AI On The Highway

January 5, 2021 by Chris Lott 13 Comments

A couple of announcements caught our attention last week regarding AI-controlled cars. South Korea’s Kakao Mobility and local startup Autonomous A2G launched a limited self-driving taxi service in Sejong City this month, made possible by enabling legislation passed in May. For now, the service is restricted to government employees, and the AI driver will be backed-up by an engineer who is there to monitor the systems and take over in an emergency. The companies plan to expand the fleet and service areas this year, although no details are given.

Another announcement comes from the Ministry of Land, Infrastructure and Transport about the on-going successes of the semi-autonomous truck platooning program. This is a collaboration between the Korean Expressway Corporation, Kookmin University in Seoul, and Hyundai Motors. Previously restricted to a designated test road called the Yeoju Smart Highway, the program is now being tested on public roads at speeds up to 70 kph. This year the program will expand to platoons of 4 trucks running at 90 kph. We’ve always thought that long-haul trucking and freight industries would be an early adaptor AI technologies, and one which AI could offer significant benefits.

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ABS Mercedes Rims Push The Limits Of 3D Printing

January 3, 2021 by Danie Conradie 49 Comments

While we’re big believers in 3D printing here at Hackaday, there’s no denying that some things just aren’t meant to be printed. For example, most of us would agree that it’s not the first choice for making rims for a passenger car. We imagine that [Jón Schone] from Proper Printing probably feels the same way, but that didn’t stop him from trying to do it anyway.

A couple of months ago [Jón] got a test subject in the form of an older Mercedes with 19-inch rims. The first two challenges are bed size and warping, so he modified a Creality CR10 S5 with a heated chamber capable of reaching 70 °C to reduce warping with the ABS filament he intended to use. Another challenge is the amount of filament required for the print, especially since [Jón] wasn’t keen on babysitting the machine to replace the spool every so often. His attempt at building a filament joiner ultimately didn’t work out, so in the end he simply sourced the filament in bulk size rolls.

Bolts hold the two halves of the rim together.

Eventually [Jón] managed to print a complete rim in two halves, bolted together around its circumference. Unfortunately, even with the heated chamber, the parts still warped all around the edges. This left a gap at the seam, but to fit a tubeless tire, the rim had to be airtight. So the entire inside surface was painted to close any small gaps, and the larger gaps were filled with sealant.

In the end it was still unable to hold pressure with a tire mounted, so it was test fitted to the car just to see if it would carry the weight. This test also failed, splitting on the thinnest part of the rim. [Jón] has headed back to the drawing board to try again in 2021. We probably would have moved on by now, but you have to admire his tenacity. We hope to see success in the new year.

Printing large parts brings its own set of challenges, but if you stick to good old PLA it’s not too difficult. [Ivan Miranda] has made a name for himself with massive 3D printed projects like a ride-able tank, and also built a supersized 3D printer for future projects.

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Build Your Own Custom Elevator

December 28, 2020 by Bryan Cockfield 67 Comments

There are a lot of things in our everyday life that are holdovers from an earlier time that we continue to use simply because of inertia even if they don’t make a lot of sense in modern times. Examples include a 60 Hz power grid, the spacing between railroad tracks, and of course the self-contained attic ladder which is made to fit in between standard spaced ceiling joists. It’s not wide enough to get big or heavy stuff into an attic, and building standards won’t change just for this one inconvenience, so if you want to turn that space into something more usable you’re going to need to build a custom elevator.

This attic elevator comes to us from [Brian] who recently moved into a home with about half the square footage as his previous home, but still needed to hold all of his stuff. That means clever ways of using the available space. For the elevator he constructed a platform out of 2x lumber held together with bolts and steel supports. The carriage runs up and down on a track made out 1 5/8″ super strut and is hoisted by a winch motor rated for 550 pounds, which is more than enough to hoist up most household items including a large toolbox.

The only thing that we would have liked to have seen in the video is how the opening was made. Presumably this would have involved cutting into a ceiling joist to make the opening wider than the standard attic ladder, and care would have needed to be taken to ensure the ceiling/floor wasn’t weakened. Either way, this is a great solution to a common problem, and could perhaps be made to work on more than two levels with a custom controller. Continue reading “Build Your Own Custom Elevator” →

Casting Skateboard Wheels With A 3D Printed Mold

December 26, 2020 by Tom Nardi 7 Comments

We’ll admit that most of the Hackaday staff wouldn’t get too far on a skateboard, but that doesn’t mean we can’t appreciate the impressive DIY wheels that [Chris McCann] has managed to cast using 3D printed molds. From unique color combinations to experimental materials, the process certainly opens up some interesting possibilities for those looking to truly customize their rides. Though it’s worth noting there’s a certain element of risk involved; should a set of homemade wheels fail at speed, it could go rather poorly for the rider.

Both the STL and STEP files for the mold have been released under the Creative Commons Attribution 4.0 license, meaning anyone with a 3D printer can follow along at home. Unfortunately, it’s not quite as simple as clicking print and coming back to a usable mold. Because of the layer lines inherent to FDM 3D printing, the inside of the mold needs to be thoroughly sanded and polished. [Chris] mentions that printing the mold in ABS and using vapor smoothing might be a workable alternative to elbow grease and PLA, but he hasn’t personally tried it yet.

Once you’ve got the three part mold printed, smoothed, and coated with an appropriate release agent like petroleum jelly, it’s time to make some wheels. The core of each wheel is actually 3D printed from PETG, which should give it pretty reasonable impact resistance. If you have access to a lathe, producing aluminum cores shouldn’t be too difficult either. With the core loaded into the mold, urethane resin is poured in through the top until all the empty space is filled.

But you’re not done yet. All those little air bubbles in the resin need to be dealt with before it cures. [Chris] puts his filled molds into a pressure chamber, though he mentions that vacuum degassing might also be a possibility depending on the urethane mixture used. After everything is solidified, the mold can easily be taken apart to reveal the newly cast wheel.

While there’s often some trial and error involved, 3D printing and resin casting are an undeniably powerful combination. If you can master the techniques involved, you can produce some very impressive parts that otherwise would be exceptionally difficult to produce on a hacker’s budget. Especially when you’re ready to start casting molten metal.

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Tank Track Skateboard

December 25, 2020 by Danie Conradie 8 Comments

As electric skateboards kits and components become more commonly available, you really need to do something different to make your custom board stand out. [Emiel] [The Practical Engineer] has managed to do this by building a half-track skateboard. (Video, embedded below.)

Except for the front trucks, fasteners and bearings, all the mechanical components on the board were custom-made. The sturdy rear chassis and the track sections were machined from aluminum plate, and the wheels and track linkages were machined from POM/Delrin. The large carbon fiber deck and the polyurethane pads on the tracks were custom molded, which [Emiel] covered in detail in separate videos, also below. Two beefy brushless motors drive the tracks and are powered by LiPos in enclosed in the sheet metal electronics box. The final product looks very well-built and refined, especially considering most of the work happened in a tiny 2 m x 3 m workshop.

It looks like the board handles gravel paths well, but we would really like to see how it performs on soft surfaces like sand, where even off-road skateboards can struggle. It struggled a bit with low RPM torque, so a slight gearing change is in this board’s future.

Everything is cooler with tank tracks. If you’re willing to live with plastic tracks, 3D printing is a viable option, as demonstrated by [rctestflight]’s tracked rover and [Ivan Miranda]’s tank skateboard. Continue reading “Tank Track Skateboard” →

Radio Controlled Hovercraft Apes The SR.N1

December 15, 2020 by Lewin Day 7 Comments

Hovercraft never really caught on as regular transportation, but they are very cool. The Saunders-Roe SR.N1 was the very first practical example of the type, and served as a research vehicle to explore the dynamics of such vehicles. [mr_fid] was looking for a lockdown project, and set about crafting a radio controlled replica of his own.

The build is crafted out of a canny combination of plywood and balsa, the latter substituted in sections within the plywood hull to save weight. A pair of brushless outrunner motors are mounted in the central duct to provide lift, fitted with counter-rotating propellers in order to avoid torque effects on handling. Steering is via puff ports a la the original design, which allows the craft to spin very quickly in place to much amusement and no practical effect. The skirt is of a colorful design, carefully assembled out of polyurethane-coated nylon.

While it’s not the quickest way to build a hovercraft, it’s all the more beautiful for its attention to the details and function of the original prototype craft. We particularly like the sharp handling thanks to the puff port design. If you’re looking for a weirder design however, consider this Coanda Effect build. Video after the break.

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RC Starship Perfects Its Skydiving Routine

December 13, 2020 by Tom Nardi 12 Comments

There’s a good chance you already saw SpaceX’s towering Starship prototype make its impressive twelve kilometer test flight. While the attempt ended with a spectacular fireball, it was still a phenomenal success as it demonstrated a number of concepts that to this point had never been attempted in the real world. Most importantly, the “Belly Flop” maneuver which sees the 50 meter (160 foot) long rocket transition from vertical flight to a horizontal semi-glide using electrically actuated flight surfaces.

Finding himself inspired by this futuristic spacecraft, [Nicholas Rehm] has designed his own radio controlled Starship that’s capable of all the same aerobatic tricks as the real-thing. It swaps the rocket engines for a pair of electric brushless motors, but otherwise, it’s a fairly accurate recreation of SpaceX’s current test program vehicle. As you can see in the video after the break, it’s even able to stick the landing. Well, sometimes anyway.

Just like the real Starship, vectored thrust is used to both stabilize the vehicle during vertical ascent and help transition it into and out of horizontal flight. Of course, there are no rocket nozzles to slew around, so [Nicholas] is using servo-controlled vanes in the bottom of the rocket to divert the airflow from the motors. Servos are also used to control the external control surfaces, which provide stability and a bit of control authority as the vehicle is falling.

As an interesting aside, Internet sleuths looking through pictures of the Starship’s wreckage have noted that SpaceX appears to be actuating the flaps with gearboxes driven by Tesla motors. The vehicle is reportedly using Tesla battery packs as well. So while moving the control surfaces on model aircraft with battery-powered servos might historically have been a compromise to minimize internal complexity, here it’s actually quite close to the real thing.

Unfortunately, the RC Starship made a hard landing of its own on a recent test flight, so [Nicholas] currently has to rebuild the craft before he can continue with further development. We’re confident he’ll get it back in the air, though it will be interesting to see whether or not he’s flying before SpaceX fires off their next prototype.

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