Lego Monorail From Your 3D Printer

If you had to guess the age of a person hailing from a country in which Lego is commonly available, you might very well do it by asking them about the Lego trains available in their youth. Blue rails or grey rails, 4.5, 9, or 12 volt power, and even somewhat unexpectedly, one rail or two. If that last question surprises you we have to admit that we were also taken aback to discover that for a few years in the 1980s everybody’s favourite Danish plastic construction toy company produced a monorail system.

[Mike Rigsby] had a rather ambitious Christmas display to produce, and as part of it included a pair of reindeer, Rudolph and Bluedolph, atop freight cars on a loop of Lego monorail. He didn’t just use classic Lego parts off-the-shelf, instead he recreated the system in its entirety on his 3D printer; locomotive, rolling stock, and all. In a simlar way tot he original his locomotive sits between the two freight cars, each container housing a pair of AA batteries which together power the unit.

The Lego system isn’t perhaps a classic monorail, in that it involves a four-wheeled vehicle that is guided by a central rail rather than sitting upon it. Drive comes from teeth on the side of the rail which mesh with a gear on the power car. There have been 3D-printable sections of it available as add-ons for owners of classic sets for a while, but this may be the first printable locomotive and train. The Christmas novelty aspect of it all may be a little past its sell-by date here in February, but it’s still worth a look as a potential source of parts for any project that might require a linear rail system.

Perhaps surprisingly we’ve never featured a monorail before, though we have brought you a MagLev.

Make Your Lego Fly

We probably all used to make our Lego fly by throwing it across the room, but Flite Test have come up with a slightly more elegant solution: they converted a Lego quadcopter to fly. They did it by adding a  miniature flight controller, battery and motors/rotors to replace the Lego ones in the Lego City Arctic Air Transport kit. This combination flies surprisingly well, thanks to a thoughtful design that balances the heavier components inside the case.

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Turning LEGO Blocks into Music with OpenCV

We’re not sure what it is, but something about LEGO and music go together like milk and cookies when it comes to DIY musical projects. [Paul Wallace]’s Lego Music project is a sequencer that uses the colorful plastic pieces to build and control sound, but there’s a twist. The blocks aren’t snapped onto anything; the system is entirely visual. A computer running OpenCV uses a webcam to watch the arrangement of blocks, and overlays them onto a virtual grid where the positions of the pieces are used as inputs for the sequencer. The Y axis represents pitch, and the X axis represents time.

Embedded below are two videos. The first demonstrates how the music changes based on which blocks are placed, and where. The second is a view from the software’s perspective, and shows how the vision system processes the video by picking out the colored blocks, then using their positions to change different values which has an effect on the composition as a whole.

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Lego Tardis Spins Through the Void

Using LEGO Technic gears and rods seems like a great way of bringing animation to your regular LEGO creation. Using gears and crank shafts you can animate models from your favorite TV show or movie like LEGO kinetic sculpture maker, [Josh DaVid] has done when he created a spinning TARDIS.  Crank the handle and the sculpture spins through space and time.

The large gear stays in place. The hidden gears, turned by the crank, rotate a shaft from below that goes through the large gear making the TARDIS rotate around the main axis. Connected to the TARDIS model is a smaller gear, at an angle, that meshes with the larger, stationary, gear. This smaller gear is what causes the TARDIS to rotate around its own axis while the whole thing rotates around the main axis. If your hand gets too tired, you can substitute a LEGO motor.

It’s a neat effect, and you can get the plans [Josh]’s Etsy page. The best part, however, is that you can get a set with all the parts as well! The TARDIS is a popular item here and we’ve had plenty of projects with it as the focus: Everything from a tree topper to sub-woofers. The only question we have, of course, is, ‘Is it bigger on the inside?’

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Mini LEGO Technic Tank Patrols Your Desk Under ESP32 Control

We probably don’t have to tell the readers of Hackaday that LEGO isn’t just for kids; we’ve seen plenty of projects that live in an enclosure made of the multi-color bricks, and let’s not even get started on the Mindstorms builds we’ve seen over the years. But while LEGO (and especially the Technic product line) is fine for prototyping and putting together quick projects, the stock electronic components aren’t exactly top of the line. Which is why [Jason Kirsons] has been working on bridging the gap between LEGO and “real” parts.

His LEGO Technic tank is a perfect example of this principle. While the tank design itself is standard LEGO fare, he’s gone all in on the electronics. With an Adafruit Feather ESP32, custom motor controller board, and NEMA 8 steppers with 3D printed Technic adapters, this little tank has a lot more going on under the hood than you might expect. While this project is more a proof of concept than anything, the methods [Jason] demonstrates might be something to consider the next time you’re building with Billund’s best.

[Jason] chose the Feather ESP32 because of its small size, but you could get away with a generic board if you’re not trying to compress everything down into such a small footprint. Of course, if you go with another board you won’t be able to use the PCB he’s designed which attaches to the Feather and holds four Pololu DRV8835 motor drivers.

Easily the most broadly applicable element of this project is the work [Jason] has done designing adapter plates that let you use NEMA 8 motors with LEGO Technic parts. He’s put the adapters up on Thingiverse, for anyone looking for a drop-in solution to give their Technic creations a bit more oomph (technical term).

LEGO has a long history with hackers and makers. We’ve covered some absolutely incredible projects built with the famous construction set, and we don’t see any sign of it slowing down in the future.

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Sorting LEGO Is Like Making A Box Of Chocolates

Did you know that chocolate candy production and sorting LEGO bricks have something in common? They both use the same techniques for turning clumps of chocolates or bricks into individual ones moving down a conveyor belt. At least that’s what [Paco Garcia] found out when making his LEGO Sorter.

Sorting LEGO bricks using guidesHowever, he didn’t find that out right away. He first experimented with his own techniques, learning that if he fed bricks to his conveyor belt by dropping a batch of them in a line perpendicular to the direction of belt travel then no subsequent separation attempt of his worked. He then turned to [akiyuky’s] LEGO sorter for inspiration and dropped them onto the belt at an angle, ensuring that some bricks would be in front of others. A further trick he found is very well demonstrated in the chocolate sorting video below and shown in the image here. That is to use guides on the belt which serve to create speed differentials. Bricks move slower than the conveyor belt while pressed against a guide but when a brick leaves the guide, it accelerates to the speed of the conveyor belt, pulling away from the bricks still at the guide and thus separating them.

A further discovery had nothing to do with chocolate production, unless maybe for quality control. Once an individual brick had been separated out, it had to be classified. To do that he used Google’s Inception v3 neural network. But first, he had to retrain it for recognizing different types of LEGO bricks, something we’ve seen done before for use with recognizing playing cards. And to do the retraining, he needed many images of different bricks all separated into their different types. That’s where he came up with a clever trick. He used his own sorter for that. For example, to get a bunch of images of 1×1 bricks of different colors and orientations, he simply ran them through the sorter, saving the images to files and assigning them to the 1×1 brick class. He then used his desktop machine with a GeForce GT 730 GPU for the retraining, taking around 2.7 seconds per brick. For sorting though, he runs the trained neural network on a Raspberry Pi, taking 3.8 seconds for each brick. The resulting sorter works quite well, sorting with 89% accuracy. Watch it in action in the video below.
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FOSSCON 2018: Where Open Source and LEGO Collide

It probably won’t come as a surprise to anyone reading this, but hackers and makers absolutely love LEGO. We think you’d be hard pressed to find a Hackaday reader, young or old, that hasn’t spent some quality time with the little plastic bricks from Billund, Denmark. So it follows that there’s a considerable community of individuals who leverage their better than average technical prowess to utilize LEGO in new and unique ways. But the activities and history of these LEGO hackers is not exactly common knowledge to those who aren’t heavily vested in the hobby.

During the recent FOSSCON 2018 in Philadelphia, Daniel Pikora gave attendees a comprehensive look at the intersection of open source development and the world’s most popular brand of construction toys. A software developer with a penchant for open source code by trade, he’s also an avid member of what’s known as the Adult Fan of LEGO (AFOL) community who’s exhibited his creations at shows across the United States and Canada. Such a unique perspective, with a foot in both the FOSS and LEGO camps, makes Daniel an ideal tour guide for this particular microcosm of toys and tech.

In a whirlwind presentation that took attendees through 49 slides in about as many minutes, Daniel covered LEGO’s beginnings in the 1930s to the rise of 3D printed custom bricks, and everything in between. Some of the engineering-centric product lines, such as Technic and Mindstorms, were already fairly well known to the types of folk who spent a beautiful Saturday in Philadelphia at an open source conference. But Daniel’s deep-dive into the long history of open source LEGO projects brought to light the work of so many dedicated developers that everyone walked away with a newfound respect for the amount of work the AFOL community has put into elevating LEGO from a child’s toy to a legitimate tool. Join me below for a look at the particulars of that deep dive.

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