cheating to make this work; he relies on code for the ARM processor in the modern Atari VCS do the ray casting work, and the 6507 chip just handles the display kernel. Still, running his demo on a vintage Atari 2600 console could be possible, but would definitely require a Melody or Harmony cartridge, which are special reprogrammable cartridges popular for development and homebrew.

Ray casting is a conceptually simple method of generating a 3D view from given perspective, and here’s a tutorial that will tell you all you need to know about how it works, and how to implement your own.

[Joe]’s demo is just a navigable 3D maze rather than a game, but it’s pretty wild to see what could in theory have run on such an old platform, even if a few modern cheats are needed to pull it off. And if you agree that it’s neat, then hold onto your hats because a full 3D ray casting game — complete with a micro physics engine — was perfectly doable on the Commodore PET, which even had the additional limitation of a monochrome character-based display.