How to Fail at Laser Cutting

Laser cutters are CNC power tools, which means an operator uploads a job digitally and then pushes START to let the machine do all the work while they lie back in a hammock sipping a margarita, occasionally leaping out in a panic because the sound coming from the machine changed slightly.

Like other power tools, laser cutters are built around doing one thing very well, but they require an operator’s full attention and support. The operator needs to handle all the other things that go on before, during, and after the job. It’s not too hard to get adequate results, but to get truly professional and repeatable ones takes work and experience and an attention to detail.

People often focus on success stories, but learning from failures is much more educational. In the spirit of exploring that idea, here are my favorite ways to fail at laser cutting and engraving. Not all of these are my own personal experience, but they are all someone’s personal experience.

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How to Design, Manufacture, and Document a Hardware Product

It’s pretty awesome to have a hardware design hero jump at the chance to work on a Hackaday conference badge. I am of course talking about Voja Antonic.

I’ve gotten to know him over the last two years when we were introduced and he agreed to work on some original articles. He’s long been a hacker and shared his story of technology despite politics and society changing around him. His Galaksija computer was the first personal computer available in Yugoslavia with over 8,000 kits sold. Since those days he never stopped refining his design and fabrication skills. For instance, his method of making cases from FR4 is beyond compare, and reading some of his wisdom from hardware design in the casino industry is the kind of fascinating stuff that rarely makes it out for others to enjoy.

But I digress — the point is Voja’s been around the block, he knows what he’s doing, and he does it at an amazingly high level. He did an incredible job with the Hackaday | Belgrade conference badge. It features a 16×8 LED display, IR comms hardware, 5 user buttons, USB programming, an option for an accelerometer module, and has spectacular life running on two AAA batteries. It was a hit at the conference, and so was his talk discussing the design and fabrication. Check it out below and then join me below the fold.

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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.

How To Know When An Accelerator Is Not Right For Your Startup

A few weeks ago we ran an article on the benefits of accelerator programs. While I agreed with almost everything in it, the article still bothered me, and I wanted to start a discussion about when an accelerator is not appropriate. So many startups are regularly asked “have you thought about Kickstarter? Shark Tank? Are you raising money? YCombinator?” These questions are constantly ingrained into people’s brains and they come to think those are the only options.

The reality is that there are lots of ways to build a company, and Kickstarter, Shark Tank, angel investors, and accelerators are all new within the last few years, and they aren’t right for many people. So let’s look at when an accelerator is right for you.

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Bunnie’s Guide to Shenzhen Electronics

[Bunnie Huang] is now officially the person who wrote the book on electronics manufacturing in Shenzhen, China. His Crowd Supply campaign for The Essential Guide to Electronics in Shenzhen has blown way past the initial goal. [Bunnie] is the first person who comes to mind for anyone needing help getting their electronics built in the region.

The books is meant as a travel companion. Hackaday was in China last June and toured the markets of Hua Qiang Bei. They are incredibly overwhelming, but people are very nice, willing to help, and none of them speak English. [Bunnie’s] approach is pages with squares you can point to in order to express your meaning. Standing at the capacitor stall? There’s a page for that. Gawking at a booth packed full of LEDs and need them in reels instead of tape? That’s in the book too. Even better, this isn’t a one-way thing. You should be able to understand well enough what they vendor is trying to convey as they point at the pages to answer your questions. This is certainly better than our method of trying to find pictures of addresses and Chinese characters on our phones. Everything is at the ready.

It doesn’t end there. The images of the book’s table of contents shows that you’ll get help with getting into the country, getting around once you’re there, and making the deal when you do find what you need. If you’re ever going to make the trip to Shenzhen, this is the first thing you should put in your backpack.

Since you’re already in the mood to purchase something made of paper, we think you’ll be interested you in this gorgeous Hackaday Omnibus Vol 02. It’s 128 pages of the best original content published on Hackaday over the past year, including the stunning artwork of Joe Kim.

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Building One Thing In China

Conventional wisdom dictates that if you need to make a million of something, you go to China. China is all about manufacturing, and there aren’t many other places on the planet that have the industry and government-subsidized shipping that will bring your product from China to people around the world. Building a million things in China is one thing, but what about building one thing? How do you create a working prototype of your latest product, and how do you make that prototype look like something that isn’t held together with zip ties and hot glue? The folks at Hatch Manufacturing have a guide for doing just that, and lucky for us, it’s a process that’s easy to replicate in any well-equipped shop.

In this tutorial/case study/PR blitz, Hatch Manufacturing takes on constructing a one-off smartphone. The Huaqiangbei markets in Shenzhen are filled with vendors selling smartphones of all shapes and sizes. If you want a miniature iPhone running Android, that’s no problem. If you want a phone that looks like a 1969 Dodge Charger with the Stars and Bars on top, you can find it in China. But how are all these phones made, and how do you show off a prototype to factories begging for business?

The answer, as is always the case, comes from one-off manufacturing. Building, assembling and reworking PCBs is a well-trodden path whose process could fill several volumes, but for this post, Hatch Manufacturing decided to focus on the plastics that go into a smartphone or tablet.

Once the case or enclosure is designed with a few CAD tools, a block of plastic is run through a mill. After that, it’s a matter of painting and finishing the latest smartphone that will show up in the Chinese market. Putting a professional finish on a block of plastic is something that will look familiar to anyone who has ever assembled a miniature plastic model. There’s priming, airbrushing, sanding, more painting, sanding, wet sanding, and still more sanding. After that comes polishing the plastic part to a fine finish. It is extraordinarily labor intensive work even for a skilled hand with the right equipment.

Once the plastics are done, the PCB, display, battery, and everything else comes together in a completely custom one-off prototype. It’s very similar to how this would be done in any small shop with a benchtop mill and a dozen grades of wet/dry sandpaper. It’s also something anyone can do, provided they have enough practice and patience.

What’s in a tool? A case for Made in USA.

A lot of people make the argument that you can’t go wrong buying a tool made in USA, Germany, Japan, Switzerland, etc. They swear that any Chinese tool will be garbage and it’s not worth purchasing them. Now, any discerning mind will say, “Wait a minute, why? China has a huge economy, experienced people, and the ability to use all the scary chemicals that make the best steel. Why would their tools be any better or worse than ours?” It’s a very valid argument. There are lots of Chinese tools that are the best in the world. Most of what we see in our stores are not. So what is the difference. Why does a country who can make the best tools not make the best tools? Surely it isn’t purely cost cutting. Is it cultural? The opinion I wish to put forth is that it’s a matter of design intent communication.

I’ve worked as an engineer in industry. The one common thread between a quality product and a bad product has always been this, ”Is the person who designed the product involved in making the product?” If the person or peoples who imbued the design intent into the original product are actively involved in and working towards the execution of that product, that product has a vastly greater chance of being good. Or in other words: outsourcing doesn’t produce a bad product because the new people making the product don’t care. It makes a bad product because the people who understand the intent behind the product are separated from its execution.

As you can see the export made crescent wrench is not made to the same tolerances as the previous wrench.
As you can see the export made crescent wrench is not made to the same tolerances as the previous wrench.

Let’s take the Crescent wrench as an example. Crescent wrenches used to be made in USA. In the past few years they have begun to make them in China. We can spot many visual differences right away. The new Crescent wrench has a different shape, the logo has changed and the stamping for the logo is dodgy, and worse, the tool just doesn’t operate as well as it used to. The jaws aren’t as hard and they wiggle more. What happened? How could Crescent mess up their flagship so badly. Surely they intended just to cut costs, not to reduce quality. This isn’t shameful in itself

What happened to the Crescent wrench is easily explained by anyone who has seen a product from design to execution before. A factory in the USA set out to make a good adjustable wrench. Hundreds of engineers and employees worked in a building to make a good wrench. When their machines didn’t work, they came up with solutions. When their quality was lacking, they implemented better processes. They had a list of trusted suppliers. They could guarantee that the materials that came in would be imbued with their vision and intent when the product came out. The intent and will of all those people built up in one place over time.

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