Stack N’ Rack Your Hardware With The HomeRacker Project

November 27, 2025 by Donald Papp 4 Comments

Things are cooler when rack-mounted, and [KellerLab] aims to make that all far more accessible with the HomeRacker, a modular and 3D-printable rack building system designed to let you rack-mount to your heart’s content. While it can handle big things, it seems especially applicable to tasks like mounting one’s home network equipment and Raspberry Pi machines.

A rack is a great place for those Raspberry Pi servers and home networking equipment, but it can also handle bigger jobs.

The basic system (or core) consists of three different parts: supports, connectors, and lock pins. The supports are the main structural bars, the connectors mostly go at the corners, and the lock pins ensure everything stays put. The nominal sizing is a 15 mm x 15 mm profile for the supports, with lengths being a multiple of 15 mm.

All is designed with 3D printing in mind, and requires no tools to assemble or disassemble. There are design elements we really appreciate, like how parts are printed at an angle, which improves strength while eliminating the need for supports. The lock pins (and the slots into which they go) are designed so that they are effective and will neither rattle nor fall out.

But the core system is just the foundation. There’s plenty of modularity and expansions to handle whatever one may need, from Gridfinity shelves and drawers to various faceplates and other modules. There are some example applications available from [KellerLab]’s HomeRacker models page, like CD shelf, under-desk drawer, or filament rack.

[KellerLab] welcomes any collaboration, so check out the GitHub repository for CAD references and design files.

One last point to make about the value of printing objects like this at an angle: not only can the resulting layer lines provide better strength and reduce or eliminate the need for supports, but printing at an angle can help hide layer lines.

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Ultrasonic Cutting On The Cheap

November 24, 2025 by Al Williams 15 Comments

When you think of ultrasonics, you probably think of a cleaner or maybe a toothbrush. If you are a Star Trek fan, maybe you think of knocking out crew members or showers. But there is another practical use of ultrasonics: cutting. By vibrating a blade at 40 kHz or so, you can get clean, precise cuts in a variety of materials. The problem? Commercial units are quite expensive. So [Electronoobs] decided to roll his own. Check it out in the video below.

There are dreams and then there’s reality. Originally, the plan was for a handheld unit, but this turned out not to be very practical. Coil actuators were too slow. Piezo elements made more sense, but to move the blade significantly, you need a larger element.

Taking apart an ultrasonic cleaner revealed a very large element, but mounting it to a small blade would be a problem. The next stop was an ultrasonic toothbrush. Inside was a dual piezo element with an interesting trick. The elements were mounted in a horn that acts like an ultrasonic megaphone, if you will.

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Fixing A Milltronics ML15 CNC Lathe Despite The Manufacturer’s Best Efforts

November 20, 2025 by Maya Posch 10 Comments

When you’re like [Wes] from Watch Wes Work fame, you don’t have a CNC machine hoarding issue, you just have a healthy interest in going down CNC machine repair rabbit holes. Such too was the case with a recently acquired 2001 Milltronics ML15 lathe, that at first glance appeared to be in pristine condition. Yet despite – or because of – living a cushy life at a college’s workshop, it had a number of serious issues, with a busted Z-axis drive board being the first to be tackled.

The Glentek servo board that caused so much grief. (Credit: Watch Wes Work, YouTube)

The identical servo control board next to it worked fine, so it had to be an issue on the board itself. A quick test showed that the H-bridge IGBTs had suffered the typical fate that IGBTs suffer, violently taking out another IC along with them. Enjoyably, this board by one Glentek Inc. did the rebranding thing of components like said IGBTs, which made tracking down suitable replacements an utter pain that was eased only by the desperate communications on forums which provided some clues. Of course, desoldering and testing one of the good IGBTs on the second board showed the exact type of IGBT to get.

After replacing said IGBTs, as well as an optocoupler and other bits and pieces, the servo board was good as new. Next, the CNC lathe also had a busted optical encoder, an unusable tool post and a number of other smaller and larger issues that required addressing. Along the way the term ‘pin-to-pin compatible’ for a replacement driver IC was also found to mean that you still have to read the full datasheet.

Of the whole ordeal, the Glentek servo board definitely caused the most trouble, with the manufacturer providing incomplete schematics, rebranding parts to make generic replacements very hard to find and overall just going for a design that’s interesting but hard to diagnose and fix. To help out anyone else who got cursed with a Glentek servo board like this, [Wes] has made the board files and related info available in a GitHub repository.

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Concrete Lathe Turns Metal

November 9, 2025 by Al Williams 43 Comments

Full disclosure. If you want a lathe capable of turning metal stock, you probably should just buy one. But what fun is that? You can do like [kachurovskiy] and build one with your 3D printer. If you are chuckling, thinking you can’t make 3D printed parts sturdy enough, you aren’t exactly wrong. [Kachurovskiy’s] trick is to 3D print forms and then cast the solid parts in concrete. The result looks great, and we don’t doubt his claim that it “can surpass many comparable lathes in rigidity and features.”

Even he admits that this is a “… hard, long, and expensive project…” But all good projects are. There’s a GitHub page with more details and informative videos below. The action shots are in the last video just before the six-minute mark. Around the seven-minute mark, you can see the machine cut a conical thread. Color us impressed!

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Magazine Transistor Tester Lives Again

October 27, 2025 by Al Williams 9 Comments

One of the lost pleasures of our modern world is the experience of going shopping at a grocery store, a mall, or a drugstore, and finding this month’s electronics magazine festooned with projects that you might like to build. Sure, you can find anything on the Internet, but there’s something to be said about the element of surprise. Can any of those old projects still be of interest?

[Bettina Neumryr] thinks so. She has a hobby of finding old magazine projects and building them. Her most recent installment is a transistor tester from the June 1983 issue of Everyday Electronics.

The tester was quite a neat job for 1983, with a neat case and a PC board. It measures beta and leakage. There’s an analog meter that can measure the collector current for a fixed base current (beta or hfe). Leakage is how much current flows between emitter and collector with the base turned off.

In 1983, we’d have loved to have a laser printer to do toner transfer for the PC board, but of course, that was unheard of in hobby circles of the day. The tester seemed to work right off the bat, although there was a small adjustment necessary to calibrate the device. All that was left was to put it in a period-appropriate box with some printed labels.

We loved the old electronics and computer magazines. Usually, when we see someone working on an old magazine project, it is probably not quite a literal copy of it. But either way is cool.

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They Don’t Make $37 Waveform Generators Like They Used To

October 14, 2025 by Al Williams 21 Comments

[CreativeLab] bought a cheap arbitrary waveform generator and noted that it only had a two-pin power cord. That has its ups and downs. We feel certain the intent was to isolate the internal switching power supply to prevent ground loops through the scope probes or the USB connector. However, it is nice to have all your equipment referencing the same ground. [CreativeLab] agrees, so he decided to do something about it.

Opening the box revealed that there was hardly anything inside. The main board was behind the front panel. There was also the power supply and a USB board. Plus lots of empty space. Some argue the case is made too large to be deceptive, but we prefer to think it was to give you a generous front panel to use. Maybe.

It was a simple matter to ground everything to a new three-pin connector, but that left the problem of the USB port. Luckily, since it was already out on its own board, it was easy to wire in an isolator.

Honestly? We’d have hesitated to do this unless we had made absolutely sure it didn’t pose some safety hazard to “jump over” the switching power supply. They are often isolated for some reason. However, the likelihood is that it is just fine. What do you think? Let us know in the comments.

A similar unit had a reverse engineering project featured on Hackaday many years ago. While these used to be exotic gear, if you don’t mind some limitations, it is very easy to roll your own these days.

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SMD Soldering With Big Iron

October 13, 2025 by Al Williams 32 Comments

You have some fine pitch soldering to do, but all you have on hand is a big soldering iron. What do you do? There are a few possible answers, but [Mr SolderFix] likes to pull a strand from a large wire, file the point down, and coil it around the soldering iron. This gives you a very tiny hot tip. Sure, the wire won’t last forever, but who cares? When it gives up, you can simply make another one.

Many people have done things like this before — we are guilty — but we really liked [Mr Solder Fix’s] presentation over two videos that you can see below. He coils his wire over a form. In his case, he’s using a screwdriver handle and some tape to get to the right size. We’ve been known to use the shanks of drill bits for that purpose, since it is easy to get different sizes.

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