Adorable Desktop Disc Sander Warms Our Hearts And Our Parts

December 4, 2018 by Kerry Scharfglass 17 Comments

Casually browsing YouTube for “shop improvements” yields a veritable river of project ideas, objects for cat amusement, and 12 INCREDIBLE SHOP HACKS YOU WON’T BELIEVE, though some of these are of predictably dubious value. So you might imagine that when we found [Henrique]’s adorable disc sander we dismissed it out of hand, how useful could such a tiny tool be? But then we remembered the jumbo tub o’ motors on the shelf and reconsidered, maybe a palm sized sander has a place in the tiny shop.

Electrically the build is a simple as can be. It’s just a brushed DC motor plugged into a wall wart with a barrel jack and a toggle switch. But what else does it need? This isn’t a precision machine tool, so applying the “make it out of whatever scrap” mindset seems like a much better fit than figuring out PWM control with a MOSFET and a microcontroller.

There are a couple of neat tricks in the build here. The most obvious is the classic laser-cut living hinge that we love so much. [Henrique] mentions that he buys MDF in 3 mm sheets for easy storage, so each section of the frame is built from layers that he laminates with glue himself. This trades precision and adds steps, but also give him a little flexibility. It’s certainly easier to add layers of thin stock together than it would be to carve out thicker pieces. Using the laser to precisely cut holes which are then match drilled through into the rest of the frame is a nice build acceleration too. The only improvement we can imagine would be using a shaft with a small finger chuck (like a Dremel) so it could use standard rotary tool bits to avoid making sanding disks by hand.

What could a tool like this be used for? There are lots of parts with small enough features to be cleaned up by such a small tool. Perhaps those nasty burrs after cutting off a bolt? Or trimming down mousebites on the edges of PCBs? (Though make sure to use proper respiration for cutting fiberglass!)

If you want to make one of these tools for your own desk, the files are here on Thingiverse. And check out the video overview after the break.

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Keep Both Hands On The Probes With This Oscilloscope Footswitch

December 2, 2018 by Dan Maloney 18 Comments

We’ve got two hands, so it’s natural to want to use both of them while diagnosing a circuit with an oscilloscope. Trouble is, keeping both hands on the probes makes it a touch difficult to manipulate the scope. If only there were some way to put your idle lower appendages to work.

This multipurpose oscilloscope footswitch interface makes so much sense that we wonder why such a thing isn’t standard equipment on more scopes. [Paul Roukema]’s interface relies on the USB Test and Measurement Class (USBTMC) protocol that allows most modern scopes to be remotely controlled, somewhat like the General Purpose Interface Bus (GPIB) protocol of old. [Paul]’s interface uses an STM32 microcontroller to talk USBTMC to either Keysight’s Infinium scopes or the Tektronix DPO line, since those were what he had to test against. Tapping the footswitch cycles the acquisition mode on and off or triggers a single acquisition. He’s thoughtfully included the USBTMC specs in his GitHub project, so adapting it to other scopes should be straightforward. We’d even wager that older scopes with GPIB could enjoy the same handsfree control.

Have a down-market scope but still want to go handsfree? [Jenny List]’s primer on running a Rigol with Python might offer some hints on where to start.

CNC Machine Most Satisfyingly Mills Double-Sided PCBs

December 2, 2018 by Dan Maloney 50 Comments

We know that by this point in the development of CNC technology, nothing should amaze us. We’ve seen CNC machines perform feats of precision that shouldn’t be possible, whether it be milling a complex jet engine turbine blade or just squirting out hot plastic. But you’ve just got to watch this PCB milling CNC machine go through its paces!

The machine is from an outfit called WEGSTR, based in the Czech Republic. While it appears to be optimized for PCB milling and drilling, the company also shows it milling metals, wood, plastic, and even glass. The first video below shows the machine milling 0.1 mm traces in FR4; the scale of the operation only becomes apparent when a gigantic toothbrush enters the frame to clear away a little swarf. As if that weren’t enough, the machine then cuts traces on the other side of the board; vias created by filling drilled holes with copper rivets and peening them over with a mandrel and a few light hammer taps connect the two sides.

Prefer your boards with solder resist and silkscreening? Not a problem, at least judging by the second video, which shows a finished board getting coated with UV-cure resist and then having the machine mill away just the resist on the solder pads. We’re not sure how they deal with variations in board thickness or warping, but they sure have it dialed in. Regardless of how they optimized the process, it’s a pleasure to watch.

At about $2,600, these are not cheap machines, but they may make sense for someone needing high-quality boards with rapid turnaround. And who’s to say a DIY machine couldn’t do as good a job? We’ve seen plenty of them before, and covered the pros and cons of etching versus milling too.

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1,000 Watt Power Supply Tear Down And Repair

November 30, 2018 by Al Williams 7 Comments

[TheSignalPath] wanted to repair a broken Instek PSW80-40.5 because it has a lot of output for a programmable power supply — 1,080 watts, to be exact. This isn’t a cheap supply — it looks like it costs about $2,200 new. The unit wasn’t working and when he took it apart, he found a nasty surprise. There is a base PCB and three identical power supply modules, and virtually no access without disconnecting the boards. He continued the teardown, and you can see the results in the video below.

Each of the power supply modules are two separate PCBs and the design has to account for the high currents required. The power supply is a switching design with some filtering on the motherboard. One of the boards of the power supply module rectifies the incoming line voltage to a high DC voltage (about 400 volts). The second board then does DC to DC conversion to the desired output.

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Professional Results From Cheap Air Compressors

November 30, 2018 by Tom Nardi 21 Comments

The portable air compressors sold at big box hardware stores like Lowe’s and Home Depot are perfectly suited for the jobs they’re advertised for: namely throwing some nails into the wall or filling tires. But if you try to respray your car with that $50 Black Friday pancake air compressor, you’re going to have a bad day. The relatively small amount of air they hold is almost guaranteed to be contaminated with oil and moisture, making it unsuitable for painting or even just blowing the dust out of electronics.

But all is not lost. [Stephen Saville] has done an excellent job documenting his work to turn these low cost homeowner-grade air compressors into something suitable for spraying auto body panels. But even if you aren’t looking to put a sick pearlescent finish on the family minivan, these tips are worth checking out. From increasing the usable volume of air in the system to separating out contaminants, these modifications can unlock a whole new world of pneumatic projects.

The big one (literally and figuratively) is the swirl tube [Stephen] builds out of an old CO2 cylinder. The idea is that this will centrifugally clean the air, not unlike a cyclonic dust separator. As the air enters the top of the cylinder and spins around, contact with the cold metal will cause any moisture to condense out and collect down at the bottom. Oil and other particles in the air should also get spun out, leaving a central column of cleaner air. The collected water and contaminants at the bottom can be occasionally purged out by way of the cylinder’s original valve.

With a source of clean and dry air sorted, [Stephen] next wanted a way to get it around his shop. Using scrap metal pipes he puts together a system that not only gives him air where he needs it, but also increases the volume of compressed air he has available. By using large smooth metal pipes rather than something like flexible rubber hose, the plumbing puts very little resistance on air flow. The pipes therefore can be considered something of an extension of the compressor’s primary tank.

In the video after the break, [Stephen] shows off his new air system by laying down a very nice looking coat of paint on a car hood, but he also goes through the whole build process if you want to see the nuts and bolts of his system. He gives some great tips on welding and working with dissimilar metals which are worth the price of admission alone.

Outfitting the workshop with an integrated compressed air system sounds like the perfect second project to tackle once you’ve got the built-in dust collection system up and running.

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Reverse Engineering With Sandpaper

November 29, 2018 by Brian Benchoff 34 Comments

Every once in a while, and more so now than before, you’ll find a really neat chip with zero documentation. In [David]’s case, it’s a really cool USB 3.0 eMMC/ SD MMC controller. Use this chip, attach a USB port on one end, and some memory on the other, and you have a complete bridge. There are drivers, too. There are products shipping with this chip. The problem is, there is no data sheet. Wanting to use this chip, [David] turned to sandpaper to figure out the pinout of this chip.

The best example of a product that came with this chip is a simple board from the hardkernel store that happily came with fairly high resolution product photos. While waiting for these boards to be delivered, [David] traced the top layer of copper. This was enough to get an idea of what was going on, but the real work started when the boards arrived. These were placed in a flatbed scanner and carefully photographed.

The next step was to desolder all the parts, taking care to measure and catalog each component. Then, it’s off to sanding with 200 and 600 grit wet sandpaper. Slowly, the soldermask is removed and the top copper layer appears. After that, it’s just a matter of sanding and scanning, stacking all the layers together with your image processing software of choice.

There are a few caveats to hand-sanding a PCB to reverse-engineer the copper layers. First, it makes a mess. This is wet/dry sandpaper, though, and you can and should sand with water. Secondly, even pressure should be applied. We’re not sure if [David] was holding the sandpaper or not, but the best technique is to actually hold the board itself.

Despite a few problems, [David] did get the pictures of each copper layer. After assembling these images, he could make an Eagle part for an eMMC reader for his Nintendo Switch.

Overlooked Minimalism In Assistive Technology

November 23, 2018 by Brian McEvoy 27 Comments

If your eyes are 20/20, you probably do not spend much time thinking about prescription eyeglasses. It is easy to overlook that sort of thing, and we will not blame you. When we found this creation, it was over two years old, but we had not seen anything quite like it. The essence of the Bear Paw Assistive Eating Aid is a swiveling magnet atop a suction cup base. Simple right? You may already be thinking about how you could build or model that up in a weekend, and it would not be a big deal. The question is, could you make something like this if you had not seen it first?

Over-engineered inventions with lots of flexibility and room for expansion have their allure. When you first learn Arduino, every problem looks like a solution for that inexpensive demo board and one day you find yourself wearing an ATMEGA wristwatch. Honestly, we love those just as much but for an entirely different reason. When all the bells and whistles are gone, when there is nothing left but a robust creation that, “just works,” you have created something beautiful. Judging by the YouTube comments of the video, which can be seen below the break, those folks have no trouble overlooking the charm of this device since the word “beard” appears 95 times and one misspelling for a “bread” count of one. Hackaday readers are a higher caliber and should be able to appreciate its elegance.

The current high-tech solution for self-feeding is a robot arm, not unlike this one which is where our minds went when we heard about an invention about eating without using hands, and we will always be happy to talk about robot arms.

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