A man's hand is shown holding brass-colored tweezers. In the tweezers are held the inner race and the ball cage of a ball bearing, with half of the outer race lying below them on a table.

Splitting A Ball Bearing To Cut Out Backlash

August 11, 2026 by Aaron Beckendorf 9 Comments

Gears are usually the biggest contributors to backlash in a mechanical system, but they’re far from the only culprits. Ball bearings are a less obvious source of imprecision, since any gaps between the balls and the races can lead to axial wobble. Precision mechanisms can eliminate this by pairing two ball bearings, holding the outer races fixed, and applying a preload force to the inner traces. [Chronova Engineering], however, has a different solution, for which he split a ball bearing in half.

Besides taking up more room, thermal expansion also means that it’s difficult to apply a consistent preload force between two ball bearings. Instead, to make a self-contained preloaded bearing, [Chronova Engineering] first disassembled a single ball bearing. The most difficult part of this is taking apart the ball cage; the two parts of this are normally riveted together, but he managed to find a crimped cage and pry it apart. After taking the bearing completely apart, he cut the outer trace in half along the circumference, then reassembled the bearing. The split outer trace makes it possible to press the two halves together, preloading it and removing slop.

To see how well this worked, [Chronova Engineering] replaced the the ball bearing supporting one end of the feed screw for a milling machine with this new bearing. Before the replacement, it had a backlash of 0.1 to 0.2 millimeters; after the modification, it dropped to 30 to 40 microns. This kind of bearing is already known in the machining world – four-point-contact bearings use a very similar principle – but they don’t seem to be well known.

For more about these common yet remarkable rotary mechanisms, check out our article on bearings. If, on the other hard, precision isn’t a priority, you can always 3D print ball bearings.

CNC’d, CNC-inspired Adjustable Wrench Won’t Round Your Bolts

August 6, 2026 by Tyler August 40 Comments

We’ve probably all got one item in our toolboxes or chests that we really, really don’t like, but find too handy to toss. For [Someone Should Make That], that item was the bolt-rounding adjustable wrench. Rather than continuing to gripe about it, or alter his habits to make greater use of the full wrench set he also owns, he decided to build a better mousetrap. By mousetrap, we mean adjustable wrench.

It took a couple of iterations on-screen before he hits on a solution that seems to work quite well indeed. The problem [Someone] had with his adjustable wrench was one of physical slop: once adjusted, there’s just too much play in the mechanism, which results in rounded-off bolt heads. [Someone]’s CNC’d solution takes inspiration from the CNC machine that manufactures it: he’s using spring-loading in the adjustment screw akin to what you find in the anti-backlash nut on your CNC mill or 3D printer’s ball threads. The tension from the springs keeps the wrench tight to the bolt, and that keeps [Someone] from rounding them off. Speaking of 3D printers, he prototyped in plastic before machining, and the screw in the end product stayed that way. It would be interesting to see how well that holds up.

Not only do we appreciate that it’s solved a common problem many of us have, the ethos of “this angers me, so I shall hack it” is one we support 100%, so do give a watch unless you’re one of those people who absolutely can’t stand videos, even when they’re spring-loaded to have no slop. There’s some good tips for beginner CNC operators in there, too.

This isn’t the first time someone’s tried to reinvent this particular wheel, though the last version we liked was a ratchet.

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Tiny Moves, Big Depth: An Open-Source Macro Focus Slider

April 5, 2026 by Matt Varian 8 Comments

When taking macro photographs, you often need just a tiny bit of controlled motion — so little that it’s tough to pull off by hand. To address this, [Salveo] designed a small open-source macro photography slider featuring an anti-backlash handle.

Macro photography gives you an extremely shallow field of view, sometimes under 1 mm of depth, in which subjects stay in focus. To combat this, it’s common to capture multiple images while sliding the camera forward or backward, then combine them for a much larger depth of field than a single shot provides. [Salveo]’s slider gives fine control over this focus-stacking process, with the knob even marked to show every 1 mm of linear travel.

The slider is built around a 150 mm linear rail, though it could easily be lengthened or shortened to suit your needs. A T8 leadscrew, paired with anti-backlash nuts, translates the knob’s rotation into smooth linear motion. The knob itself uses a custom-designed anti-backlash mechanism to ensure the slider works cleanly in either direction.

You can grab all the 3D-printable files as well as the full bill of materials from the project page. Be sure to check out [Salveo]’s build video below. Thanks [Tim L.] for sending in this awesome open-source slider. Be sure to check out some of the other macro photography projects we’ve covered, too.

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Mostly Printed CNC Gets A Few Upgrades

May 7, 2024 by Dan Maloney 9 Comments

The Mostly Printed CNC is famous for two things. First, being made mostly from 3D printed parts and commonly available steel tubing. Second, because of the materials used, its rigidity isn’t fantastic. But any CNC router is better than no CNC router, and [Alan Reiner]’s “Mostly Mostly Printed CNC” upgrades the base MPCNC into a much more capable unit.

MPCNC purists may want to look away, as the video below shows [Alan] committing the heresy of adding linear rails to his machine. The rails were sourced from VEVOR and at less than $100 for 10 meters, it must have been hard to resist. The rigidity wasn’t amazing — witness the horrific chatter at around the 5:15 mark — but [Alan] sorted that out with some aluminum extrusion and printed adapters.

Those upgrades alone were enough to let [Alan] dive into some aluminum cutting, but he also wanted to address another gripe with his base build: the Z-axis backlash. The fix there was to add another lead screw nut on an adjustable carrier. By tweaking the relative angles of the two opposed nuts, almost all of the backlash was taken up. [Alan] also replaced the motor coupling on the Z axis with a Lovejoy-style coupler, to remove as much axial compliance as possible.

Along with the motion control mods, [Alan] improved work holding and added an enclosure to tame the chip beast, along with some upgrades to the control electronics. The results are pretty good and appear well worth the modest added expense. Maybe a wireless controller can be next on the upgrade list?

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Most AI Content Is Trash, Just Like Everything Else

November 3, 2023 by Donald Papp 31 Comments

[Max Woolf] has been working in the AI space since 2015, and among other work has created numerous useful open-source tools. He also recently wrote a thoughtful blog post that attempts to put into words his feelings on the state of things in the wake of experiencing a bit of an AI backlash-related burnout. Essentially, people effortlessly creating vast amounts of bad AI content has caused a bigger problem than we may realize.

How so? Well, Sturgeon’s law (summarized as “ninety percent of everything is crud”) applies to AI as much as it does to anything else. Theodore Sturgeon was a science fiction author and critic (and writer of multiple Star Trek episodes) who observed in the 1950s that while Science Fiction — the hot new popular thing at the time — was often derided by critics as being little more than low quality pap, so was everything else. It was true that most Science Fiction was garbage. But most work in other fields was of similarly low quality, and thus Science Fiction was really no different. It’s all trash, except for the parts one likes. Just like anything else.

What makes this observation particularly applicable to the current AI landscape is that, according to [Max], the incredible ease of use makes AI’s “ninety percent crud” very large indeed, and the attached backlash is similarly big. The remaining ten percent of AI that is absolutely fantastic and full of possibilities? It’s practically invisible due to how quickly the industry is moving, the speed with which the big players are vying to control it, and how unfashionable it has become to admit one is using AI tools at all.

[Max] knows the scene better than most. One of his projects is simpleaichat, a tool aimed not just at enabling people to integrate AI into projects easier, but piercing the hype around AI to more easily reveal just how these tools actually work. Sadly, a general AI backlash has made developing these tools feel rather less rewarding than it once did.

Ethics Whiplash As Sonos Tries Every Possible Wrong Way To Handle IoT Right

February 24, 2020 by Gerrit Coetzee 158 Comments

We’re trying to figure out whether Sonos was doing the right thing, and it’s getting to the point where we need pins, a corkboard, and string. Sonos had been increasing the functionality of its products and ran into a problem as they hit a technical wall. How would they keep the old speakers working with the new speakers? Their solution was completely bizarre to a lot of people.

First, none of the old speakers would receive updates anymore. Which is sad, but not unheard of. Next they mentioned that if you bought a new speaker and ran it on the same network as an old speaker, neither speaker would get updates. Which came off as a little hostile, punishing users for upgrading to newer products.

The final bit of weirdness was their solution for encouraging users to ditch their old products. They called it, “trading in for a 30% discount”, but it was something else entirely. If a user went into the system menu of an old device and selected to put it in “Recycle Mode” the discount would be activated on their account. Recycle Mode would then, within 30 days, brick the device. There was no way to cancel this, and once the device was bricked it wouldn’t come back. The user was then instructed to take the Sonos to a recycling center where it would be scrapped. Pictures soon began to surface of piles of bricked Sonos’s. There would be no chance to sell, repair, or otherwise keep alive what is still a fully functioning premium speaker system.

Why would a company do this to their customers and to themselves? Join me below for a guided tour of how the downsides of IoT ecosystem may have driven this choice.

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Robot Joints Go Modular With This Actuator Project

October 22, 2019 by Donald Papp 4 Comments

[John Lauer] has been hard at work re-thinking robot arms. His project to create modular, open source actuators that can be connected to one another to form an arm is inspiring, and boasts an impressively low parts cost as well. The actuators are each self-contained, with an ESP32 and a design that takes advantage of the form factors of inexpensive modules and parts from vendors like Aliexpress.

Flex spline in action, for reducing backlash

Each module has 3D printed gears (with an anti-backlash flex spline), an RGB LED for feedback, integrated homing, active cooling, a slip ring made from copper tape, and a touch sensor dial on the back for jogging and training input. The result is a low backlash, low cost actuator that keeps external wiring to an absolute minimum.

Originally inspired by a design named WE-R2.4, [John] has added his own twist in numerous ways, which are best summarized in the video embedded below. That video is number three in a series, and covers the most interesting developments and design changes while giving an excellent overview of the parts and operation (the video for part one is a basic overview and part two shows the prototyping process, during which [John] 3D printed the structural parts and gears and mills out a custom PCB.)

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