Books You Should Read: Poorly Made In China

This book is scary, and honestly I can’t decide if I should recommend it or not. It’s not a guide, it doesn’t offer solutions, and it’s full of so many cautionary tales and descriptions of tricks and scams that you will wonder how any business gets done in China at all. If you are looking for a reason not to manufacture in China, then this is the book for you.

The author is not involved in the electronics industry. Most of the book describes a single customer in the personal products field (soap, shampoo, lotions, creams, etc.). He does describe other industries, and says that in general most factories in any industry will try the same tricks, and confirms this with experiences from other similar people in his position as local intermediary for foreign importers.

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The Mystery Behind the Globs of Epoxy

When Sparkfun visited the factory that makes their multimeters and photographed a mysterious industrial process.

We all know that the little black globs on electronics has a semiconductor of some sort hiding beneath, but the process is one that’s not really explored much in the home shop.  The basic story being that, for various reasons , there is no cheaper way to get a chip on a board than to use the aptly named chip-on-board or COB process. Without the expense of encapsulating  the raw chunk of etched and plated silicon, the semiconductor retailer can sell the chip for pennies. It’s also a great way to accept delivery of custom silicon or place a grouping of chips closely together while maintaining a cheap, reliable, and low-profile package.

As SparkFun reveals, the story begins with a tray of silicon wafers. A person epoxies the wafer with some conductive glue to its place on the board. Surprisingly, alignment isn’t critical. The epoxy dries and then the circuit board is taken to a, “semi-automatic thermosonic wire bonding machine,” and slotted into a fixture at its base. The awesomely named machine needs the operator to find the center of the first two pads to be bonded with wire. Using this information it quickly bonds the pads on the silicon wafer to the  board — a process you’ll find satisfying in the clip below.

The final step is to place the familiar black blob of epoxy over the assembly and bake the board at the temperature the recipe in the datasheet demands. It’s a common manufacturing process that saves more money than coloring a multimeter anything other than yellow.

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Filling The Automation Gap In Garment Manufacturing

Even in this age of wearable technology, the actual fabric in our t-shirts and clothes may still be the most high-tech product we wear. From the genetically engineered cotton seed, though an autonomous machine world, this product is manufactured in one of the world’s largest automation bubbles. Self-driving cotton pickers harvest and preprocess the cotton. More machines blend the raw material, comb it, twist and spin it into yarn, and finally, a weaving machine outputs sheets of spotless cotton jersey. The degree of automation could not be higher. Except for the laboratories, where seeds, cotton fibers, and yarns are tested to meet tight specifications, woven fabrics originate from a mostly human-free zone that is governed by technology and economics.

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Lessons in Small Scale Manufacturing From The Othermill Shop Floor

Othermachine Co. is not a big company. Their flagship product, the Othermill, is made in small, careful batches. As we’ve seen with other small hardware companies, the manufacturing process can make or break the company. While we toured their factory in Berkeley California, a few interesting things stood out to us about their process which showed their manufacturing competence.

It’s not often that small companies share the secrets of their shop floor. Many of us have dreams of selling kits, so any lessons that can be learned from those who have come before is valuable. The goal of any manufacturing process optimization is to reduce cost while simultaneously maintaining or increasing quality. Despite what cynics would like to believe, this is often entirely possible and often embarrassingly easy to accomplish.

Lean manufacturing defines seven wastes that can be optimized out of a process.

  1. Overproduction: Simply, making more than you currently have demand for. This is a really common mistake for first time producers.
  2. Inventory: Storing more than you need to meet production or demand. Nearly every company I’ve worked for has this problem. There is an art to having just enough. Don’t buy one bulk order of 3,000 screws for six months, order 500 screws every month as needed.
  3. Waiting: Having significant delays between processes. These are things ranging from running out of USB cables to simply having to wait too long for something to arrive on a conveyor belt. Do everything you can to make sure the process is always flowing from one step to another.
  4. Motion: If you have a person walking back and forth between the ends of the factory to complete one step of the manufacturing process, this is wasted motion.
  5. Transport: Different from motion, this is waste in moving the products of each individual process between sections of the assembly.
  6. Rework: Get it right the first time. If your process can’t produce a product that meets specifications, fix the process.
  7. Over-processing: Don’t do more work than is necessary. If your part specifies 1000 hours of runtime don’t buy a million dollar machine to get 2000 hours out of it. If you can find a way to do it with one step, don’t do it with three.


The first thing that stuck out to me upon entering Othermachine Co’s shop floor is their meticulous system for getting small batches through the factory in a timely manner. This allows them to scale their production as their demand fluctuates. CNCs and 3D printers are definitely seasonal purchases; with sales often increasing in the winter months when hackers are no longer lured away from their workstations by nice weather.

As the seven sins proclaim. It would be a bad move for Othermachine Co. to make too many mills. Let’s say they had made an extra 100 mills while demand was at a seasonal low. If they found a design or quality problem from customer feedback they’d have to commit to rework, potentially throwing away piles of defective parts. If they want to push a change to the machine or release a new model they’d either have to rework the machines, trash them, or wait till they all sold before improving their product. Even worse, they may find themselves twiddling their thumbs waiting for their supply to decrease enough to start manufacturing again. This deprives them of opportunities to improve their process and leads to a lax work environment.

One way to ensure that parts are properly handled and inventory is kept to a minimum is with proper visual controls. To this end, Othermachine Co has custom cardboard bins made that perfectly cradle all the precision parts for each process in their own color coded container. Since the shop floor is quite small, it lets them focus on making spindle assemblies one day and motion assemblies another without having to waste time between each step. Also, someone can rekit the parts for a recently completed step easily without interrupting work on the current process going on.


It’s hard to define what’s over processing and what isn’t. My favorite example of what isnt, and something I’ve fought for on nearly every factory floor I’ve worked on is proper torque limiting screwdrivers. They’re a little expensive, but they are a wonderful tool that helps to avoid costly rework and over processing. For example, let’s say you didn’t have a torque limiting screwdriver. Maybe your customers would complain that occasionally a screw came loose. Now, one way to solve this would be the liberal application of Loctite. Another way would be an additional inspection step. Both of these are additional and completely uneccessary steps as most screws will hold as long as they are torqued properly.

In one factory I worked in, it was often a problem that a recently hired worker would overtorque a screw, either stripping it or damaging the parts it was mating together. A torque limiting screwdriver takes the worker’s physical strength out of the equation, while reducing their fatigue throughout the day. It’s a win/win. Any time a crucial step can go from unknown to trusted with the application of a proper tool or test step it is worth it.

Another section where Othermachine Co. applied this principle is with the final machining step for the CNC bed. The step produces a large amount of waste chips. Rather than having an employee waste time vacuuming out every Othermill after it has gone through this process, they spent some time designing a custom vacuum attachment. This essentially removed an entire production step. Not bad!

IMG_0396 (2)

With the proper management of waste it is entirely possible to save money and improve a process at the same time. It takes a bit of training to learn how to see it. It helps to have an experienced person around in order to learn how to properly respond to them, but with a bit of practice it becomes a skill that spreads to all areas of life. Have any of you had experience with this kind of problem solving? I’ve really enjoyed learning from the work stories posted in the comments.

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.