Parent To The Power Wheels Rescue

If the [realjohnnybravo] is the one from the show, it appears he finally managed to get a girlfriend, marry her, and produce at least one son. As the old schoolyard rhyme goes, first comes love, then comes marriage, then comes filling the whole *!$&# backyard with brightly colored plastic garbage. One of these items, a Power Wheels quad bike,  suffered a blow from planned obsolescence leaving behind a traumatized child. [realjohnnybravo] decided to fix it.

He made frequent mention of how one could go to a store and purchase replacement gears for the toy. Perhaps it’s a German thing. Regardless, he shows experience with internet comments by justifying his adventure in gear manufacturing with, paraphrased, “I’m having fun and learning so back off you pedantic jerks.”

Resin casting is great, and is often overlooked vs 3D printing. He purchased some hardware store RTV silicone and some slow-cure resin. The faster cure resin would get too hot with this much volume and potentially burn.

Materials procured he took apart both gearboxes from the machine. He first made a silicone mold of the broken parts (from the good copies out of the working gearbox) and removed the master. Without a vacuum or pressure casting chamber, the molds came out a little rough and bubbly, but it’s nothing some work with a carpet knife can’t fix. For big gears like this it hardly matters. Next he poured the two part resin into the molds and waited.

After some finishing with regular woodworking tools the parts fit right into the voids in the defective gearbox. His son can once again happily whir around the lawn, until the batteries die anyway.

Soviet-Era Tank Gets The 3D Printed Treatment

3D printers are celebrated for their capacity to replace missing or broken parts. How about an entire T-62 tank?

Now hold on a second — this is only a model replica. It is, however another expression of the myriad uses for 3D printers. Designed in Maya and requiring almost three weeks to print all 62 parts from about 70 meters of PLA filament.  The assembly is not terribly involved, made easier by printing a few large sections such as the crew section and hull while the parts don’t get much smaller than the turret hatches. Nonetheless, he final product is about as true to life as you can get when designing the parts from scratch.

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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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R/C Hot Rod Built Completely From Scratch

[ossum]’s R/C hot rod shows what’s possible when a talented hacker takes full advantage of all the modern resources available to them. The results are stunning.

[ossum] had a stack of Amazon and Shapeways credits lying around after winning a few competitions. He had this dream of building an R/C car for a while, and decided now was the time. After ordering all the needed parts from Amazon, he made an extremely nice model of the car in Fusion 360. The CAD model is a great learning resource. If you want to learn how to use reference photos, parts, and more to build a detailed and useful CAD model we recommend downloading it as a Fusion archive and scrubbing through the timeline to see how he did it.

Some of the parts were sent off for laser cutting. Others were 3D printed. The rest he made himself. Thanks to his model, they all went together well. You can see his R/C rod racing in the video after the break.

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The Citadel is the King of K’nex Builds.

Following one’s passion can lead to amazing results. Sometimes this results in technological marvels; other times, one marvels at the use of the technology. An exemplary display of the latter is The Citadel.

Over the course of three years, redditor [Shadowman39] pieced together this monstrous K’nex structure. With over 17 different paths(!), 45 different elements, and over 40,000 parts, you would expect some meticulous planning to go into its construction — but that’s not the case! [Shadowman39] assembled it largely on the fly with only a few elements needing to be sketched out and only the main elevator proving to be troublesome. Three motors power the structure — one for the main elevator, one for the smaller lifts on the bottom, and one for the release gates.

This is an absolute leviathan hobby project. To satiate the obvious curiosity of anyone who stumbles across this picture, its intricacies can be seen in the video:

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Reverse Engineering Quadcopter Protocols

Necessity is the mother of invention, but cheap crap from China is the mother of reverse engineering. [Michael] found a very, very cheap toy quadcopter in his local shop, and issued a challenge to himself. He would reverse engineer this quadcopter’s radio protocol. His four-post series of exploits covers finding the right frequency for the radio, figuring out the protocol, and building his own remote for this cheap toy.

[Michael] was already familiar with the capabilities of these cheap toys after reading a Hackaday post, and the 75-page, four language manual cleared a few things up for him. The ‘Quadro-Copter’ operated on 2.4GHz, but did not give any further information. [Michael] didn’t know what channel the toy was receiving on, what data rate, or what the header for the transmission was. SDR would be a good tool for figuring this out, but thanks to Travis Goodspeed, there’s a really neat trick that will put a 2.4GHz nRF24L01+ radio into promiscuous mode, allowing [Michael] to read the transmissions between the transmitter and quadcopter. This code is available on [Michael]’s github.

A needle in an electromagnetic haystack was found and [Michael] could listen in on the quadcopter commands. The next step was interpreting the ones and zeros, and with the help of a small breakout board and soldering directly to the SPI bus on the transmitter, [Michael] was able to do just that. By going through the nRF24 documentation, he was able to suss out the pairing protocol and read the stream of bytes that commanded the quadcopter.

What [Michael] was left with is a series of eight bytes sent in a continuous stream from the transmitter to the toy. These bytes contained the throttle, yaw, pitch, roll, and a ‘flip’ settings, along with three bytes of ‘counters’ that didn’t seem to do anything.  With that info in hand, [Michael] took an Arduino Nano, an nRF04L01+ transceiver, and a Wii nunchuck to build his own transmitter. If you’re looking for a ‘how to reverse engineer’ guide, it generally doesn’t get better than this.

You can check out a video of [Michael] flying his Wiimoted quadcopter below.

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Real World Race Track is Real Hack

[Rulof] never ceases to impress us with what he comes up with and how he hacks it together. Seriously, how did he even know that the obscure umbrella part he used in this project existed, let alone thought of it when the time came to make a magnet mount? His hack this time is a real world, tabletop race track made for his little brother, and by his account, his brother is going crazy for it.

His race track is on a rotating table and consists of the following collection of parts: a motor, bicycle wheel, casters from a travel bag, rubber bands (where did he get such large ones?), toy car and steering wheel from his brother, skateboard wheels, the aforementioned umbrella part and hard drive magnets. In the video below we like how he paints the track surface by holding his paint brush fixed in place and letting the track rotate under it.

From the video you can see the race track has got [Rulof] hooked. Hopefully he lets his brother have ample turns too, but we’re not too sure. Some additions we can imagine would be robotics for the obstacles, lighting, sounds and a few simulated explosion effects (puffs of flour?).

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