LEGO Monowheel Corners Like It’s On Rails

[Jason]’s at it again. This time the LEGO maestro is working on a LEGO BB-8 droid. As a first step he’s made a motorized monowheel that not only races along hallways and through living rooms at the peril of any passing people, but turns as well.

To drive it forward there’s an axle that runs across the center of the wheel and a motor that rotates that axle. He’s also included some weight bricks. Without the mass of those bricks for the rotation to work against, the motor and axle would just spin in place while the friction of the floor keeps the wheel from rotating. If you’ve seen the DIYer’s guide to making BB-8 drive systems, you’ll know that this is classified as an axle drive system.

LEGO monowheel interior shown while leaning to turn
LEGO monowheel interior shown while leaning to turn

For steering the monowheel left or right he has another mass located just above the axle. Shifting the mass to the left causes the monowheel to lean and move in that direction. Shifting the mass to the right makes the wheel move to the right in the same fashion. Being ever efficient, [Jason] has the motor that shifts the mass doubling as the mass itself.

As with any proof-of-concept, there are still some issues to work out. When turning the wheel left or right it can tip onto its side. Ridges on both sides of the wheel’s circumference reduce the chances of that happening but don’t eliminate it altogether. Also, the steering mass/motor doesn’t yet have a self-centering mechanism; after a turn it’s up to the person holding the remote control to find center. If the mass isn’t correctly centered after a turn, there tends to be some wobble.

As always, we’re looking forward to seeing how [Jason] solves those issues but first he’ll have to put it back together since, as you can see from the video below, it didn’t quite pass the stair test.

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Paper Tape Drive for a Live Performance Music Box

Music is a mystery to some of us. Sure, we know what we like when we hear it, but the idea of actually being able to make it baffles us. And the idea of being able to build new instruments to create it, like this paper-tape programmable music box (YouTube, embedded below), is beyond impressive.

You’ll no doubt remember [Martin Molin] of the group “Wintergatan” and his astounding marble madness music machine. This instrument is on a much more modest scale and is centered around an off-the-shelf paper tape music box. But the cheap plastic drive gears kept failing under performance conditions, so [Martin] headed to what appears to be his cave-based workshop and started grinding. He prototyped a new paper drive from Lego Technics, and while it worked, it needed help to pull the paper. What followed was an iterative design process that culminated in a hybrid of plastic and metal Technic parts that drive the paper reliably, and a musical instrument that’s much more than just a tinny wind-up music box. Hear it in action below with another new instrument, the Modulin, which sounds a little like a Theremin but looks like – ah, just watch the video.

The build video hints at more details to come, and we’re hoping for a complete series like that for the marble machine. We’d also love to see details on the Modulin too – if there ever was a hacked musical instrument, that’s it.

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Unary Clock for the Binary-Challenged

If binary clocks have you confused by all the math required to figure out what time it is, we have the solution for you: a unary clock. After all, what’s simpler than summing up powers of two? Powers of one! To figure out the time, you start with the ones digit. If it’s on, you add one to the total. Then move on to the next digit. Since 12 equals one, you add another one if it’s lit. Then on to the third LED. 13 = 1, so if it’s lit, you add another one, and so on.

OK, we’re messing around. Calling this a “unary” clock is ridiculous. When it’s seven o’clock, there are seven LEDs lit. Nice and easy to read. Sixty minute LEDs is silly, so here each minute LED stands for five minutes. Good enough.

What we really like about this clock is the build. It’s intended as educational for school kids, so it has to be simple to build and easy to personalize. Building the body out of Lego bricks fits the specs nicely. Transparent Lego bricks are used to give the white LEDs some color. That was too bright, so [Shrimping It] added paper cutouts from a hole punch as diffusers.

Clock builds are a great intro to electronics because they offer so many possibilities. Whether you want to go geary, use the clock as an excuse to try out fabrication techniques, or showcase a neat display technology, your imagination has a lot of room to wander. Show us yours?

Oh No! It’s the Claw!

What’s more seductive than a claw machine? After all, how hard can it be to snag that $2 teddy bear that is practically poking out of the pile of merchandise? But after 20 quarters, you realize you’ve spent $5, and you still don’t have anything to show for it.

[CreativeGuy88] decided to build his own claw machine (that way, he gets to keep the quarters). This sizable build is as much woodworking project as anything. However, the motors and control joysticks require electrical wiring and [CreativeGuy88] used Lego bricks to make much of the carriage.

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Lego Nuclear Reactor Uses Arduino

Before the NSA deletes this post, we’ll be clear: We’re talking about a model of a nuclear reactor, not the real thing. Using Legos, [wgurecky] built a point kinetic reactor model that interfaces with the reactor simulator, pyReactor.

Even without the Lego, the Python code demonstrates reactor control in several modes. In power control mode, the user sets a power output, and the reactor attempts to maintain it. In control rod mode, the user can adjust the position of the control rods and see the results.

If things get out of hand, there’s a SCRAM button to shut the reactor down in a hurry. The Lego model uses an Arduino to move the rods up and down (using a servo) and controls the simulated Cherenkov radiation (courtesy of blue LEDs).

We’ve been excited to see more high schools with significant engineering programs. This would be a good project for kids interested in nuclear engineering. It certainly is a lot safer than one of our previous reactor projects.

Rope Braiding Machine Built Entirely from LEGO Technics

If you’ve ever seen a rope-braiding machine in action, you know they’re amazing machines where bobbins of thread whirl and spin in a complex dance to weave the threads under and over each other. Building one of these machines must be incredibly difficult; building one out of LEGO Technics pieces is darn near insane.

[Nico71], as hardcore a Technics builder as they come, tackled this complex build and made it work. A large drum spins horizontally and carries three groups of three planetary-mounted thread bobbins. The entire drum spins in one direction while the bobbins and another die with three holes spin the other way. The resulting braids are then fed through another spinning die, and the resulting 9-strand rope is taken up by a winding drum. The drum has a self-reversing feeding mechanism to keep the finished spool neat and tidy. The most impressive thing about the build, though, is the fact that it’s all powered by a single motor, and that everything is synchronized via gears, shafts, sprockets, chains and clutches. It’s a Technics tour de force you can see in action after the break.

[Nico71]’s build are pretty amazing. Some are pure art, others are models of classic cars and motorcycles, but things like his loom and the calculator he’s working on now are remarkable. Of course if you need to see more of the mesmerizing ballet of rope-braiding machines, check out this 16-bobbin hand-cranked version.

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Lego Gaming Computer Case

Lego isn’t the first material that springs to mind when you think about building a new gaming computer case, but it does make sense when you think about it. It is easy to work with, can be easily reconfigured, and it’s pretty cheap. That’s the idea behind this very cool (no pun intended) gaming computer case build by [Mike Schropp]. Built around a Skylake i7 CPU and an NVidia 980 Ti graphics card, his build has an unusual X-shaped design that allows for plenty of airflow. The sides of the X hold the CPU cooler, the power supply, the hard drives and the graphics card cooler, so each of them has its own separate flow of cool air from the outside. That avoids the common problem of hot air from one component being passed over another, so it doesn’t get cooled properly. Critically for a gaming system, this design keeps all of the components much cooler than a more traditional case, which makes for more overclocking potential.

At the moment, [Mike] says he is struggling to keep up with the demand for people who want to buy custom versions of his build, but he is planning to release the details soon. “Initially that will probably be in the form of a DIY kit, where you can buy the plans with all the Lego bricks needed for the build, in a kit form” he told us. “Then you can add your own computer components to complete your build. At some point I’ll probably also just offer the plans themselves and allow the end-user to acquire the Lego bricks needed.”

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