Mixapps: The Mixtape Of The Internet Age

Mixtapes used to be a way that we cultivated a personal selection of music for our own enjoyment, or to give as gifts to those we wanted to impress with a personal touch. These days, we’d typically try that with a playlist, but it’s less romantic despite also being more ephemeral. Songs fall off streaming services all the time, and few of us have the exact same subscriptions as those we’re trying to flirt with. Thus, [Hunter Irving] whipped up a more lasting solution for this modern age.

The concept is simple—it’s a collection of songs that are packaged together in a easily portable format that won’t disappear because of corporate bureaucratic nonsense. [Hunter] has termed their project Mixapps—because it’s a method of sharing music based around Progressive Web Apps (PWA). To create a custom mix, you start by running a Python script, which will then let you add tracks and reorder them as you desire. From there, you run a second script that builds the web app for you.

You can then upload the prepared app directory to a web host to share it with anyone you like. They can then save the PWA to the home screen of their mobile device, where it will live happily ever after. There’s no need to keep hosting the app online or for the user to remain connected to the Internet; everything is self contained on their device. If you’re curious, there’s a demo you can check out online.

It’s worth noting that there are intellectual property concerns to be had as with any form of music sharing, but what else is new? We’ve explored the magic of mixtapes in the past, anyway, to be sure. If you’re finding new ways to trade music and playlists, romantically or platonically, don’t hesitate to let us know.

Building A Die Filer From Scratch

A die filer is a useful tool to have if you find yourself filing parts on the regular. It’s basically a machine that reciprocates a file up and down for you so you can focus on filing the part to your desired dimensions. They’re not commonly manufactured these days, so [Richard Huberjohn] set about building his own. 

This die filer relies on a simple mechanism to turn rotational motion from a motor into reciprocating linear motion in the vertical plane. A rotating shaft is connected to a crank, which turns a pin in a slotted carrier attached to a linear bearing. As the wheel turns, the pin slides in the carrier, driving it and the linear rod up and down in turn. Attach a file to this, and you have a working die filer. In this case, the rotating shaft is driven by a pair of DC brushed motors, with output stepped down via a gearbox and then a short belt drive. Speed is varied with the aid of an off-the-shelf controller.

If you’re regularly filing small parts, a build like this could speed your work to a great degree. We’ve featured other DIY machine tool builds before, too. If you’re cooking up your own gear for the home workshop, don’t hesitate to let us know on the tipsline!

Using A Nintendo Switch To Speed Up A 3D Printer

3D printers are almost never fast enough. [Cocoanix] had a Prusa MK3S with this very problem. He found it to be disappointingly tedious when completing even simple prints, and sought a way to make it faster. Thus, he grabbed a Nintendo Switch and got to work.

It might sound like an odd choice, and that’s because it is. There’s no special magic inside a Nintendo Switch that makes 3D printers faster – it’s just that the handheld console was a useful platform on which to run Klipper. As [Cocoanix] explains, Klipper is designed to run on faster general-purpose computers compared to the more limited microcontrollers used in some printers. It’s designed to off-load complex motion processing tasks to a faster CPU, while the printer’s onboard microcontrollers are freed up to simply handle the low-level tasks of driving the motors and so on. An older printer equipped with Klipper can often print faster, while implementing techniques like input shaping to further improve speed as well as print quality.

It’s worth noting that you don’t have to use a Nintendo Switch for this. It’s just a good hook for the YouTube video. Typically you’d use a Raspberry Pi or some other computer instead, but the fact it runs on a jailbroken console is amusing nonetheless. It’s also cool to see the results – in this video, [Cocoanix] got the Benchy printing time down from 90 minutes to just 8.

We’ve previously discussed the benefits of Klipper at length.

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Mix Your Own ECN-2 Development Chemicals

After the digital camera rose to prominence, it became a cool hobby to keep taking photos on film. It was even cooler if you did the same with an old motion picture camera. The retro film revival has kept a dedicated bunch of photo labs in business over the years, but it’s still possible to save some cash on development by doing it yourself. If that’s your game, you might try mixing up your own development chemicals. 

As explained by [No Grain No Gain], it’s quite possible to mix up your own ECN-2 chemistry from scratch if you know what you’re doing. ECN-2 is the chemistry you’ll want if you’re trying to develop any of Kodak’s Vision3 films, along with CineStill films.

The problem with traditional methods of making developer is that once it’s mixed up, it doesn’t keep well, and the more you use it, the worse the quality gets. To beat this problem, this method involves producing two stock solutions which can be kept on the shelf for long periods of time. They can then be combined together with a little CD-3 developer on an as-needed basis. This makes it easy to always have fresh developer on hand for the best possible results on every roll processed. To make everything, you’ll need sodium sulfite, potassium bromide, sodium carbonate, sodium bicarbonate, and the specialist CD-3 developing agent. It’s then a simple job to mix up the dry chemicals with a bunch of distilled water to make the two necessary solutions to keep on hand. The video also explains how to deal with RemJet films if you happen to be shooting those.

[No Grain No Gain] estimates that this method can cut the cost of development to as little as 50 cents a roll. There’s plenty of labor involved, but if you want the freshest, best developer on hand for your home lab, it’s a method worth considering.

We’ve explored modern film development techniques before, too. Video after the break.

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DIY Electrolysis Machine Removes Hair Permanently

If you talk to the FDA, there’s only one permanent method of hair removal—electrolysis. This involves sticking a needle into a hair follicle, getting it very hot or running a current through it, and then letting heat and/or the lye generated kill the root of the hair dead. Normally, you’d pay someone with a commercial machine to do this for you at great expense. Or, you could do it yourself with a home-built machine, as [n3tcat] did.

Based on the available information out in the wild, [n3tcat] decided to build a galvanic electrolysis machine. This specifically passes current through a needle in the hair follicle to generate lye at the hair bulb, which kills it. The amount of lye generated depends on the amount of current and the time over which it is applied. More lye is more likely to kill a follicle permanently, though there are limits with regards to avoiding scarring, other skin damage, and excessive pain.

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How Giant Tanks Of Fluid Could Help Support The Power Grid

If you’ve been paying any attention to the renewable energy space, you’ll know that generation isn’t really the problem anymore. Solar panels are cheap, and wind turbines are everywhere. The problem is matching generation with demand—sometimes there’s too much wind and sun, and sometimes there’s not enough. Ideally, you could store that energy somewhere, and deploy it when you need it.

The answer everyone keeps reaching for is lithium-ion batteries, and they work just fine. However, there’s a competing technology that’s been quietly scaling up in the background—the vanadium flow battery. It has some unique advantages that could see it rise to prominence in the world of large-scale grid storage.

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Camera Slider: Build Instead Of Buy Goes Awry

[TheHyperFix] had a problem. He’d spied a brilliant camera slider, but didn’t want to lay out big money to acquire it. The natural solution? Build one! Only, life is seldom so straightforward.

The plan was straightforward – take an old broken 3D printer, and repurpose its parts to make a camera slider instead. The build started with a aluminium extrusion, some V-slot wheels, and a 3D printed platform to hold the camera. Moving the platform was done via a belt drive, using the stepper motors and some software to tell the original printer controller what to do.

Unfortunately, the early experiments failed when the controller blew up under load. An Arduino was subbed in with a CNC shield, which got things back on track, and [TheHyperFix] had a somewhat functional slider with relatively jerky movement. A tough iterative design process ensued to work out problems with bearings and the Arduino’s pulse limit, among others.

As it stands, the slider is semi-functional, but it’s not quite well behaved enough to use for professional shooting. Still, for a first attempt at electronics prototyping, we think [TheHyperFix] did a pretty solid job. It might not be all there yet, but it’s well on the way, and a great deal was learned in the process.

If you’re trying to build a camera slider in a hurry, you might like to try recreating one of the builds we’ve featured before. Video after the break.

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