3D printed rotary table

Bearing Witness: Measuring The Wobbles In Rotary Build

3D printing has simplified the creation of many things, but part of making something is knowing just how much you can rely on it. On the [BubsBuilds] YouTube channel, he built a cheap rotary table and then walked through the process of measuring the error inherent in any rotating system.

Starting with a commercial rotary table, [BubsBuilds] decided he wanted a rotary stage that was both lighter and had provisions for motorized movement. Most of the rotary build is 3D printed, with the large housing and table made from PETG, and the geared hub and worm gear printed on a resin printer. The bearings used to support the worm gear are common skateboard bearings. There is also a commercial thrust bearing and 49 larger 9.5 mm ball bearings supporting the rotating tabletop.

There are three different types of runout to be measured on a rotating stage: axial, radial, and angular. Axial runout is fairly straightforward to discern by measuring the vertical variation of the table as it rotates. Radial runout measures how true the rotation is around the center of the table. Angular runout measures how level the table stays throughout its range. Since these two runouts are tied to each other, [BubsBuilds] showed how you can take measurements at two different heights and use trigonometry to obtain both your radial and angular runout

This is a great walk-through of how to approach measuring and characterizing a system that has multiple variables at play. Be sure to check out some of the other cool rotary tables we’ve featured.

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The Open-Source Multimeter: The HydraMeter

Designing An Open Source Multimeter: The HydraMeter

Our hacker [John Duffy] wrote in to let us know about a video he put together to explain the design of his open-source multimeter, the HydraMeter.

If you’re interested in how the circuitry for a voltmeter, ohmmeter, or ammeter might work, this video is a masterclass. In this long and detailed video, [John] walks us through his solutions to various challenges he had while designing his own multimeter. We covered this multimeter last year, and this new video elaborates on the design of the HydraMeter which has been a work in progress for years now.

The basic design feeds voltage, current, and resistance front-ends into an Analog to Digital Converter (ADC), which then feeds into a microcontroller and out to the (detachable) display. You can find the KiCad design files on the GitHub page. There is also a write-up on hackaday.io.

The user interface for the meter is… opinionated, and perhaps not to everyone’s taste. In the video, [John] talks a little bit about why he made the UI work the way that it does, and he noted that adding a rotary range switch is a goal for version 2.0.

Thank you, [John], for putting this video together; it is an excellent resource. We look forward to seeing version 2.0 develop soon!

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2025 One-Hertz Challenge: HP Logic Probe Brought Into The Future

[Robert Morrison] had an ancient HP 545A logic probe, which was great for debugging SMT projects. The only problem was that being 45 years old, it wasn’t quite up to scratch when it came to debugging today’s faster circuitry. Thus, he hacked it to do better, and entered it in our 2025 One Hertz Challenge to boot!

[Robert’s] hack relied on the classic logic probe for its stout build and form factor, which is still useful even on today’s smaller hardware. Where it was lacking was in dealing with circuits running at 100 MHz and above. To rectify this, [Robert] gave the probe a brain transplant with a Sparkfun Alorium FPGA board and a small display. The FPGA is programmed to count pulses while measuring pulse widths and time, and it then drives the display to show this data to the user. There’s also a UART output, and [Robert] is actively developing further logic analyzer features, too.

You might be questioning how this project fits in the One Hertz Challenge, given it’s specifically built for running at quite high speeds. [Robert] snuck it in under the line because it resamples and updates the display on a once-a-second basis. Remember, as per the challenge site—”For this challenge, we want you to design a device where something happens once per second.” We’re giving you a lot of leeway here!

Often, old scopes and probes and other gear are really well built. Sometimes, it’s worth taking the best of the old physical hardware and combining it with modern upgrades to make something stout that’s still useful today. Meanwhile, if you’re cooking up your own neo-retro-logic probes, don’t hesitate to notify the tipsline!

Die Cut Machine Makes Portable Metal Cuts

[Kevin Cheung] likes to upcycle old soda cans into — well — things. The metal is thin enough to cut by hand, but he’d started using a manual die-cutting machine, and it worked well. The problem? The machine was big and heavy, weighing well over 30 pounds. The solution was to get a lightweight die cutter. It worked better than expected, but [Kevin] really wanted it to be more portable, so he stripped it down and built the mechanism into a new case.

The video below isn’t quite a “how-to” video, but if you like watching someone handcraft something with a lot of skill, you’ll enjoy it. It also might give you ideas about how you could use one of these cutters, even if you don’t bother building a nice case for it.

We’ve seen cutters that use computer control, but they aren’t inexpensive. They will, however, make the same kind of cuts. But these manual die cutters are very inexpensive, and you simply have to find a way to make the die. You can easily make them for cutting paper, and, with the right materials, you can make the kind you see in [Kevin]’s video, too.

We have to admit, carrying the gizmo into a public place seemed to make a lot of people happy. So maybe portability is a good goal. But either way, you can have some fun with a machine like that.

If you want to cut paper, these work great. If you want paper to make the cuts, we have just the thing for you.

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fume extractor

Solder Smarts: Hands-Free Fume Extractor Hack

[Ryan] purchased a large fume extractor designed to sit on the floor below the work area and pull solder fumes down into its filtering elements. The only drawback to this new filter was that its controls were located near his feet. Rather than kicking at his new equipment, he devised a way to automate it.

By adding a Wemos D1 Mini microcontroller running ESPHome, a relay board, and a small AC-to-DC transformer, [Ryan] can now control the single push button used to cycle through speed settings wirelessly. Including the small transformer inside was a clever touch, as it allows the unit to require only a single power cable while keeping all the newfound smarts hidden inside.

The relay controls the button in parallel, so the physical button still works. Now that the extractor is integrated with Home Assistant, he can automate it. The fan can be controlled via his phone, but even better, he automated it to turn on by monitoring the power draw on the smart outlet his soldering iron is plugged into. When he turns on his iron, the fume extractor automatically kicks in.

Check out some other great automations we’ve featured that take over mundane tasks.

DHO800 function generator

Budget Brilliance: DHO800 Function Generator

The Rigol oscilloscopes have a long history of modifications and hacks, and this latest from [Matthias] is an impressive addition; he’s been working on adding a function generator to the DHO800 line of scopes.

The DHO800 series offers many great features: it’s highly portable with a large 7-inch touchscreen, powered by USB-C, and includes plenty of other goodies. However, there’s room for enhancements. [Matthias] realized that while software mods exist to increase bandwidth or unlock logic analyzer functions, the hardware needed to implement the function generator—available in the more expensive DHO900 series—was missing.

To address this, he designed a daughterboard to serve as the function generator hardware, enabling features that software tweaks can unlock. His goal was to create an affordable, easy-to-produce, and easy-to-assemble interface board that fits in the space reserved for the official daughterboard in higher-end scopes.

Once the board is installed and the software is updated, the new functionality becomes available. [Matthias] clearly explains some limitations of his implementation. However, these shortcomings are outweighed by the tremendous value this mod provides. A 4-channel, 200 MHz oscilloscope with function generator capabilities for under $500 is a significant achievement. We love seeing these Rigol mods enhance tool functionality. Thanks, [Matthias], for sharing this project—great job bringing even more features to this popular scope.

splice-cad assembly

Splice CAD: Cable Harness Design Tool

Cable harness design is a critical yet often overlooked aspect of electronics design, just as essential as PCB design. While numerous software options exist for PCB design, cable harness design tools are far less common, making innovative solutions like Splice CAD particularly exciting. We’re excited to share this new tool submitted by Splice CAD.

Splice CAD is a browser-based tool for designing cable assemblies. It allows users to create custom connectors and cables while providing access to a growing library of predefined components. The intuitive node editor enables users to drag and connect connector pins to cable wires and other pinned connectors. Those familiar with wire harnesses know the complexity of capturing all necessary details, so having a tool that consolidates these properties is incredibly powerful.

Among the wire harness tools we’ve featured, Splice CAD stands out as the most feature-rich to date. Users can define custom connectors with minimal details, such as the number of pins, or include comprehensive information like photos and datasheets. Additionally, by entering a manufacturer’s part number, the tool automatically retrieves relevant data from various distributor websites. The cable definition tool is equally robust, enabling users to specify even the most obscure cables.

Once connectors, cables, and connections are defined, users can export their designs in multiple formats, including SVG or PDF for layouts, and CSV for a detailed bill of materials. Designs can also be shared via a read-only link on the Splice CAD website, allowing others to view the harness and its associated details. For those unsure if the tool meets their needs, Splice CAD offers full functionality without requiring an account, though signing in (which is free) is necessary to save or export designs. The tool also includes a version control system, ideal for tracking design changes over time. Explore our other cable harness articles for more tips and tricks on building intricate wire assemblies.

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