Fail Of The Week: Pinewood Derby Cheat Fails Two Ways

November 29, 2016 by Dan Maloney 85 Comments

Would you use your tech prowess to cheat at the Pinewood Derby? When your kid brings home that minimalist kit and expects you to help engineer a car that can beat all the others in the gravity-powered race, the temptation is there. But luckily, there are some events that don’t include the kiddies and the need for parents to assume the proper moral posture. When the whole point of the Pinewood Derby is to cheat, then you pull out all the stops, and you might try building an electrodynamic suspension hoverboard car.

Fortunately for [ch00ftech], the team-building Derby sponsored by his employer is a little looser with the rules than the usual event. Loose enough perhaps to try a magnetically levitating car. The aluminum track provided a perfect surface to leverage Lenz’s Law. [ch00ftech] tried different arrangements of coils and drivers in an attempt to at least reduce the friction between car and track, if not outright levitate it. Sadly, time ran out and physics had others ideas, so [ch00ftech], intent on cheating by any means, tried spoofing the track timing system with a ridiculous front bumper of IR LEDs. But even that didn’t work in the end, and poor [ch00f]’s car wound up in sixth place.

So what could [ch00ftech] had done better? Was he on the right course with levitation? Or was spoofing the sensors likely to have worked with better optics? Or should he have resorted to jet propulsion or a propeller drive? How would you cheat at the Pinewood Derby?

Fail of the Week is a Hackaday column which celebrates failure as a learning tool. Help keep the fun rolling by writing about your own failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

LEGO Technics Machine Produces True Braided Rope

November 28, 2016 by Dan Maloney 24 Comments

We love a good LEGO build as much as anyone, but Technics takes it to the next level in terms of creating working mechanisms. And nobody takes Technics as far as [Nico71], as evidenced by his super-fast Technics rope braiding machine.

The last time we saw one of [Nico71]’s builds, it was also a LEGO Technics rope-making machine. At the time, we called it a “rope-braiding machine” and were taken to task in the comments since the strands were merely twisted to make the final product. [Nico71] must have taken that to heart, because the current build results in true braided cordage. That trick is accomplished by flying shuttles that are not attached to either of the two counter-rotating three-spoked wheels. The shuttles are transferred between the two wheels by a sweeper arm, each making a full revolution with one wheel before being transferred to the other. Each shuttle’s thread makes an intertwining figure-eight around the threads from the two fixed bobbins, and the result is a five-strand braided cord. The whole machine is mesmerizing to watch, and the mechanism is silky smooth even at high speeds. It seems like a much simpler design than the previous effort, too.

You’ve got to hand it to builders like [Nico71] that come up with fascinating machines while working within the constraints of the Technics world. And those that leverage the Technics platform in their builds can come up with pretty neat stuff, like this paper tape reader for a music machine.

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Glues You Can Use: Adhesives For The Home Shop

November 28, 2016 by Dan Maloney 72 Comments

A while back I looked at lubricants for the home shop, with an eye to the physics and chemistry behind lubrication. Talking about how to keep parts moving got me thinking about the other side of the equation – what’s the science behind sticking stuff together? Home shops have a lot of applications for adhesives, so it probably pays to know how they work so you can choose the right glue for the job. We’ll also take a look at a couple of broad classes of adhesives that are handy to have around the home shop. Continue reading “Glues You Can Use: Adhesives For The Home Shop” →

Quick Arduino Hack Lets Tach-less Car Display Shift Points

November 28, 2016 by Dan Maloney 42 Comments

A tachometer used to be an accessory added to the dash of only the sportiest of cars, but now they’re pretty much standard equipment on everything from sleek coupes to the family truckster. If your daily driver was born without a tach, fear not – a simple Arduino tachometer is well within your reach.

The tach-less vehicle in question is [deepsyx]’s Opel Astra, which from the video below seems to have the pep and manual transmission that would make a tach especially useful. Eschewing the traditional analog meter display or even a digital readout, [deepsyx] opted to indicate shift points with four LEDs mounted to a scrap of old credit card. The first LED lights at 4000 RPM, with subsequent LEDs coming on at each 500 RPM increase beyond that. At 5800 RPM, all the LEDs blink as a redline warning. [Deepsyx] even provides a serial output of the smoothed RPM value, so logging of RPM data is a possible future enhancement.

The project is sensing engine speed using the coil trigger signal – a signal sent from the Engine Control Unit (ECU) which tells one of the ignition coilpacks to fire. The high voltage signal from the coilpack passes on to the spark plug, which ignites the air-fuel mixture in that cylinder. This is a good way to determine engine RPM without mechanical modifications to the car. Just make sure you modify the code for the correct number of cylinders in your vehicle.

Simple, cheap, effective – even if it is more of a shift point indicator than true tachometer, it gets the job done. But if you’re looking for a more traditional display and have a more recent vintage car, this sweeping LED tachometer might suit you more.

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A Next-Level Home-Built Flight Simulator

November 26, 2016 by Dan Maloney 30 Comments

Every hobby needs to have a few people who take it just a little too far. In particular, the aviation hobbies – Radio control flying, FPV multicopter racing, and the like – seem to inspire more than their fair share of hard-core builds. In witness whereof we present this over-the-top home-brew flight simulator.

His wife and friends think he’s crazy, and we agree. But [XPilotSimPro] is that special kind of crazy that it takes to advance the state of the art, and we applaud him for that. A long-time fan of flight simulator games, he was lucky enough to log some time in a real 737 simulator. That seems to be where he caught the DIY bug. The video after the break is a whirlwind tour of the main part of his build, which does not seek to faithfully reproduce any particular cockpit as much as create a plausibly awesome one. Built on a PVC pipe frame with plywood panels, the cockpit is bristling with LCD panels, flight instruments, and bays of avionics that look like they came out of a cockpit. The simulator sits facing a wall with an overhead LCD projector providing views of the outside world. An overhead panel sporting yet more LCD panels and instruments was a recent addition. The whole thing is powered by a hefty looking gaming rig running X-Plane, allowing [XPilotSimPro] to take on any aviation challenge, including landing an Embraer 109 on the deck of the USS Nimitz Aircraft Carrier.

What could be next for [XPilotSimPro]’s simulator? How about adding a little motion control with pneumatics? Or better still, how about using a real 737 cockpit as a simulator?

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Low-cost Video Streaming With A Webcam And Raspberry Pi

November 25, 2016 by Dan Maloney 32 Comments

Some people will tell you that YouTube has become a vast wasteland of entertainment like the boob tube before it. Live streaming doesn’t help the situation much, and this entry level webcam live-stream server isn’t poised to advance the art.

We jest, but only a little. [Mike Haldas] runs a video surveillance company that sells all manner of web-enabled cameras and wondered what it would take to get a low-end camera set up for live streaming. The first step was converting the Zavio webcam stream from RTSP (real-time streaming protocol) to the standard that YouTube uses, RTMP (real-time messaging protocol). Luckily, FFmpeg handles that conversion, so he compiled it for his MacBook Pro and set up a proof of concept. It worked, but he needed a compact solution that would free up his laptop. Raspberry Pi to the rescue – after loading a bunch of libraries and a four-hour build and install of FFmpeg, the webcam was streaming 1080p video of [Mike]’s sales office. He was worried that the Pi wouldn’t have the power needed for the job, and that it would be unstable. But as of this writing, the stream below has been active for six days, and it’s riveting stuff.

Raspberry Pis are a staple in the audio streaming world, like this pro-grade FM broadcast streaming rack or this minuscule internet radio streamer. And of course there’s this quick and dirty, warm and fuzzy streaming baby monitor.

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A Dual-purpose Arduino Servo Tester

November 23, 2016 by Dan Maloney 8 Comments

RC flying is one of those multi-disciplinary hobbies that really lets you expand your skill set. You don’t really need to know much to get started, but to get good you need to be part aeronautical engineer, part test pilot and part mechanic. But if you’re going to really go far you’ll also need to get good at electronics, which was part of the reason behind this Arduino servo tester.

[Peter Pokojny] decided to take the plunge into electronics to help him with the hobby, and he dove into the deep end. He built a servo tester and demonstrator based on an Arduino, and went the extra mile to give it a good UI and a bunch of functionality. The test program can cycle the servo under test through its full range of motion using any of a number of profiles — triangle, sine or square. The speed of the test cycle is selectable, and there’s even a mode to command the servo to a particular position manually. We’ll bet the build was quite a lesson for [Peter], and he ended up with a useful tool to boot.

Need to go even further back to basics than [Peter]? Then check out this primer on servos and this in-depth guide.

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