Bearing Witness: Measuring The Wobbles In Rotary Build

July 21, 2025 by Matt Varian 5 Comments

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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USB-C Rainbow Ranger: Sensing Volts With Style

July 15, 2025 by Matt Varian 1 Comment

USB-C has enabled a lot of great things, most notably removing the no less than three attempts to plug in the cable correctly, but gone are the days of just 5V over those lines. [Meticulous Technologies] sent in their project to help easily identify what voltage your USB-C line is running at, the USB VSense.

The USB VSense is an inline board that has USB-C connectors on either end, and supporting up to 240W you don’t have to worry about it throttling your device. One of the coolest design aspects of this board is that it uses stacked PCB construction as the enclosure, the display, and the PCB doing all the sensing and displaying. And for sensing this small device has a good number of cool tricks, it will sense all the eight common USB-C voltages, but it will also measure and alert you to variations of the voltage outside the normal range by blinking the various colored LEDs in specific patterns. For instance should you have it plugged into a line that’s sitting over 48V the VSense white 48V LED will be rapidly blinking, warning you that something in your setup has gone horribly wrong.

Having dedicated uniquely colored LEDs for each common level allows you to at a glance know what the voltage is at without the need to read anything. With a max current draw of less than 6mA you won’t feel bad about using it on a USB battery pack for many applications.

The USB VSense has completed a small production run and has stated their intention to open source their design as soon as possible after their Crowd Supply campaign. We’ve featured other USB-C PD projects and no doubt we’ll be seeing more as this standard continues to gain traction with more and more devices relying on it for their DC power.

From Leash To Locomotion: CARA The Robotic Dog

July 13, 2025 by Matt Varian 9 Comments

Normally when you hear the words “rope” and “dog” in the same sentence, you think about a dog on a leash, but in this robot dog, the rope is what makes it move, not what stops it from going too far. [Aaed Musa]’s latest project is CARA, a robotic dog made mostly of 3D printed parts, with brushless motors and ropes used to tie the motors and legs together.

In a previous post, we covered [Aaed Musa]’s use of rope as a mechanism to make capstan drives, enabling high torque and little to no backlash. Taking that gearbox design, tweaking it a bit, and using three motors, he was able to make a leg capable of moving in all three axes. He had to do a good deal of inverse kinematics math to get the leg moving around as desired; once he had the motion of a step defined, it was time to build the rest of the dog.

CARA is made primarily of 3D printed parts, with several carbon fiber tubes running its length for rigidity. The legs are all free to move not only forward and back but side to side some, as in a real dog. He uses 12 large brushless motors, as they provide the torque needed, and ODrive S1 motor controllers to control each one, controlled over CAN by a Teensy 4.1 microcontroller. There is also a small BNO086 IMU to sense CARA’s position relative to gravity, and a 24V cordless tool battery powers everything.

Once assembled, there was some more tuning of what type of motion CARA’s legs take while walking. There were a few tweaks to the printed parts to address some structural issues, and then a good deal more inverse kinematics math to make full use of the IMU, allowing CARA to handle inclines and make a much more natural movement style. [Aaed Musa] does a great job explaining his approach on his site as well as in the video below; we’re looking forward to seeing his future projects!

CARA isn’t alone on this site—be sure to check out the other robot dogs we’ve featured here.

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Wire Like A Pro: Peeking Into Wire Harness Mastery

July 12, 2025 by Matt Varian 26 Comments

There are many ways to learn, but few to none of them compare to that of spending time standing over the shoulder of a master of the craft. This awesome page sent in by [JohnU] is a fantastic corner of the internet that lets us all peek over that shoulder to see someone who’s not only spent decades learning the art of of creating cabl e harnesses, but has taken the time to distill some of that vast experience for the rest of us to benefit from.

This page is focused on custom automotive and motorcycle modifications, but it’s absolutely jam-packed with things applicable in so many areas. It points out how often automotive wiring is somewhat taken for granted, but it shouldn’t be; there are hundreds of lines, all of which need to work for your car to run in hot and cold, wet and dry. The reliability of wiring is crucial not just for your car, but much larger things such as the 530 km (330 mi) of wiring inside an Airbus A380 which, while a large plane, is still well under 100 m in length.

This page doesn’t just talk about cable harnessing in the abstract; in fact, the overwhelming majority of it revolves around the practical and applicable. There is a deep dive into wiring selection, tubing and sealing selection, epoxy to stop corrosion, and more. It touches on many of the most common connectors used in vehicles, as well as connectors not commonly used in the automotive industry but that possess many of the same qualities. There are some real hidden gems in the midst of the 20,000+ word compendium, such as thermocouple wiring and some budget environmental sealing options.

There is far more to making a thing beyond selecting the right parts; how it’s assembled and the tools used are just as important. This page touches on tooling, technique, and planning for a wire harness build-up. While there are some highly specialized tools identified, there are also things such as re-purposed knitting needles. Once a harness is fully assembled it’s not complete, as there is also a need for testing that must take place which is also touched on here.

Thanks to [JohnU] for sending in this incredible learning resource. If this has captured your attention like it has ours, be sure to check out some of the other wire harness tips we’ve featured!

Solder Smarts: Hands-Free Fume Extractor Hack

July 9, 2025 by Matt Varian 8 Comments

[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.

Budget Brilliance: DHO800 Function Generator

July 8, 2025 by Matt Varian 1 Comment

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: Cable Harness Design Tool

July 7, 2025 by Matt Varian 29 Comments

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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