Building An Interferometer With LEGO

February 28, 2025 by Lewin Day 14 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!

Gaze Upon This Omni-directional Treadmill’s Clever LEGO Construction

January 7, 2025 by Donald Papp 16 Comments

Want to see some wildly skillful LEGO construction? Check out [Banana Gear Studios]’ omni-directional treadmill which showcases not only how such a thing works, but demonstrates some pretty impressive problem solving in the process. Construction was far from straightforward!

A 9×9 grid of LEGO shafts all turning in unison is just one of the non-trivial design challenges.

In principle the treadmill works by placing an object on a bed of identical, rotating discs. By tilting the discs, one controls which edge is in contact with the object, which in turn controls the direction the object moves. While the concept is straightforward, the implementation is a wee bit more complex. LEGO pieces offer a rich variety of mechanical functions, but even so, making a 9×9 array of discs all rotate in unison turns out to be a nontrivial problem to solve. Gears alone are not the answer, because the shafts in such a dense array are a bit too close for LEGO gears to play nicely.

The solution? Break it down into 3×3 self-contained chunks, and build out vertically with gimbals to take up the slack for gearing. Use small elastic bands to transfer power between neighbors, then copy and paste the modular 3×3 design a few times to create the full 9×9 grid. After that it’s just a matter of providing a means of tilting the discs — which has its own challenges — and the build is complete.

Check out the video below to see the whole process, which is very nicely narrated and illustrates the design challenges beautifully. You may see some similarities to Disney’s own 360° treadmill, but as [Banana Gear Studios] points out, it is a technically different implementation and therefore not covered by Disney’s patent. In an ideal world no one would worry about getting sued by Disney over an educational LEGO project posted on YouTube, but perhaps one can’t be too careful.

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LDU Decoded: The Untold Tale Of LEGO Dimensions

December 27, 2024 by Heidi Ulrich 11 Comments

LEGO bricks might look simplistic, but did you know there’s an actual science behind their sizes? Enter LDUs — LEGO Draw Units — the minuscule measurement standard that allows those tiny interlocking pieces to fit together seamlessly. In a recent video [Brick Sculpt] breaks down this fascinating topic.

So, what is an LDU precisely? It’s the smallest incremental size used to define LEGO’s dimensions. For context, a standard LEGO brick is 20 LDUs wide, and a single plate is 8 LDUs tall. Intriguingly, through clever combinations of headlight bricks, jumper plates, and even rare Minifig neck brackets, builders can achieve offsets as tiny as 1 LDU! That’s the secret sauce behind those impossibly detailed LEGO creations.

We already knew that LEGO is far more than a toy, but this solidifies that theory. It’s a means of constructing for anyone with an open mind – on its own scale. The video below explains in detail how to achieve every dimension possible. If that inspires you to build anything, dive into these articles and see if you can build upon this discovery!

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3D Printing A Big LEGO Christmas Tree

December 20, 2024 by Lewin Day 8 Comments

LEGO make lots of neat floral arrangements these days, and even little Christmas trees, too. While they’re fun to build out of tiny little blocks, they’re a little small for use as your main Christmas tree. Sadly, a bigger version simply doesn’t exist in the LEGO catalog, so if that’s your desire, you’ll have to build your own—as [Ruth] and [Ellis] did!

The concept behind the build is as you’d expect. The duo effectively just 3D printed giant versions of LEGO pieces, with which they then assembled a large Christmas tree. It sounds very straightforward, but scaling an existing LEGO design up by six times tends to come with some complications. A tactical decision was made early on to ease proceedings—the original LEGO tree had a large brown base that would take lots of printing. This was eliminated in the hopes that it would speed the build significantly. The long plastic shafts that supported the original design were also replaced with steel shafts since printing them would have been incredibly difficult to do well.

The rest of the video demonstrates the huge amount of work that went into actually 3D printing and assembling this thing. It’s pretty great to watch, and you’ll learn a lot along the way.

We’ve seen other creators try similar projects, where they 3D print their own building blocks from scratch. It normally turns out much harder than expected! No surprise when you think about all the engineering that went into perfecting LEGO all those years ago.

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Do 3D Printers Dream Of LEGO Sheep?

December 9, 2024 by Heidi Ulrich 21 Comments

Imagine the power to clone your favorite LEGO piece—not just any piece, but let’s say, one that costs €50 second-hand. [Balazs] from RacingBrick posed this exact question: can a 3D scanner recreate LEGO pieces at home? Armed with Creality’s CR-Scan Otter, he set out to duplicate a humble DUPLO sheep and, of course, tackle the holy grail of LEGO collectibles: the rare LEGO goat.

The CR-Scan Otter is a neat gadget for hobbyists, capable of capturing objects as small as a LEGO piece. While the scanner proved adept with larger, blocky pieces, reflective LEGO plastic posed challenges, requiring multiple scans for detailed accuracy. With clever use of 3D printed tracking points, even the elusive goat came to life—albeit with imperfections. The process highlighted both the potential and the limitations of replicating tiny, complex shapes. From multi-colored DUPLO sheep to metallic green dinosaur jaws, [Balazs]’s experiments show how scanners can fuel customization for non-commercial purposes.

For those itching to enhance or replace their builds, this project is inspiring but practical advice remains: cloning LEGO pieces with a scanner is fun but far from plug-and-play. Check out [Balazs]’s exploration below for the full geeky details and inspiration.

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A variety of LEGO and the damage they've done to cardboard.

Stepping On LEGO For Science

November 20, 2024 by Kristina Panos 34 Comments

You might say that the worst LEGO to step on is any given piece that happens to get caught underfoot, but have you ever thought about what the worst one would really be? For us, those little caltrops come to mind most immediately, and we’d probably be satisfied with believing that was the answer. But not [Nate Scovill]. He had to quantitatively find out one way or another.

And no, the research did not involve stepping on one of each of the thousands of LEGO pieces in existence. [Nate] started by building a test rig that approximated the force of his own 150 lb. frame stepping on each piece under scrutiny and seeing what it did to a cardboard substrate.

And how did [Nate] narrow down which pieces to try? He took to the proverbial streets and asked redditors and Discordians to help him come up with a list of subjects.

If you love LEGO to the point where you can’t bear to see it destroyed, then this video is not for you. But if you need to know the semi-scientific answer as badly as we did, then go for it. The best part is round two, when [Nate] makes a foot out of ballistics gel to rate the worst from the first test. So, what’s the worst LEGO to step on? The answer may surprise you.

And what’s more dangerous than plain LEGO? A LEGO Snake, we reckon.

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Hackaday Podcast Episode 292: Stainless Steel Benchies, Lego Turing Machines, And A Digital Camera Made Of Pure DIY

October 11, 2024 by Dan Maloney No comments

Here we are in October, improbably enough, and while the leaves start to fall as the goblins begin to gather, Elliot and Dan took a break from the madness to talk about all the wonderful hacks that graced our pages this week. If there was a theme this week, it was long-term projects, like the multiple years one hacker spent going down dead ends in the quest for DIY metal 3D printing. Not to be outdone, another hacker spent seven years building a mirrorless digital camera that looks like a commercial product. And getting a solderless PCB to do the blinkenlight thing took a long time too.

Looking to eliminate stringing in your 3D prints? Then you’ll want to avoid the “pause and attach” approach, which intentionally creates strings in your prints. Wondering if you can 3D print bearings? You can, but you probably shouldn’t unless you have a particular use in mind. And what happens when you have an infinitely large supply of Lego? Why, you build a Turing machine on steroids, of course.

Finally, we take a look at this week’s “Can’t-Miss” articles with a look into plastic recycling and why we can’t have nice things yet, and we take a trip out into orbit and examine the ins and outs of Lagrange points.

And a little mea culpa from the editing desk: Sorry the podcast is coming out late this week. Audacity ate my files. If you’re ever in a similar circumstance, you can probably halfway save your bacon with audacity-project-tools. Ask me how I know.