There Are Better Lego-Compatible Universal Joints Out There

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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BeyBlades Made Ever More Dangerous With 3D Printing

If you’re unfamiliar with Beyblades, they’re a simple toy. They consist of spinning tops, which are designed to “fight” in arenas by knocking each other around. While the off-the-shelf models are deemed safe enough for children to play with, [Jon Bringus] decided to take the danger level up a few notches with some custom launchers of his own design.

[Jon]’s project started with some of the early metal Beyblades, which are traditionally launched with a small geared ripcord device. He soon realized he could up the action by doing one simple thing—spinning the tops far faster than the manufacturer ever intended. More rotational speed equals more kinetic energy equals more legal liability fun, or so the equation goes.

The design for [Jon’s] “WMD Launcher” is straightforward enough—he combined a lawnmower pull starter with a 12:1 geartrain to turn the Beyblades at truly ludicrous speeds. It’s basic engineering — a couple of 3D-printed gears do the job — but the results are hilarious. The tops begin to emit loud noises as they turn in combat, and some move so fast and erratically that they won’t even stay inside the arena. Protective eyewear is virtually mandatory. Files are on Printables for those eager to build one at home.

Yes, ruining a game of Beyblades is as simple as building an irresponsibly fast launcher. You needn’t even use some fancy brushless motor to hurt yourself — just a little gearing is enough to cause havoc. We’ve featured similar work on this topic before, too. Video after the break.

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Behold A Geared, Continuously Variable Transmission

When it comes to transmissions, a geared continuously-variable transmission (CVT) is a bit of a holy grail. CVTs allow smooth on-the-fly adjustment of gear ratios to maintain a target speed or power requirement, but sacrifice transmission efficiency in the process. Geared transmissions are more efficient, but shift gear ratios only in discrete steps. A geared CVT would hit all the bases, but most CVTs are belt drives. What would a geared one even look like? No need to wonder, you can see one for yourself. Don’t miss the two videos embedded below the page break.

The outer ring is the input, the inner ring is the output, and the three little gears with dots take turns transferring power.

The design is called the RatioZero and it’s reminiscent of a planetary gearbox, but with some changes. Here’s how the most visible part works: the outer ring is the input and the inner ring is the output. The three small gears inside the inner ring work a bit like relay runners in that each one takes a turn transferring power before “handing off” to the next. The end result is a smooth, stepless adjustment of gear ratios with the best of both worlds. Toothed gears maximize transmission efficiency while the continuously-variable gear ratio allows maximizing engine efficiency.

There are plenty of animations of how the system works but we think the clearest demonstration comes from [driving 4 answers] with a video of a prototype, which is embedded below. It’s a great video, and the demo begins at 8:54 if you want to skip straight to that part.

One may think of motors and gearboxes are a solved problem since they have been around for so long, but the opportunities to improve are ongoing and numerous. Even EV motors have a lot of room for improvement, chief among them being breaking up with rare earth elements while maintaining performance and efficiency.

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A milling machine with an attached pantograph following the various intricate patterns of a spirograph on the bench next to it. The spirograph is a series of acrylic gears and brass connecting bars mounted on a wooden base.

Taking A Spirograph Mill For A Spin

Spirographs can make some pretty groovy designs on paper, but what if you want to take it a step further? [Uri Tuchman] has used the pantograph on his milling machine to duplicate the effect in harder materials.

[Tuchman] starts with a quick proof-of-concept using an actual plastic Spirograph toy to make sure it isn’t a totally unworkable idea. Unsurprisingly, the plastic is too flexible to give a highly detailed result on the MDF test piece, so he laser cut an acrylic version as the next prototype. This provided much better stiffness, but he needed to adjust gear ratios and ergonomics to make the device more usable.

The final iteration uses a combination of laser cut acrylic and machined brass components to increase rigidity where needed. A hand-turned knob for the crank adds a classy touch, as does the “Spiromatic 2000” brass plate affixed to the wooden base of the mechanism.

This isn’t the first spirograph-related project we’ve seen. How about one made of LEGO Mindstorms, another using Arduino, or one that makes these patterns on your oscilloscope?

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Studying The Finer Points Of 3D Printed Gears

[How to Mechatronics] on YouTube endeavored to create a comprehensive guide comparing the various factors that affect the performance of 3D printed gears. Given the numerous variables involved, this is a challenging task, but it aims to shed light on the differences. The guide focuses on three types of gears: the spur gear with straight teeth parallel to the gear axis, the helical gear with teeth at an angle, and the herringbone gear, which combines two helical gear designs. Furthermore, the guide delves into how printing factors such as infill density impact strength, and it tests various materials, including PLA, carbon fiber PLA, ABS, PETG, ASA, and nylon, to determine the best options.

The spur gear is highly efficient due to the minimal contact path when the gears are engaged. However, the sudden contact mechanism, as the teeth engage, creates a high impulse load, which can negatively affect durability and increase noise. On the other hand, helical gears have a more gradual engagement, resulting in reduced noise and smoother operation. This leads to an increased load-carrying capacity, thus improving durability and lifespan.

It’s worth noting that multiple teeth are involved in power transmission, with the gradual engagement and disengagement of the tooth being spread out over more teeth than the spur design. The downside is that there is a significant sideways force due to the inclined angle of the teeth, which must be considered in the enclosing structure and may require an additional bearing surface to handle it. Herringbone gears solve this problem by using two helical gears thrusting in opposite directions, cancelling out the force.

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Clipper Windpower: Solutions In Search Of Problems

The first modern wind turbines designed for bulk electricity generation came online gradually throughout the 80s and early 90s. By today’s standards these turbines are barely recognizable. They were small, had low power ratings often in the range of tens to hundreds of kilowatts, and had tiny blades that had to rotate extremely quickly.

When comparing one of these tiny machines next to a modern turbine with a power rating of 10 or more megawatts with blades with lengths on the order of a hundred meters, one might wonder if there is anything in common at all. In fact, plenty of turbines across the decades share fundamental similarities including a three-blade design, a fairly simple gearbox, and a single electric generator. While more modern turbines are increasingly using direct-drive systems that eliminate the need for a gearbox and the maintenance associated with them, in the early 2000s an American wind turbine manufacturer named Clipper Windpower went in the opposite direction, manufacturing wind turbines with an elaborate, expensive, and heavy gearbox that supported four generators in each turbine. This ended up sealing the company’s fate only a few years after the turbines were delivered to wind farms.

Some history: the largest terrestrial wind turbines were approaching the neighborhood of 2 megawatts, but some manufacturers were getting to these milestones essentially by slapping on larger blades and generators to existing designs rather than re-designing their turbines from the ground up to host these larger components. This was leading to diminishing returns, as well as an increased amount of mechanical issues in the turbines themselves, and it was only a matter of time before the existing designs wouldn’t support this trend further. Besides increased weight and other mechanical stresses on the structure itself, another major concern was finding (and paying for) cranes with enough capacity to hoist these larger components to ever-increasing heights, especially in the remote locations that wind farms are typically located. And cranes aren’t needed just for construction; they are also used whenever a large component like a generator or blade needs to be repaired or replaced. Continue reading “Clipper Windpower: Solutions In Search Of Problems”

It’s Easy To Make Gears Out Of Wood

Typically, most of the gears we use in our life are made of plastic or metal. However, wood gears can do just fine in some simple roles, and they’re utterly pleasant to make, as this video from [botto bie] demonstrates.

With steady hands, it’s easy to make basic gears by hand with basic tools and a printer. You just need the help of a spur gear generator to produce the required outlines for you to follow. [botto bie] uses the online tool from Evolvent Design which will spit out DXF or SVG files as you desire.

Basic woodworking techniques are used to produce the gears, and they prove simple and effective. A rack is produced by first applying a involute tooth template with paper to a rectangular piece of wood. A series of circular and table jigsaw operations are then used to cut out the required material to produce the rack. A variety of toothed gears are produced in a similar fashion.

If you’re lacking a CNC machine or a 3D printer, this can be a great way to experiment. Bonus points if you use your wooden geartrain as part of some kind of exciting mechanism, like an automated marble run or musical contraption. Video after the break.

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