CNC Plasma Cutter Filter Gets The Slag Out

May 16, 2020 by 10 Comments

No matter what kind of tools and materials you use in your shop, chances are pretty good that some process is going to release something that you don’t want to breathe. Table saw? Better deal with that wood dust. 3D-printer? We’ve discussed fume control ad nauseam. Soldering? It’s best not to inhale those flux fumes. But perhaps nowhere is fume extraction more important than in the metal shop, where vaporized bits of metal can wreak respiratory havoc.

Reducing such risks was [Shane Wighton]’s rationale behind this no-clean plasma cutter filter. Rather than a water table to collect cutting dross, his CNC plasma cutter is fitted with a downdraft table to suck it away. The vivid display of sparks shooting out of the downdraft fans belied its ineffectiveness, though. [Shane]’s idea is based on the cyclonic principle common to woodshop dust collectors and stupidly expensive vacuum cleaners alike. Plastic pipe sections, split in half lengthwise and covered in aluminum tape to make them less likely to catch on fire from the hot sparks, are set vertically in the air path. The pipes are arranged in a series of nested “S” shapes, offering a tortuous path to the spark-laden air as it exits the downdraft.

The video below shows that most of the entrained solids slow down and drop to the bottom of the filter; some still pass through, but testing with adhesive sheets shows the metal particles in the exhaust are much reduced. We like the design, especially the fact that there’s nothing to clog or greatly restrict the airflow.

Looking for more on CNC plasma cutter builds? We’ve got you covered, from just the basics to next-level.

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All About That Bass – Marble Machine X Keeps Growing

May 16, 2020 by 23 Comments

We’re okay if you call out Not A Hack™ on this one, because “hack” really doesn’t do justice to the creations of [Martin] from [Wintergatan]. You’re probably familiar with the Marble Machine that went viral a few years ago, and while it was impressive as-is back then, and most people would have declared the project finished at that point, it has turned into a seemingly never-ending work-in-progress project that has certainly come a long way ever since. Its latest addition: the Cyber Capos as upgrade for the bass, and you can find out all about it in its build video — also embedded below.

If you play a string instrument and ever used a capo — the clamping little helper device to smack the pitch up — you may have found yourself wishing that you could use it on any arbitrary fret on each string. Sure, there are partial capos and the spider capo to select individual strings, but you’re still limited to transpose along a single fret. Well, [Martin]’s Cyber Capos, a mechanical construct of four arms sliding along the neck, serve exactly that purpose, which allows him to free up his hands for other things while the marbles keep bouncing.

But you don’t have to be a bass player, or any musician really, to appreciate [Martin]’s build videos. We praised his general attitude and hacker-like spirit already the first time we mentioned the Marble Machine, and just watching him getting excited about his work and the appreciation for people supporting and assisting in the project, while embracing his mistakes, is a genuine delight.

Needless to say that [Martin] likes some uniqueness in music instruments, and the bass with its separate volume control and output for each string qualifies on its own for that. If you’re curious about more on that, there’s another video about it embedded after the break. And for the really impatient ones, you can see the capos in action in the first video around the 12:35 mark.

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Is It A Toy? A Prototype? It’s A Hack!

May 16, 2020 by 2 Comments

Some of the coolest hacks do a lot with a little. I was just re-watching a video from [Homo Faciens], who after building a surprisingly capable CNC machine out of junk-bin parts and a ton of ingenuity, was accidentally challenged by Hackaday’s own [Dan Maloney] to take it a step further. [Dan] was only joking when he asked “Can anyone build a CNC machine out of cardboard and paperclips?”, but then [Homo Faciens] replied: cardboard and paperclip CNC plotter. Bam!

My favorite part of the cardboard project is not just the clever “encoder wheel” made of a bolt dipped in epoxy, with enough scraped off that it contacts a paperclip once per rotation. Nor was it the fairly sophisticated adjustable slides and ways that he built to mimic the functionality of the real deal. Nope.

My favorite part of this project is [Norbert] explaining that the machine has backlash here, and it’s got play there, due to frame flex. It is a positive feature of the machine. The same flaws that a full-metal machine would have are all present here, but due to the cheesy construction materials, you can see them with the naked eye instead of requiring a dial indicator. Because it wiggles visible tenths of an inch where a professional mill would wiggle invisible thousandths, that helps you build up intuition for the system.

This device isn’t a “prototype” because there’s no way [Norbert] intends it for serious use. But it surely isn’t just a “toy” either. “Instructional model” makes it sound like a teaching aid, created by a know-it-all master, intended to be consumed by students. If anything, there’s a real sense of exploration, improvisation, and straight-up hacking in this project. I’m sure [Norbert] learned as much from the challenge as we did from watching him tackle it. And it also captures the essence of hacking: doing something unexpected with tech.

Surprise us!

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A Pulse Oximeter From Very Little

May 16, 2020 by 31 Comments

Against the backdrop of a global respiratory virus pandemic, it’s likely that more than a few readers have been thinking about pulse oximeters. You may even have looked at one closely and seen that it’s little more than a device which shines light through your finger, and wondered how they work. It’s something [Giulio Pons] has done, and to show us how it’s done he’s created a working pulse oximeter of his own.

He started with an infra-red heartbeat sensor module, which is revealed as nothing more than an IR LED and a photodiode. Sampling the output from the photodiode allows measurement of heartbeat, but gives not clue as to oxygen saturation. The interesting part comes via the property of red light in that it’s transmission through flesh varies with oxygen saturation, so adding a red LED and alternately measuring from the IR and red illuminations allows a saturation figure to be derived.

Commercial pulse oximeters are pretty cheap, so many of us will no doubt simply order one from the usual sources and call it good. But it’s always interesting to know how any device works, and this project reveals something simpler than we might have expected. If pulse oximeters interest you, compare it with this one we featured a few years ago.

The 19th Century, When Gravity Battery Meant Something Different

May 16, 2020 by 19 Comments

The internet is full of dubious content promoting “free energy” devices and other ideas that stretch credibility, so [Robert Murray-Smith] prefaces his demonstration of a gravity battery with a warning to look elsewhere if you are in search of such things. Instead he’s showing us a pair of cells from The Model Engineer and Amateur Electrician, a printed periodical that sounds to us something like an equivalent of Hackaday from the 1890s. (Video embedded below.)

The cells are termed gravity batteries because their constituents settle out into layers not unlike a tequila sunrise under the influence of gravity, something that made them especially suitable for the home constructor in the late 19th century when there were no handy wall outlets from which to snag a bit of power.

The chemistry of each is not unexpected if you spent any time in your high school’s lab, a zinc-copper primary cell with a zinc sulphate/copper sulphate electrolyte and a secondary zinc-carbon cell with a zinc bromide electrolyte and a layer of bromine forming on charging. The construction in large glass vessels is archaic though, and it’s this that’s prompted his video. He poses the question whether this type of cell might be revived using 21st century techniques to produce something of use today. The video is below the break, and even if you are not about to try your hand at electrochemistry it’s an interesting watch.

Thanks [Blaubär] for the tip! Continue reading “The 19th Century, When Gravity Battery Meant Something Different” →

EDSAC Lives In MiSTer

May 15, 2020 by 5 Comments

There’s a lot of argument over which was the first modern computer to be built. There’s room for debate, but EDSAC — the work of Dr. Maurice Wilkes — certainly was among the first. While we’ve seen simulators before, [hrvach’s] FPGA-based simulator for the MiSTer platform has a lot going for it. Check out the video, below.

So much of what we take for granted today was first developed on the EDSAC. For example, the “Wheeler jump” (named after graduate student David Wheeler) was the origin of the idea of a subroutine.

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DIY Neuralyzer From Scrap Parts

May 15, 2020 by 9 Comments

Cosplay and prop making are near and dear to our hearts here at Hackaday. That’s why whenever we see sci-fi tech brought to life, we can’t help but pay close attention. Enter [How to make’s] DIY Neuralyzer, from the Men-in-Black franchise. Unfortunately, this won’t wipe your memories as the real-life Neuralyzer would, but it will make for a cool prop at your next cosplay event.

What makes this project worth sharing is its use of very simple home tools and a bit of scrap metal, some PVC, a single LED, a switch, and maybe a few more miscellaneous bits. The base of the design is composed of two pieces of hollow, rod-shaped scrap metal and a single spring that mechanizes the entire setup.

The video is a few months old at this point. It took a recent post on Reddit to send this across our feed, but we’re glad we came across it.

Great project [How to make]! May we suggest a few more LEDs?

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