Lego Monorail From Your 3D Printer

February 16, 2019 by Jenny List 5 Comments

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

February 10, 2019 by Richard Baguley 8 Comments

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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Hackaday Links: January 20, 2019

January 20, 2019 by Brian Benchoff 18 Comments

Let’s say you’re an infosec company, and you want some free press. How would you do that? The answer is Fortnite. Yes, this is how you hack Fortnite. This is how to hack Fortnite. The phrase ‘how to hack Fortnite’ is a very popular search term, and simply by including that phrase into the opening paragraph of this post guarantees more views. This is how you SEO.

Lasers kill cameras. Someone at CES visited the AEye booth, snapped a picture of an autonomous car at AEye’s booth, and the LIDAR killed the sensor. Every subsequent picture had a purple spot in the same place. While we know lasers can kill camera sensors, and this is a great example of that, this does open the door to a few questions: if autonomous cars have LIDAR and are covered in cameras, what’s going to happen to the cameras in an autonomous car driving beside another autonomous car? Has anyone ever seen more than one Cruise or Waymo car in the same place at the same time? As an aside, AEye’s company website’s URL is aeye.ai, nearly beating penisland.net (they sell pens on Pen Island) as the worst company URL ever.

This is something I’ve been saying for years, but now there’s finally a study backing me up. Lego is a viable investment strategy. An economist at Russia’s Higher School of Economics published a study, collecting the initial sale price of Lego sets from 1987 to 2015. These were then compared to sales of full sets on the secondary market. Returns were anywhere between 10 and 20% per year, which is crazy. Smaller sets (up to about 100 pieces) had higher returns than larger sets. This goes against my previous belief that a Hogwarts Castle, Saturn V, and UCS Falcon-heavy portfolio would outperform a portfolio made of cheap Lego sets. However, this observation could be tied to the fact that smaller sets included minifig-only packaging, and we all know the Lego minifig market is a completely different ball of wax. The Darth Revan minifig, sold as an exclusive for $3.99 just a few years ago, now fetches $35 on Bricklink. Further study is needed, specifically to separate the minifig market from the complete set market, but the evidence is coming in: Lego is a viable investment strategy, even when you include the 1-2% yearly cost of storing the sets.

Relativity Space got a launchpad. Relativity Space is an aerospace startup that’s building a rocket capable of lobbing my car into Low Earth Orbit with a methalox engine. They’re doing it with 3D printing. [Bryce Salmi], one of the hardware engineers at Relativity Space, recently gave a talk at the Hackaday Superconference about printing an entire rocket. The design is ambitious, but if there’s one device that’s perfectly suited for 3D printing, it’s a rocket engine. There are a lot of nonmachinable tubes going everywhere in those things.

Turning LEGO Blocks Into Music With OpenCV

December 30, 2018 by Donald Papp 2 Comments

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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ABS: Three Plastics In One

December 11, 2018 by Dan Maloney 31 Comments

It would be really hard to go through a typical day in the developed world without running across something made from ABS plastic. It’s literally all over the place, from toothbrush handles to refrigerator interiors to car dashboards to computer keyboards. Many houses are plumbed with pipes extruded from ABS, and it lives in rolls next to millions of 3D-printers, loved and hated by those who use and misuse it. And in the form of LEGO bricks, it lurks on carpets in the dark rooms of children around the world, ready to puncture the bare feet of their parents.

ABS is so ubiquitous that it makes sense to take a look at this material in terms of its chemistry and its properties. As we’ll see, ABS isn’t just a single plastic, but a mixture that takes the best properties of its components to create one of the most versatile plastics in the world.

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Lego Tardis Spins Through The Void

November 12, 2018 by Rich Hawkes 8 Comments

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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Sorting LEGO Is Like Making A Box Of Chocolates

September 27, 2018 by Steven Dufresne 6 Comments

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.

However, 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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