Cardboard And Paperclip CNC Plotter Destined For Self-Replication

Last November, after [HomoFaciens]’ garbage-can CNC build, we laid down the gauntlet – build a working CNC from cardboard and paperclips. And now, not only does OP deliver with a working CNC plotter, he also plans to develop it into a self-replicating machine.

To be honest, we made the challenge with tongue firmly planted in cheek. After all, how could corrugated cardboard ever make a sufficiently stiff structure for the frame of a CNC machine? [HomoFaciens] worked around this by using the much less compliant chipboard – probably closest to what we’d call matboard here in the States. His templates for the machine are extremely well thought-out; the main frame is a torsion box design, and the ways and slides are intricate affairs. Non-cardboard parts include threaded rod for the lead screws, servos modified for continuous rotation, an Arduino, and the aforementioned paperclips, which find use in the user interface, limit switches, and in the extremely clever encoders for each axis. The video below shows highlights of the build and the results.

True, the machine can only move a pen about, and the precision is nothing to brag about. But it works, and it’s perfectly capable of teaching all the basics of CNC builds to a beginner, which is a key design goal. And it’s well-positioned to move to the next level and become a machine that can replicate itself. We’ll be watching this one very closely.

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Slim and Classy Word Clock Shows the Weather Too

Word clocks are a neat twist on traditional timepiece user interfaces. Spelling out the time with words and phrases rather than numerals fancies up a clock nicely. And if you add the current weather and forecast to the display, you get this attractive and handy word-based time and weather display.

For this clock, one of the many custom builds on [GMG]’s site that betray a certain passion for unusual timepieces, an 8×32 array of Neopixels lives behind a laser-cut sheet of steam-bent birch plywood. Each pixel is masked by either an alphanumeric character or an icon representing weather conditions. An ESP8266 fetches time and weather data and drives the display serially, controlling the color of each cell and building up the display. The video below shows the clock doing its thing.

Sure, we’ve featured plenty of word clocks before, even some with weather display, but we like the slim and understated design of this build. We’re particularly impressed by the lengths [GMG] took in packing as much capability into the 256-pixel display as possible, like the way “today” and “tomorrow” overlap. And if you’ve got an eye for detail, you might spot what gets displayed when it’s over 80° and 80% relative humidity.

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Smart Mirror Reflects Hacker

Did [TobiasWeis] build a mirror that’s better at reflecting his image? No, he did not. Did he build a mirror that’s better at reflecting himself? We think so. In addition to these philosophical enhancements, the build itself is really nice.

The display is a Samsung LCD panel with its inconvenient plastic husk torn away and replaced with a new frame made of wood. We like the use of quickly made 3D printed brackets to hold the wood at a perfect 90 degrees while drilling the holes for the butt joints. Some time with glue, band clamps, and a few layers of paint and the frame was ready. He tried the DIY route for the two-way mirror, but decided to just order a glass one after some difficulty with bubbles and scratches.

A smart mirror needs an interface, but unless you own stock in Windex (glass cleaner), it is nice to have a way to keep it from turning into an OCD sufferer’s worst nightmare. This is, oddly, the first justification for the Leap Motion controller we can really buy into. Now, using the mirror does not involve touching the screen. [Tobias] initially thought to use a Raspberry Pi, but instead opted for a mini-computer that had been banging around a closet for a year or two. It had way more go power, and wouldn’t require him to hack drivers for the Leap Motion on the ARM version of Linux.

After that is was coding and installing modules. He goes into a bit of detail about it as well as his future plans. Our favorite is programming the mirror to show a scary face if you say “bloody mary” three times in a row.

Wooden Antikythera Mechanism is Geared for Greatness

[Dave] builds custom wooden orreries, which are mechanical models of the solar system. It’s no surprise then that he’s interested in the Antikythera Mechanism—a small geared device discovered off the coast of the Greece in 1900 that is believed to be the first analog computer and one of the oldest known geared systems, built partly to predict the positions of celestial bodies in the solar system as it was understood in ancient Greece.

wooden-antikythera-mechanism[Dave] decided to build a wooden version of the Antikythera Mechanism as a proof of concept that it can be done in wood rather than the brass of the original. He also sought to incorporate all the modern theories of the device’s gear train. The entire system is made out of 6mm birch plywood that [Dave] cut by hand on a scroll saw. That’s right — no CNC or lasers here. This has as much to do with replicating the craftsmanship of the original as it does with practicality. Besides, the pitch of the gear teeth is too small to be effectively cut with a laser.

There are no motors, either. The gears are centrally connected to nested brass tubing and the mechanism is actuated with a hand crank. The six pages of forum discussion are worth combing through just to see the pictures of [Dave]’s progress and all of those meticulously hand-cut gears.

It took [Dave] the better part of two years to complete this work of art, and you can see it in motion after the break. With the first version complete, he has begun Mk. II which will feature all of the spiral dials and pointers of the original. If you’re interested in exploring the Antikythera Mechanism further, here is Hackaday’s own in-depth look at it.

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The Open Source Hacker’s Laptop

[Tsvetan Usunov] has been Mr. Olimex for about twenty five years now, and since then, he’s been through a lot of laptops. Remember when power connectors were soldered directly to the motherboard? [Tsvetan] does, and he’s fixed his share of laptops. Sometimes, fixing a laptop doesn’t make any sense; vendors usually make laptops that are hard to repair, and things just inexplicably break. Every year, a few of [Tsvetan]’s laptops die, and the batteries of the rest lose capacity among other wear and tear. Despite some amazing progress from the major manufacturers, laptops are still throwaway devices.

Since [Tsvetan] makes ARM boards, boards with the ~duino suffix, and other electronic paraphernalia, it’s only natural that he would think about building his own laptop. It’s something he’s been working on for a while, but [Tsvetan] shared his progress on an Open Source, hacker’s laptop at the Hackaday | Belgrade conference.

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Searching for USB Power Supplies that Won’t Explode

USB power supplies are super cheap and omnipresent. They are the Tribble of my household. But they’re not all created equal, and some of them may even be dangerous. I had to source USB power supplies for a product, and it wasn’t easy. But the upside is that I got to tear them all apart and check out their designs.

In order to be legitimate, it’s nice (but not legally required) for a power supply to have UL approval. Some retailers and offices and building managers require it, and some insurance companies may not pay claims if it turns out the damage was caused by a non-UL-approved device.  UL approval is not an easy process, though, and it is time consuming and expensive. The good news is that if you are developing a low voltage DC product, you can pair it with a UL approved power supply and you’re good to go without any further testing necessary.

power_supply_1_overviewIf you are going for FCC approval and are having unintentional emissions testing done (which is more likely than UL as it’s a legal requirement for products that meet certain qualifications), the testing has to be done on the whole solution, so the power supply must be included in the testing, too.

Sourcing cheap electronics in large quantities usually ends up in China, and specifically Alibaba. First, we started with a how-low-can-you-go solution. This wasn’t even a power adapter; it was a power “adapteP”, and the whole batch was mis-printed. Quality control could not be a high priority. After cutting it open, it wasn’t terrible, and it had all the necessary parts. It was surprising how much of it was through-hole, which indicates that the assembly was done mostly by people. That happens when factories are cheaper, hire inexpensive labor, don’t invest in technology, and don’t care as much about quality.

There are certain things you should look for in a power supply to determine the level of risk:

  • Isolation Distance – This is how much space there is between the primary (AC) and secondary (DC 5V) sides. UL requires a few millimeters, and often you’ll see two separate PCBs. On many single-PCB solutions you’ll see a white line meander across the board to distinguish between the two. The smaller this separation, the closer your USB power is to AC line voltage, and if the gap is bridged somehow, you’re in for a world of hurt.
  • Fuse – if there is a short, a lot of current starts flowing, components heat up, and things get dangerous. A thermal cut-off (TCO) fuse (also known as a resettable fuse or a PTC) is a component that breaks the circuit when it gets too hot, like a circuit chaperon. When it cools off, the TCO resets and you can plug the device back in with no harm done. Without the fuse, the supply heats up and current keeps flowing until a component fries, sometimes explosively.
  • Connectors – You don’t want bare leads hanging out in space where they could move and touch something. You don’t want the USB port to be soldered only by its four pins. You don’t want the power pins to be loose.
  • Decent Label – “Adaptep”? Yes, to someone who uses a different alphabet the “P” and R are very similar characters. But still. Also, fake certifications abound. Look for the difference between the CE (China Export) and the CE (Conformité Européenne) labels. And the UL Logo should have a number. So should an FCC label.

So this first adapter? Isolation distance was fine because it was two separate boards, but there was no fuse and no protective tape between components. The connectors were all secure, but the label didn’t make any promises. As for performance, output at 5.34V under my product’s load meant it was a little outside of USB spec (5.25V limit), but not dangerous. On the scope it was ringing with a peak at 5.5 V at 4 kHz.

Of course, sourcing this supply for a second batch proved tricky, and we wanted the USB plug to come out the side instead of the front so it would have a thinner profile against a wall. Additionally, we needed UL approval for a client. Our second attempt was surprisingly successful. This adapter had UL certification, with a number to look up. Note that just having a number isn’t enough; many companies will just put someone else’s number on their product and assume nobody will bother to check. So when you do look it up, and find a different manufacturer, a different enclosure, and it looks more like a refrigerator than a USB power supply, don’t be too surprised. But no, this particular one was great! The label had a company name on it, model number and specs, and certifications that could be verified. Let’s tear it open!

power_supply_2_overviewSweet sweet silicon meat inside an ABS shell! Components wrapped in protective tape, two PCBs for isolation, and even a special injection-molded plastic piece to add additional protection. Components are labeled, and what’s this, an IC to control the oscillation instead of a feedback winding on the transformer? Fancy! It’s pretty clear that this power supply is good, and I’d trust this one.

Comparing this one to the others, there were so many noticeable little details that are important and clearly thought-out. Take, for example, the connection between the prongs and the PCB. On the previous board, it was made with wires soldered by hand. Solid, but time consuming and prone to failure or quality issues. This adapter has metal contacts that snap into the case very solidly so that the prongs cannot get loose. The connection to the PCB is via the springiness of the metal, but notice that the PCB has pads specifically designed to maximize the surface area of that connection. On the next PCB you’ll see no such effort.

Some components were covered in shrink tube, tape, or non-conductive grey adhesive. The assembly was tight with no room for components to shake loose or accidentally touch. And the output was perfect. 4.9 Volts with nary a ripple.

But this is China, and component sourcing problems are a thing, so I guess I shouldn’t have been surprised when these supplies were no longer available. In retrospect, maybe these were unsold overstock, or possibly QC rejects. That would explain why they were only slightly more expensive than the others. And so we moved on to another supplier; one that could pad-print our logo on top.

power_supply_differencesAt first glance these power supplies appeared identical. But close inspection reveals slight differences in the style around the USB and the raised ridges on the underside. The label was completely different, and gone was the number next to the UL logo. There was no company name on the supply either, and the company we purchased from turned out to be a reseller and not the OEM. Also, why was the output 4.7-5V, and why did my scope say 5.5V (but surprisingly stable)?

Inside was a completely different beast. Using a single PCB, the creep distance was about a millimeter. You can see the white line meandering through the bottom of the PCB that shows the high and low sides. The USB port wasn’t soldered to the PCB except by the four signal/power pins (see the bottom side lower left and the hanging USB connection pins), and there was a capacitor with really long uncovered leads and the positive side dangerously close to the USB shell. There was almost no protective tape, no shrink tube on the leads, and no protection in case of a short.

 

In the end, I wouldn’t trust the two non-UL supplies with anything worth more than a few bucks, and certainly not my cell phone. I’d have really big reservations about reselling them to customers who don’t know the difference. The UL-approved one was great, but the other two are only good for powering low-current-draw devices that are not sensitive to voltage. Also, finding a reliable supplier in China is HARD.

Check out a much more thorough analysis of this and pretty much every USB power supply cube by [Ken Shirriff]. It’s surprising how little has changed in four years with these supplies, and his analysis goes into how the circuits behind these supplies work, identifying each component and its purpose.

We also covered a Sparkfun teardown of some power supplies with similar conclusions, and a Fail of the Week in which a faulty USB power adapter was the likely cause of a fire.

The Incredible Success of World Create Day

When people come together, great things happen. Last weekend, the Hackaday Community all over the world self organized and came together in 64 cities for World Create Day. It was a coalescence of people who want to make a difference in life, and don’t want to do it alone. Thank you to everyone who participated, to those who organized their own local event, and to everyone who joined in online. Let’s take a look at some of what went on.

Nigeria’s power grid is not reliable and waiting around isn’t going to make the problem any better. The gathering in Lagos spent World Create Day talking about ways to overcome power grid problems and improve access to electricity for everyone.

Cape Town, South Africa had a huge turnout! They had speakers, lightning talks, project presentations, and broke into smaller groups to brainstorm ideas.

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