Dambusting, R/C Style

November 23, 2019 by Dan Maloney 22 Comments

Disclaimer: no dams were actually busted in the making of the video below. But that doesn’t mean that a scale-model homage to the WWII Dam Busters and their “Bouncing Bombs” isn’t worth doing, of course.

In a war filled with hacks, [Barnes Wallis]’ Bouncing Bomb concept might just be the hackiest. In the video below, [Tom Stanton] explains that [Wallis] came up with the idea of skipping a bomb across the surface of a lake to destroy enemy infrastructure after skipping marbles across the water. Using barrel-shaped bombs, he built a rig that could give them the proper amount of backspin and release them at just the right time, letting them skip across the surface of the lake while the bomber made an escape. Upon hitting the rim of the dam, the bomb would sink to explode near the base, maximizing damage.

[Tom]’s scale rig ended up being a clever design with spring-loaded arms to release a 3D-printed barrel after being spun up by a brushless motor. He teamed up with R/C builder [James Whomsley], who came up with a wonderful foam-board Lancaster bomber, just like RAF No. 617 Squadron used. With a calm day and smooth water on the lake they chose for testing, the R/C Lanc made a few test runs before releasing the first barrel bomb. The first run was a bit too steep, causing the bomb to just dive into the water without skipping. Technical problems and a crash landing foiled the second run, but the third run was perfect – the bomb skipped thrice while the plane banked gracefully away. [Tom] also tried a heavy-lift quadcopter run with the bomb rig, something [Barnes Wallis] couldn’t even have dreamed of back in the day.

Hats off to [Tom] and [James] for collaborating on this and getting the skipping to work. It reminds us a bit of the engineered approach to rock-skipping, though with less deadly intentions.

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Giant Analog CO2 Meter Sweeps Away Doubt

November 14, 2019 by Kristina Panos 11 Comments

Most of us are aware that trees turn CO₂ into oxygen, but we’d venture to guess that many people’s knowledge of this gas ends there. Is it feast or famine out there for the trees? Who can say? We admire [rabbitcreek]’s commitment to citizen science because he’s so focused on making it easy for people to understand their environment. His latest offering, a giant analog CO₂ meter, might be our favorite so far.

The brains of the operation is an Adafruit Feather Adalogger. It reads the CO₂ sensor that’s mounted close to the business end of the nautilus, and becomes the quill that writes the CO₂ value to a FeatherWing e-ink screen. For the giant needle, this lovely meter uses one of those fiberglass poles you mark your driveway with so you can find it under a blanket of snow. The needle is counter-balanced with washers encased in printed plastic.

As you can see in the GIF, there’s a decent delay between the CO₂ blast and the needle response — we like to imagine the CO₂ spiraling slowly through the nautilus like a heavy, ill wind on its way to gravely move the needle.

Want a way to monitor air quality that’s a bit more discreet? Slip this portable meter into your pocket.

This Arduino Keeps Its Eyes On You

November 13, 2019 by Al Williams 5 Comments

[Will] wanted to build some animatronic eyes that didn’t require high-precision 3D printing. He wound up with a forgiving design that uses an Arduino and six servo motors. You can see the video of the eyes moving around in the video below.

The bill of materials is pretty simple and features an Arduino, a driver board, and a joystick. The 3D printing parts are easy to print with no supports, and will work with PLA. Other than opening up holes there wasn’t much post-processing required, though he did sand the actual eyeballs which sounds painful.

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Mechanical Seven-Segment Display Mixes Art With Hacking

November 11, 2019 by Dan Maloney 28 Comments

We’re not sure what to call this one. Is it a circuit sculpture? Sort of, but it moves, so perhaps it’s a kinetic circuit sculpture. Creator [Tomohiro Tsuchita] calls it “something beautiful but totally useless,” which we find a tad harsh. But whatever you call it, we think this mechanical seven-segment display is really, really cool.

Before anyone gets to thinking that this is something like the other mechanical seven-segment displays we’ve seen lately, think again. This one is not addressable; it simply goes through the ten digits in order. So you won’t be building a clock from it, although we suppose the mechanism could be modified to allow that. Then again, looking at that drive train of laser-cut acrylic cams, maybe not. Each segment has its own cam with lobes or valleys for each segment. A cam follower lowers and raises the segments as the cams rotate on a common shaft. A full-rotation servo powers the display under the control of a Micro:bit; the microcontroller is overkill for now but will be used in version two, which will allow the speed to change in response to sensors.

Watching this display change at its stately pace is strangely soothing. We love the look of this, but then again, we’re partial to objets d’art-circuit. After all, we ran a circuit sculpture contest earlier in the year, and just wrapped up a Hack Chat dedicated to the subject.

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Servo Socks Is A Brilliantly Simple Solution For Quick Hacking

November 5, 2019 by Gerrit Coetzee 8 Comments

[Dan Kitchen] has a great solution for making servos easy to hack.

Every hacker has a drawer full of servo’s somewhere. Just about every project that uses them starts off by measuring the spacing and designing some obscure bracket to meet that unique motor’s size. However, what if you could use common wood screws and hand tools to use them right away?

[Dan]’s solution is to make a case from recycled HDPE lumber, the same sort of material you might buy for a deck. This material is sandable, carvable, and can be drilled into. The case encapsulates the servo motor completely. One side has a freewheeling wooden disk and the other side’s disk is attached to the motor. Now when you need motion you can work with the servo as if it were just a block of wood. Very cool.

[Dan] appears to be moving to make this a commercial product and we can see why. Though we see no reason why an enterprising hacker or hackerspace couldn’t come up with their own variations on this great idea.

Haptic Glove Controls Robot Hand Wirelessly

October 25, 2019 by Al Williams No comments

[Miller] wanted to practice a bit with some wireless modules and wound up creating a robotic hand he could teleoperate with the help of a haptic glove. It lookes highly reproducible, as you can see the video, below the break.

The glove uses an Arduino’s analog to digital converter to read some flex sensors. Commercial flex sensors are pretty expensive, so he experimented with some homemade sensors. The ones with tin foil and graphite didn’t work well, but using some bent can metal worked better despite not having good resolution.

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A (Mostly) 3D Printed Servo/Gear Reduction

October 14, 2019 by Sharon Lin 5 Comments

This servo/gear reduction was assembled with almost all 3D-printed parts. Apart from a brushed 36 V DC-motor, a stainless steel shaft, and screws for holding the servo together, the only other non-printed part is the BTS7960B motor driver.

Some interesting stats about the plastic servo – its stall torque is about 55 kg/cm, reaching a peak current draw of 18 A when using a 6s LiPo battery outputting 22-24 V. The shaft rotates using two 20 mm holes and lubrication. (Ball bearings were originally in the design, but they didn’t arrive on time for the assembly.)

The holes of the gears are 6.2 mm in diameter in order to fit around the shaft, although some care is taken to sand or fill the opening depending on the quality of the 3D print.

This isn’t [Brian Brocken]’s only attempt at 3D-printing gears. He’s also built several crawling robots, a turntable, and a wind up car made entirely from acrylic. The .stl files for the project are all available online for anyone looking to make their own 3D-printed servo gears.

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