A Honeycomb Patching Robot Powered By Arduino

March 3, 2020 by Tom Nardi 13 Comments

No, it’s not the kind of honeycomb you’re probably thinking of. We’re talking about the lightweight panels commonly used in aerospace applications. Apparently they’re rather prone to dents and other damage during handling, so Boeing teamed up with students from the California State University to come up with a way to automate the time-consuming repair process.

The resulting machine, which you can see in action after the break, is a phenomenal piece of engineering. But more than that, it’s an impressive use of off-the-shelf components. The only thing more fascinating than seeing this robotic machine perform its artful repairs is counting how many of its core components you’ve got laying around the shop.

Built from aluminum extrusion, powered by an Arduino Due, and spinning a Dewalt cut-off tool that looks like it was just picked it up from Home Depot, you could easily source most of the hardware yourself. Assuming you needed to automatically repair aerospace-grade honeycomb panels, anyway.

At the heart of this project is a rotating “turret” that holds all the tools required for the repair. After the turret is homed and the condition of all the cutting tools is verified, a hole is drilled into the top of the damaged cell. A small tool is then carefully angled into the hole (a little trick that is mechanical poetry in motion) to deburr the hole, and a vacuum is used to suck out any of the filings created by the previous operations. Finally a nozzle is moved into position and the void is filled with expanding foam.

Boeing says it takes up to four hours for a human to perform this same repair. Frankly, that seems a little crazy to us. But then again if we were the ones tasked with repairing a structural panel for a communications satellite or aircraft worth hundreds of millions of dollars, we’d probably take our time too. The video is obviously sped up so it’s hard to say exactly how long this automated process takes, but it doesn’t seem like it could be much more than a few minutes from start to finish.

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This DIY Dynamometer Shows Just What A Motor Can Do

March 2, 2020 by Dan Maloney 11 Comments

Back in high school, all the serious gearheads used to brag about two things: their drag strip tickets, and their dynamometer reports. The former showed how fast their muscle car could cover a quarter-mile, while the latter was documentation on how much power their carefully crafted machine could deliver. What can I say; gas was cheap and we didn’t have the Internet to distract us.

Bragging rights are not exactly what [Jeremy Fielding] has in mind for his DIY dynamometer, nor is getting the particulars on a big Detroit V8 engine. Rather, he wants to characterize small- to medium-sized electric motors, with an eye toward repurposing them for different projects. To do this, he built a simple jig to measure the two parameters needed to calculate the power output of a motor: speed and torque. A magnetic tachometer does the job of measuring the motor’s speed, but torque proved a bit more challenging. The motor under test is coupled to a separate electric braking motor, which spins free when it’s not powered. A lever arm of known length connects to the braking motor on one end while bearing on a digital scale on the other. With the motor under test spun up, the braking motor is gradually powered, which rotates its housing and produces a force on the scale through the lever arm. A little math is all it takes for the mystery motor to reveal its secrets.

[Jeremy]’s videos are always instructional, and the joy he obviously feels at discovery is infectious, so we’re surprised to see that we haven’t featured any of his stuff before. We’ve seen our share of dynos before, though, from the tiny to the computerized to the kind that sometimes blows up.

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The Last Scientific Calculator?

March 2, 2020 by Al Williams 105 Comments

There was a time when being an engineering student meant you had a sword. Well, really it was a slide rule hanging from your belt, but it sounds cooler to call it a sword. The slide rule sword gave way to calculators hanging from your belt loop, and for many engineers that calculator was from HP. Today’s students are more likely to have a TI or Casio calculator, but HP is still in there with the HP Prime. It is hard to call it a calculator since the latest variant has a 528 MHz ARM Cortex A7, 256 MB of RAM, and 512 MB of ROM. But if you can’t justify a $150 calculator, there are some cheap and even free options out there to get the experience. To start with, HP has a free app that runs on Windows or Mac that works just like the calculator. Of course, that’s free as in no charge, not free as in open source. But still, it will run under Wine with no more than the usual amount of coaxing.

You might wonder why you need a calculator on your computer, and perhaps you don’t. However, the HP Prime isn’t just your 1980s vintage calculator. It also has an amazing number of applications including a complete symbolic math system based on xCAS/Giac. It is also programmable using a special HP language that is sort of like Basic or Pascal. Other applications include plotting, statistics, solvers, and even a spreadsheet that can hold up to 10,000 rows and 676 columns.

Portability

It is easy to think that HP provides the free PC software so you’ll go out and buy the real calculator, and that may be part of it. However, you can also get official apps for Android and iOS. They aren’t free, but they are relatively inexpensive. On iOS the cost right now is $25 and on Android it is $20. There are also “lite” versions that are free.

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Desktop PCB Mill Review

February 29, 2020 by Al Williams 19 Comments

[Carl] wanted to prototype his circuits quickly using printed circuit boards. He picked up a Bantam Tools Desktop PCB Mill and made a video about the results. His first attempt wasn’t perfect, as you could notice under the microscope. A few adjustments, though, and the result was pretty good.

Be warned, this mill is pretty expensive — anywhere from $2,500 to $3,000. The company claims it is a better choice than a conventional cheap mill because it uses a 26,000 RPM spindle and has high-resolution steppers. Because of its low backlash and high accuracy and repeatability, the company claims it can easily mill boards with 6 mil traces.

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A Simple Yet Feature-Packed Programmable DC Load

February 28, 2020 by Dan Maloney 14 Comments

If you’ve got the hankering to own a lab full of high-end gear but your budget is groaning in protest, rolling your own test equipment can be a great option. Not everything the complete shop needs is appropriate for a DIY version, of course, but a programmable DC load like this one is certainly within reach of most hackers.

This build comes to us courtesy of [Scott M. Baker], who does his usual top-notch job of documenting everything. There’s a longish video below that covers everything from design to testing, while the link above is a more succinct version of events. Either way, you’ll get treated to a good description of the design basics, which is essentially an op-amp controlling the gate of a MOSFET in proportion to the voltage across a current sense resistor. The final circuit adds bells and whistles, primarily in the form of triple MOSFETS and a small DAC to control the set-point. The DAC is driven by a Raspberry Pi, which also supports either an LCD or VFD display, an ADC for reading the voltage across the sense resistor, and a web interface for controlling the load remotely. [Scott]’s testing revealed a few problems, like a small discrepancy in the actual amperage reading caused by the offset voltage of the op-amp. The MOSFETs also got a bit toasty under a full load of 100 W; a larger heatsink allows him to push the load to 200 W without releasing the smoke.

We always enjoy [Dr. Baker]’s projects, particularly for the insight they provide on design decisions. Whether you want to upgrade the controller for a 40-year-old game console or giving a voice to an RC2014, you should check out his stuff.

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A Rope Maker You Can 3D Print At Home

February 24, 2020 by Lewin Day 11 Comments

Ropes are one of those things that, while possible to make by hand, having a little mechanical help goes a long way in their manufacture. [b33ma247] wanted just such a rig, so set about building one from scratch.

It’s a simple device, but one that makes the task much easier. A series of gears are printed, which assemble on to a frame to form the winding mechanism that weaves the rope. There’s also a slide, a rope separator, and a weight carriage to ensure proper tension is kept on the string during the weaving process. The mechanism is driven by a power drill, though this could be easily replaced with a hand crank if full manual operation was desired.

It’s a project which shows if you have a 3D printer, you can make a lot of other useful tools for your workshop too. We see similar approaches taken when it comes time to wind coils, too. Video after the break.

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3D Printed Breadboard Helper Makes Wiring Neater And Easier

February 23, 2020 by Al Williams 25 Comments

Breadboards make it simple to prototype and test circuits. If you use flexible wires with pins to make connections, it usually results in a rat’s nest. For many of us, using solid wire makes a rat’s nest, too. However, the very neat among us will cut solid wire to just the right length and strip just the right amount of wire and lay the wires very flat and neat along the board. [Moononournation] did a 3D print that makes the latter method much easier. You can find his Breadboard Wire Helper on Thingiverse and see a video, below.

The idea is simple: start with a piece of wire stripped on one side, then count out the number of holes it needs to traverse and push the stripped end through the hole. Trim the wire to fit. To complete the other side, lay the wire flat along the tool to the edge. Now you can see where to strip that side of the wire. After you remove the insulation, you can bend the wire down and cut the wire to fit. Now you have a perfect size and shape wire to place in the actual breadboard.

Granted, this isn’t that hard to do with the existing breadboard if it isn’t too packed. You could even use a spare breadboard. But it is a little easier to trim the wire to the right size with this jig. If you don’t want to 3D print it, you could probably pull the tape off the back of a cheap board and remove the springs to get a similar effect.

So while this little tool probably won’t change your life, it might make it a little easier. What other tools do you use when breadboarding? Let everyone know in the comments.

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