Bad Idea For Desoldering Actually Might Be Pretty Smart

January 6, 2021 by 49 Comments

This video on building a DIY desoldering iron says it all right up front: this is stupid and dangerous, and you shouldn’t do it. But that doesn’t mean it doesn’t work, or that it doesn’t have potential to be turned into something else.

The story begins, as it often does these days, on the pages of Amazon as [AnotherMaker] shopped for a real desoldering setup. Despite a case of sticker shock, he took the plunge on a nice Hakko vacuum desolderer, but as is also often the case, it failed to arrive. Rather than accept defeat, [AnotherMaker] purchased a cheap-o soldering iron and a brass tee fitting for small-bore tubing that would chuck nicely into the spot where the stock tip once lived, giving him a way to both melt solder and move air.

Unfortunately, rather than applying a vacuum, he chose to blast 100 PSI compressed air through the tip, which certainly moves a lot of solder, perhaps at the cost of burns and eye injuries. The potential for accidental short circuits is pretty high too, but c’mon — it’s not like we all haven’t flicked or dropped a board to desolder something. Is this really much different?

As fraught with peril as this method may be, [AnotherMaker] is onto something here. Perhaps adding a 3D-printed venturi generator could turn that blast of air into a vacuum. Or maybe a vacuum pump for a manual pick-and-place would do the trick too.

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Amazon’s Custom T-Shirt May Rub You The Wrong Way

January 6, 2021 by 49 Comments

How far would you go in pursuit of the perfect black t-shirt? Would you let Amazon build a virtual double of your body? They already know so much about you, so what’s a body scan or two between customer and company?

So here’s the deal — Amazon is trying to launch a brand of bespoke clothing called Made for You, and they’re starting with custom solid color t-shirts. Here’s how it works: you give them $25 along with information about your height, weight, and skin tone. Then you upload two pictures of your torso to their app, and these get turned into a 3D model of your body. Once your avatar is built to match, you design your shirt to fit the model. In theory, you get a really good idea of how it will fit.

You can choose from two different fabrics and eight colors, and can customize the neckline, the shirt length, and the sleeve length. If you want to, you can put your name on the tag. Then your perfect t-shirt gets made in the US from imported fabric — either lightweight or medium weight pima cotton. We’re not sure if robots or people are making them, but our money is on people. After all, Amazon is the company that created Mechanical Turk to form a pool of humans available to do on-demand work via the Internet. This is along those lines but with tailors sewing to your specifications. The big questions are what do you get, how does the technology make these better than off-the-rack, and do you give up your privacy in return?

One-Size Fits One

To say that these are custom t-shirts is a bit of a stretch. Oh you don’t need to worry about the t-shirts being skin-tight and showcasing your spare tire — if it’s a relaxed fit you want, that’s one of the options. But the current options are limited.

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Heat Turns 3D Printer Filament Into Springs

January 6, 2021 by 11 Comments

The next time you find yourself in need of some large-ish plastic springs, maybe consider [PattysLab]’s method for making plastic springs out of spare filament. The basic process is simple: tightly wind some 3D printer filament around a steel rod, secure it and wrap it in kapton tape, then heat it up. After cooling, one is left with a reasonably functional spring, apparently with all the advantages of annealed plastic.

The basic process may be simple, but [PattysLab] has a number of tips for getting best results. The first is to use a 3D-printed fixture to help anchor one end of filament to the steel rod, then use the help of an electric drill to wind the filament tightly. After wrapping the plastic with kapton tape (wrap counter to the direction of the spring winding, so that peeling the tape later doesn’t pull the spring apart), he suspends it in a pre-heated oven at 120 C for PLA and 160 C for PETG. How long does it stay in there? [PattysLab] uses the following method: when the spring is wound, he leaves a couple inches of filament sticking out to act as a visual indicator. When this segment of filament sags down, that’s his cue to begin the retrieval process. After cooling, the result is a compression or extension spring, depending on how it was wound before being heated.

[PattysLab] shared a short video on this Reddit post that shows both springs in action, and the process is all covered in the video, embedded below.

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Custom Controller Makes Turbomolecular Pump Suck

January 6, 2021 by 16 Comments

[Mark Aren] purchased a pair of Turbomolecular pumps (TMP) sans controllers, and then built an FPGA based BLDC controller for the Turbomolecular pumps. A TMP is similar to a jet turbine, consisting of several stages of alternating moving turbine blades and stationary stator blades, and having turbine rotation speeds ranging from 10,000 rpm to 90,000 rpm. TMP’s cannot exhaust directly to atmosphere, and must be combined with a backing (or roughing) pump to create a lower grade vacuum first. They find use in lots of applications such as electron microscopy, analytical sciences, semiconductors and lamp manufacturing. With the lamp industry rapidly embracing LEDs, many of the traditional lamp making lines are getting decommissioned, and if you are lucky, you can snag a TMP at a low cost – but it still will not be cheap by any means.

The two BOC-Edwards EXT255H Compound Molecular Pumps (PDF), that [Mark] bought did not have their accompanying EXC100E Turbomolecular Pump Controllers (PDF), and given pandemic related restrictions, he decided to build a controller of his own, using components and modules from his parts bin. The pump and controller user manuals offered only sketchy details about the sensored BLDC motor used in the pump. The low phase-to-phase resistance implied low drive voltage, and [Mark] decided to try running it at 24 V to start with. He already had experience using the Mitsubishi PS21245-E IGBT inverter bridge, and even though it was rated for much higher voltages, he knew that it would work just fine at 24 V too.

After figuring out a state machine for motor commutation that utilized PWM based adjustable current control, he implemented it on a 128 element FPGA board. Considering how expensive the TMP was, he wisely decided to first try out his driver on a smaller “expendable” BLDC motor. This whole process was non-trivial, since his available IGBT module was untested and undocumented, and required several tweaks before he could run it at the required 12 kHz PWM signals. His test motor was also undocumented, failing to run correctly when first hooked up. Fixing that issue meant having to disassemble the motor to check its internal wiring. Eventually, his efforts paid off, and he was able to safely run the TMP motor to confirm that his design worked.

With FPGA code, IGBT wiring and power supply issues sorted, the next step was to add a supervisory micro-controller, using an Arduino Nano. Its functions included interfacing with a touch screen LCD as a user interface, communicating with the FPGA module, and controlling several relays to switch power to the motor power supply, the roughing pump, TMP cooling fan, and a solenoid for the vacuum vent. Spindle current is calculated by measuring voltage drop across shunt resistors on the low side of the IGBT. Motor speed is measured using one of the motor hall sensors, and a thermistor provides motor temperature sensing. [Mark]’s PCB fabrication technique seems a bit different too. Using an Excellon drill file, he drills holes in a piece of plastic using a laser cutter to create a bare board, and then solders copper tracks by hand.

His initial tests at atmospheric pressure (although not recommended unless you monitor pump temperature), resulted in 7300 rpm while consuming about 7 Amps before he had to shut it down. In further tests, after adding a roughing pump to the test setup, he was able to spin the TMP to 20,000 rpm while it consumed 0.6 A. Obviously, the pump is rated to operate at a higher voltage, possibly 48 V based on the values mentioned in the TMP controller manual. The project is still “work in progress” as [Mark] hopes to eventually drive the pump up to its specified 60,000 rpm operating speed. What is not clear is what he eventually intends to do with this piece of exotic machinery. All he mentions is that “he has recently taken an interest in high-vacuum systems and is interested in exploring the high-vacuum world of electron guns.”

Maybe [Mark] can compare notes with the Open Source Turbomolecular Pump Controller that we featured some time back. And if you’d like to be a little bit more adventurous and build you own TMP, we got you covered with this DIY Everyman’s Turbomolecular Pump.

Xbox Controller Mod Gets Serious About Stick Drift

January 5, 2021 by 47 Comments

Many a gamer has found that after a few years of racing around the track or sending demons back from whence they came, the analog sticks on their trusty controller can start to drift around. Many times it’s a fairly minor problem, something you might only notice if you were really keeping an eye out for it, but it can definitely be annoying. Those handy with a soldering iron might just swap out the sticks for replacements once it gets to that point, but [Taylor Burley] wondered how difficult it would be to recalibrate the ailing sticks instead.

To be clear, [Taylor] acknowledges this approach is overkill. It would be cheaper and easier to just replace the drifting stick with a new one. Even if you take into account that new sticks might not be as high quality as the originals and could give up the ghost faster, this probably isn’t worth the effort. But that doesn’t mean it’s not an interesting hack.

In the video after the break, [Taylor] starts by explaining how stick drift occurs in the first place. Each axis of the stick is physically connected to the wiper of a potentiometer, so for 10K pots, the stick’s center point should correspond to a resistance of 5K. He then goes on to measure the resistance in a bad joystick, and sure enough, the center resistance is off by several hundred Ohms.

To fix this, he comes up with a simple circuit that places additional potentiometers between the wipers. With two joysticks and two adjustment pots per axis, that makes eight little adjustment wheels that need to be fiddled with to get the center points calibrated properly. In this case [Taylor] uses a controller diagnostic tool for the Xbox to quantify the impact his adjustments are making so he can dial it in perfectly, but the idea is the same no matter who’s logo is on the box.

We’d say this is the most overkill attempt at addressing the issue of stick drift on gaming controllers we’ve ever seen, but that title has to go to [Matteo Pisani], who replaced the analog stick on his Switch Joy-Con with a custom circular touchpad.

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AI On The Highway

January 5, 2021 by 13 Comments

A couple of announcements caught our attention last week regarding AI-controlled cars. South Korea’s Kakao Mobility and local startup Autonomous A2G launched a limited self-driving taxi service in Sejong City this month, made possible by enabling legislation passed in May. For now, the service is restricted to government employees, and the AI driver will be backed-up by an engineer who is there to monitor the systems and take over in an emergency. The companies plan to expand the fleet and service areas this year, although no details are given.

Another announcement comes from the Ministry of Land, Infrastructure and Transport about the on-going successes of the semi-autonomous truck platooning program. This is a collaboration between the Korean Expressway Corporation, Kookmin University in Seoul, and Hyundai Motors. Previously restricted to a designated test road called the Yeoju Smart Highway, the program is now being tested on public roads at speeds up to 70 kph. This year the program will expand to platoons of 4 trucks running at 90 kph. We’ve always thought that long-haul trucking and freight industries would be an early adaptor AI technologies, and one which AI could offer significant benefits.

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Burned Out SKR E3 Mini Gets New Stepper Driver

January 5, 2021 by 19 Comments

It didn’t take long to figure out that a dead X axis and an message saying “TMC CONNECTION ERROR” meant that one of the stepper drivers on the SKR E3 Mini 3D printer control board had released the magic smoke. Manufacturer BigTreeTech replaced the board under warranty, and the printer was back up and running in short order. But instead of tossing it in the trash, [Simon] wondered how hard it would be to repair the dead board.

Removing the original stepper driver IC.

The short answer is, not very hard. There was no question as to which of the four TMC2209 drivers was shot, since the X motor was the only one experiencing a problem. The drivers unfortunately aren’t socketed on this board, but after a little kiss with the hot air, the old chip was off.

[Simon] didn’t have any spare TMC2209 chips, but the TMC2208 has the same pinout and is a drop-in replacement. The TMC2208 is rated for a bit less current, but it shouldn’t be a problem under normal circumstances.

Other than the stepper connector getting a little toasty during the installation, the swap went off without a hitch and the board was up and running again. [Simon] ended up putting the now repaired SKR E3 Mini in his Ender 3; a nice 32-bit upgrade compared to the ATmega1284 that was originally running the show. Though in the past, he’s managed to squeeze a bit more performance out of the older 8-bit board as well.