There Are Better Lego-Compatible Universal Joints Out There

July 1, 2025 by 11 Comments

Lego’s Technic line features all kinds of mechanical devices, from cogs to gears to chains and even pneumatic components. However, the vast majority of these components are made out of plastic and are only capable of toy-like levels of performance. In the competitive world of Lego YouTube, builders often push these parts to their limits, breaking them more often than you might think. To that end, [Brick Experiment Channel] has been investigating stouter Lego-compatible universal joints from a variety of third-party manufacturers.

The video starts with a simple demonstration, showing that a Lego universal joint pops apart at just 0.4 Nm of torque. It’s no surprise, given it relies on tiny plastic pins in snap-fit joints. However, this means that it’s not that hard to build a stronger universal joint to outperform the stock parts.

The video steps through a range of other options available on the market. For example, CaDA builds a universal joint using aluminium sleeves, a copper center, and steel pins to join everything together. It’s so strong that the plastic Lego axles fail long before the joint does. Tested with third-party aluminum axles, it eventually fails at 2.3 Nm of torque when the aluminum sleeve snaps. An all-steel joint from MTP goes even harder, eventually stripping out its axle mount at 4 Nm. The rest of the video goes on to explore angular performance, size, and other design features.

It’s fair to say that if you’re swapping out universal joints and axles for aluminum steel parts, you’re not really playing with Lego anymore. At the same time, it’s neat that there exists a sort of defacto standard kit for mechanical experimentation that is now being expanded upon with stronger components. Video after the break.

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Mechanical 7-Segment Display Combines Servos And Lego

June 25, 2025 by 4 Comments

If you need a seven-segment display for a project, you could just grab some LED units off the shelf. Or you could build something big and electromechanical out of Lego. That’s precisely what [upir] did, with attractive results.

The build relies on Lego Technic parts, with numbers displayed by pushing small black axles through a large yellow faceplate. This creates a clear and easy to read display thanks to the high contrast. Each segment is made up of seven axles that move as a single unit, driven by a gear rack to extend and retract as needed. By extending and retracting the various segments in turn, it’s possible to display all the usual figures you’d expect of a seven-segment design.

It’s worth noting, though, that not everything in this build is Lego. The motors that drive the segments back and forth are third-party components. They’re Geekservo motors, which basically act as Lego-mountable servos you can drive with the electronics of your choice. They’re paired with an eight-channel servo driver board which controls each segment individually. Ideally, though, we’d see this display paired with a microcontroller for more flexibility. [upir] leaves that as an exercise for the viewer for now, with future plans to drive it with an Arduino Uno.

Design files are on Github for the curious. We’ve featured some similar work before, too, because you really can build anything out of Lego. Video after the break.

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A Lego vehicle crossing a gap between two benches.

Making A LEGO Vehicle Which Can Cross Large Gaps

June 3, 2025 by 6 Comments

Here is a hacker showing off their engineering chops. This video shows successive design iterations for a LEGO vehicle which can cross increasingly large gaps.

At the time of writing this video from [Brick Experiment Channel] has been seen more than 110,000,000 times, which is… rather a lot. We guess with a view count like that there is a fairly good chance that many of our readers have already seen this video, but this is the sort of video one could happily watch twice.

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Reverse Engineering LEGO Island

May 24, 2025 by 4 Comments

While LEGO themed video games have become something of a staple, in 1997 they were something of an odity. LEGO Island became the first LEGO video game released outside of Japan in 1997 and become something of a hit with over one million copies sold. The game was beloved among fans and set the stage for more LEGO video games to come. In an effort of love, [MattKC] put together a team to reverse engineer the game.

The team set out with the intent to create a near perfect recreation of the codebase, relying on custom made tools to run byte checks on the rewrite compilation and the original binary. While the project is functionally complete, [MattKC] believes it is impossible to get a byte accurate codebase. This is because of what the team called “compiler entropy.” Strange behaviors exists inside of Microsoft’s Visual C++ compiler of the era, and small changes in the code have seemingly random effects to unrelated parts of the binary. To mitigate this issue would likely require either partially reverse engineering Visual C++ or brute forcing the code, both of which would take a large amount of effort and time for no real benefit.

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Welcome Your New AI (LEGO) Overlord

May 15, 2025 by 13 Comments

You’d think a paper from a science team from Carnegie Mellon would be short on fun. But the team behind LegoGPT would prove you wrong. The system allows you to enter prompt text and produce physically stable LEGO models. They’ve done more than just a paper. You can find a GitHub repo and a running demo, too.

The authors note that the automated generation of 3D shapes has been done. However, incorporating real physics constraints and planning the resulting shape in LEGO-sized chunks is the real topic of interest. The actual project is a set of training data that can transform text to shapes. The real work is done using one of the LLaMA models. The training involved converting Lego designs into tokens, just like a chatbot converts words into tokens.

There are a lot of parts involved in the creation of the designs. They convert meshes to LEGO in one step using 1×1, 1×2, 1×4, 1×6, 1×8, 2×2, 2×4, and 2×6 bricks. Then they evaluate the stability of the design. Finally, they render an image and ask GPT-4o to produce captions to go with the image.

The most interesting example is when they feed robot arms the designs and let them make the resulting design. From text to LEGO with no human intervention! Sounds like something from a bad movie.

We wonder if they added the more advanced LEGO sets, if we could ask for our own Turing machine?

Levitating Lego Generator Runs On Air

March 31, 2025 by 4 Comments

[Jamie] decided to build a generator, and Lego is his medium of choice. Thus was created a fancy levitating generator that turns a stream of air into electricity. 

The basic concept is simple enough for a generator—magnets moving past coils to generate electricity. Of course, Lego doesn’t offer high-strength magnetic components or copper coils, so this generator is a hybrid build which includes a lot of [Jamie’s] non-Lego parts. Ultimately though, this is fun because of the weird way it’s built. Lego Technic parts make a very crude turbine, but it does the job. The levitation is a particularly nice touch—the build uses magnets to hover the rotor in mid-air to minimize friction to the point where it can free wheel for minutes once run up to speed. The source of power for this contraption is interesting, too. [Jamie] didn’t just go with an air compressor or a simple homebrew soda bottle tank. Instead, he decided to use a couple of gas duster cans to do the job. The demos are pretty fun, with [Jamie] using lots of LEDs and a radio to demonstrate the output.  The one thing we’d like to see more of is proper current/voltage instrumentation—and some measurement of the RPM of this thing!

While few of us will be rushing out to build Lego generators, the video nonetheless has educational value from a mechanical engineering standpoint. Fluids and gases really do make wonderful bearings, as we’ve discussed before. Video after the break.

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Building An Interferometer With LEGO

February 28, 2025 by 13 Comments

LEGO! It’s a fun toy that is popular around the world. What you may not realize is that it’s also made to incredibly high standards. As it turns out, the humble building blocks are good enough to build a interferometer if you’re so inclined to want one. [Kyra Cole] shows us how it’s done.

The build in question is a Michelson interferometer; [Kyra] was inspired to build it based on earlier work by the myphotonics project. She was able to assemble holders for mirrors and a laser, as well as a mount for a beamsplitter, and then put it all together on a LEGO baseboard. While some non-LEGO rubber bands were used in some areas, ultimately, adjustment was performed with LEGO Technic gears.

Not only was the LEGO interferometer able to generate a proper interference pattern, [Kyra] then went one step further. A Raspberry Pi was rigged up with a camera and some code to analyze the interference patterns automatically. [Kyra] notes that using genuine bricks was key to her success. Their high level of dimensional accuracy made it much easier to achieve her end goal. Sloppily-built knock-off bricks may have made the build much more frustrating to complete.

We don’t feature a ton of interferometer hacks around these parts. However, if you’re a big physics head, you might enjoy our 2021 article on the LIGO observatory. If you’re cooking up your own physics experiments at home, don’t hesitate to drop us a line!

Thanks to [Peter Quinn] for the tip!