Busted: Toilet Paper As Solder Wick

It didn’t take long for us to get an answer to the question nobody was asking: Can you use toilet paper as solder wick? And unsurprisingly, the answer is a resounding “No.”

Confused? If so, you probably missed our article a few days ago describing the repair of corroded card edge connectors with a bit of homebrew HASL. Granted, the process wasn’t exactly hot air solder leveling, at least not the way PCB fabs do it to protect exposed copper traces. It was more of an en masse tinning process, for which [Adrian] used a fair amount of desoldering wick to pull excess solder off the pins.

During that restoration, [Adrian] mentioned hearing that common toilet paper could be used as a cheap substitute for desoldering wick. We were skeptical but passed along the tip hoping someone would comment on it. Enter [KDawg], who took up the challenge and gave it a whirl. The video below shows attempts to tin a few pins on a similar card-edge connector and remove the excess with toilet paper. The tests are done using 63:37 lead-tin solder, plus and minus flux, and using Great Value TP in more or less the same manner you’d use desoldering braid. The results are pretty much what you’d expect, with charred toilet paper and no appreciable solder removal. The closest it comes to working is when the TP sucks up the melted flux. Stay tuned for the bonus positive control footage at the end, though; watching that legit Chemtronics braid do its thing is oddly satisfying.

So, unless there’s some trick to it, [KDawg] seems to have busted this myth. If anyone else wants to give it a try, we’ll be happy to cover it.

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Flux, From Scratch

Soldering flux is (or at least, should be) one of the ubiquitous features of any electronics bench. It serves the purpose of excluding oxygen from a solder joint as it solidifies, and in most cases its base is derived from pine rosin. Most of us just buy flux, but [pileofstuff] is having a go at making his own.

He starts with a block of rosin and a couple of different solvents. Isopropanol we’re happy with, but perhaps using methanol for something to be vaporized within breathing distance isn’t something we’d do. At about 25% rosin to solvent ratio the result is a yellow liquid flux, which he tests against some commercial fluxes. The result is a reasonable liquid flux, something which perhaps shouldn’t be too much of a surprise, and is a handy piece of information to store away should we ever be MacGuyver-like stuck in a pine forest with a need to save the day with electronics.

It would be interesting to try the same technique but with a solvent selected to soften the rosin for a paste flux, and perhaps any chemists among our readership could enlighten us about just what rosin is beside the heavy fractions left after extracting the volatiles from pine resin.

In the past we’ve taken a close look at how solder really works.

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Retrotechtacular: The Story Of Turpentine

If someone in 2023 has ever had much call to use turpentine, chances are good it was something to do with paint or other wood finishes, like varnish. Natural turpentine is the traditional solvent of choice for oil paints, which have decreased in popularity with the rise of easy-to-clean polymer-based paints and coating. Oh sure, there are still those who prefer oil paint, especially for trim work — it lays up so nice — but by and large, turpentine seems like a relic from days gone by, like goose grease and castor oil.

It wasn’t always so, though. Turpentine used to be a very big deal indeed, as shown by this circa 1940 documentary on the turpentine harvesting and processing industry. Even then it was only a shadow of its former glory, when it was a vital part of a globe-spanning naval empire and a material of the utmost strategic importance. “Suwanee Pine” shows the methods used in the southern United States, where fast-growing pines offer up a resinous organic gloop in response to wounds in their bark. The process shown looks a lot like the harvesting process for natural latex, with slanting gashes or “catfaces” carved into the trunks of young trees, forming channels to guide the exudate down into a clay collecting cup.

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Magnetic Gearbox, Part 2: Axial Flux Improves Performance

The number of interesting and innovative mechanisms that 3D printing has enabled always fascinates us, and it’s always a treat when one of them shows up in our feeds. This axial flux magnetic gearbox is a great example of such a mechanism, and one that really makes you think about possible applications.

The principles of [Retsetman]’s gearbox are simple for anyone who has ever played with a couple of magnets to understand, since it relies on that powerful attractive and repulsive force you feel when magnets get close to each other. Unlike his previous radial flux gearbox, which used a pair of magnet-studded cylindrical rotors nested one inside the other, this design has a pair of disc-shaped printed rotors that face each other on aligned shafts. Each rotor has slots for sixteen neodymium magnets, which are glued into the slots in specific arrangements of polarity — every other magnet for the low-speed rotor, and groups of four on the high-speed rotor. Between the two rotors is a fixed flux modulator, a stator with ten ferromagnetic inserts screwed into it.

In operation, which the video below demonstrates nicely, the magnetic flux is coupled between the rotors by the steel inserts in the stator so that when one rotor moves, the other moves at a 4:1 (or 1:4) ratio in the opposite direction. [Retsetman] got the gearbox cranked up to about 8,500 RPM briefly, but found that extended operation at as little as 4,000 RPM invited disaster not due to eddy current heating of the inserts or magnets as one might expect, but from simple frictional heating of the rotor bearings.

Torque tests of the original gearbox were unimpressive, but [Retsetman]’s experiments with both laminated stator inserts and more powerful magnets really boosted the output — up to a 250% improvement! We’d also like to see what effect a Halbach array would have on performance, although we suspect that the proper ratios between the two rotors might be difficult to achieve.

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Whip Up Some Homemade Artisanal Flux

You don’t think much about the power company until you flip the lights on and they don’t come on. The same can be said of soldering flux. You don’t think much about it, usually, until you try soldering without it. Flux has a cleaning action on metal surfaces that allows for a proper solder joint. The problem is, do you have any idea what’s in the flux you are using? We don’t either. [Catsndogs] has a recipe to make your own flux and then you’ll know.

At the heart of rosin flux is basically tree sap. If you live near pine trees, you can source it naturally. If not, you can find it at music instrument stores. Stringed instruments use rosin, so it is readily available. If you do source it yourself, [Catsndogs] reports that it doesn’t matter if it is old or clean.  You do want to pick out as much tree bark and dead ants as you can, though. You essentially dissolve it in alcohol (at least 80% isopropyl or ethanol). Then filter it through filter paper or a coffee filter.

You can adjust the viscosity by allowing the alcohol to evaporate to make the mixture thicker or by adding more alcohol to make it thinner. Thicker flux is good for tacking down SMD parts. As you might expect, this isn’t “no clean” flux. Also, the flux is very flammable, so be careful.

This isn’t the first time we’ve heard of this recipe. Or even the second time. But it is a good reminder that you can make your own free of whatever wacky chemicals are in the commercial preparations.

Magnetic Gearbox Design Improvements Are Toothless But Still Cool

Any project that contains something called a “flux modulator” instantly commands our attention. And while we’re pretty sure that [Retsetman] didn’t invent it after hitting his head on the toilet, this magnetic gearbox is still really cool.

Where most gearboxes have, you know, gears, a magnetic gearbox works by coupling input and output shafts not with meshing teeth but via magnetic attraction. [Retsetman]’s version has three circular elements nested together on a common axis, and while not exactly a planetary gear in the traditional sense, he still uses planetary terminology to explain how it works. The inner sun gear is a rotor with four pairs of bar magnets on its outer circumference. An outer ring gear has ten pairs of magnets, making the ratio of “teeth” between the two gears 10:2. Between these two elements is the aforementioned flux modulator, roughly equivalent to the planet gears of a traditional gearbox, with twelve grub screws around its circumference. The screws serve to conduct magnetic flux between the magnets, dragging the rotating elements along for the ride.

This gearbox appears to be a refinement on [Retsetman]’s earlier design, and while he provides no build files that we can find, it shouldn’t be too hard to roll your own designs for the printed parts.

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Floppy disks

Floppy Interfacing Hack Chat With Adafruit

Join us on Wednesday, February 2 at noon Pacific for the Floppy Interfacing Hack Chat with Adafruit’s Limor “Ladyada” Fried and Phillip Torrone!

When a tiny fleck of plastic-covered silicon can provide enough capacity to store a fair percentage of humanity’s collected knowledge, it may seem like a waste of time to be fooling around with archaic storage technology like floppy disks. With several orders of magnitude less storage capacity than something like even the cheapest SD card or thumb drive, and access speeds that clock in somewhere between cold molasses and horse and buggy, floppy drives really don’t seem like they have any place on the modern hacker’s bench.

join-hack-chatOr do they? Learning the ins and out of interfacing floppy drives with modern microcontrollers is at least an exercise in hardware hacking that can pay dividends in other projects. A floppy drive is, after all, a pretty complex little device, filled with electromechanical goodies that need to be controlled in a microcontroller environment. And teasing data from a stream of magnetic flux changes ends up needing some neat hacks that might just serve you well down the line.

So don’t dismiss the humble floppy drive as a source for hacking possibilities. The folks at Adafruit sure haven’t, as they’ve been working diligently to get native floppy disk support built right into CircuitPython. To walk us through how they got where they are now, Ladyada and PT will drop by the Hack Chat. Be sure to come with your burning questions on flux transitions, MFM decoding, interface timing issues, and other arcana of spinning rust drives.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 2 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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