The Fine Art Of Acid Etching Brass

February 17, 2018 by 17 Comments

If you were building a recreation of the James Watt micrometer, where would you start? If you’re [rasp], the answer would be: “Spend a year trying to find the best way to make etched brass discs.” Luckily for us, he’s ready to share that information with the rest of the world. While it’s rather unlikely anyone else is working on this specific project, the methods he details for getting museum-quality results on brass are absolutely fascinating.

The process starts with sanding down the bare brass and applying a layer of clear packing tape to the metal. [rasp] then covers the piece with LaserTape, which is a special tape designed to make laser-cut masks for sandblasting. But the masking principle works just as well for painting or chemical etching.

With the LaserTape in place, the piece is then put into the laser and the mask is cut out. Once cut, there’s the tedious task of peeling off all the cut pieces of tape, which [rasp] does with a dental pick. Once the pieces are pulled off, the brass is ready for its acid bath.

Anyone who’s etched their own PCB with ferric chloride will recognize these next steps. The piece is put into the acid bath and agitated every 10 minutes or so. It’s interesting to note that [rasp] places the piece in the bath upside-down, using little 3D printed “feet” to suspend the brass sheet off the bottom of the container. This allows the debris from the etching process to fall down and away from the piece. After about an hour out in the sun, the piece is pulled out of the bath and carefully washed off.

Once clean off, the piece is sprayed with black spray paint to darken up the etched areas. The moment of truth comes when the paint has dried and the layers of tape are carefully peeled back to reveal the etching. [rasp] then wet sands the piece with 1000 and 2000 grit paper, and a final pass with polishing compound brighten up the surface to a mirror-like shine. It’s quite a bit of manual labor, but the end result really is spectacular.

In the video after the break, [rasp] breaks down the entire process, including the additional machine work required to turn these brass plates into functional components of the final machine. As an added bonus, he even includes a lot of his failed attempts in an effort to keep others from making the same mistakes. Something we love to see here at Hackaday.

The process used here is similar to the snazzy brass name plates we showed earlier in the year, and has even been done without a laser using photoresist.

[via /r/DIY]

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Great Beginnings For Vintage Computing In Seattle; VCF PNW

February 17, 2018 by 27 Comments

The pitch to my wife was simple: “Feel like spending the weekend in Seattle?” That’s how I ended up at the inaugural Vintage Computer Festival Pacific Northwest last weekend, and I’m glad we made the five-hour drive into The Big City to check it out. Hackaday is a VCF sponsor, after all, so it seemed like a great excuse to make the trip. That it ended up being two consecutive days of great Seattle weather was only icing on the cake of being able to spend time with fellow retro computer aficionados and their dearest bits of old hardware, in a great museum dedicated to keeping computer history alive and accessible.

The fact that Seattle, home of Microsoft, Amazon, and dozens of other tech companies, has until now been left out of the loop in favor of VCF East in New Jersey and VCF West in Mountain View seems strange, but judging by the reception, VCF PNW is here to stay and poised to grow. There were 20 exhibitors for this go around, showing off everything from reanimated PDP-11 and Altair 8800 control panels to TRS-80s from Model 1 through to the CoCo. Almost every class of reasonably transportable retro hardware was represented, as well as some that pushed the portability envelope, like a working PDP-8 and a huge Symbolics 3640 LISP workstation.

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This Boxing Bell Is A Trip

February 17, 2018 by 8 Comments

[MeasuredWorkshop] wanted to know how a boxing bell mechanism worked. The best way to learn is by doing, so he jumped right in and built one! Boxing bells are a rare surviving example of the trip bell mechanism. Trip bells were used in schools and public buildings as fire alarms. They’ve since been replaced by modern electric systems.

The mechanical linkage behind the trip bell is a one-way lever. This is the arm you pull on. It has a hinged section which stays rigid when the arm is pulled down, but rotates away when the arm is released. [Measured Workshop] built the mechanics of his bell using rather basic tools. The brunt of the work was handled by an angle grinder and a drill press.

The sounder for this boxing bell came from an old school bell. The industrial grey paint was chemically stripped, and the metal cleaned up for a nice brushed finish. The metal stands out nicely against the wood board [Measured Workshop] used as a base.

The finished product looks and sounds the part – now he just has to find a boxing gym in need of a bell!

We’re really becoming fond of the “wordless workshop” style videos that have been popping up on YouTube. [Jimmy DiResta] has been doing it for years, and relative newcomers [HandToolRescue] and [Measured Workshop] are both producing some great content!

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Catching The (PCIe) Bus

February 17, 2018 by 24 Comments

If you are trying to learn about FPGAs, there is only so far you can go with the usual blinking lights and VGA outputs. Eventually, you want to do something more. Although not terribly cheap, you can get FPGA boards in a PCIe form-factor and use them directly with PC software. Is it easy? Well, it isn’t flashing an LED, but there are tools to help. [Angelos Kyriakos] did a Master’s thesis on the very subject and used a project known as RIFFA to help with the task.

RIFFA (Reusable Integration Framework for FPGA Accelerators) is a simple framework for communicating data from a host CPU to an FPGA via a PCI Express bus. The framework requires a PCIe enabled workstation and an FPGA on a board with a PCIe connector. RIFFA supports Windows and Linux, Altera and Xilinx, with bindings for C/C++, Python, MATLAB, and Java. With proper design, RIFFA can transfer quite a bit of data in a short period of time between your computer and your FPGA.

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Resurrecting An Amiga CD32

February 16, 2018 by 15 Comments

As an editor on Amiga magazines in a previous life, this is kind of bittersweet. [RetroManCave] was donated an Amiga CD32 games system, and it is trying to resurrect it. If you’ve not heard of it, the CD32 was a 1993 games console based on the Amiga home computer system. It was the last gasp for Commodore, the beleaguered company behind the Amiga. In this first video of a series, they take the system apart, take you through what’s inside and boot it up. The system boots, but there is some sort of problem with the video sync, and they will be taking a closer look at fixing that next. We have featured a couple of similar projects from [RetroManCave] before, such as their brain transplant on a Big Trak toy and Commodore 64 fix. This video (after the break) is worth a watch if you are curious about old systems like this, want some tips on resurrecting old hardware or just want to shed a tear as your misspent youth is torn apart before your eyes.

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Underwater Logging For Science

February 16, 2018 by 8 Comments

Logging data with an Arduino is old-hat for most Hackaday readers. However, [Patricia Beddows] and [Edward Mallon] had some pretty daunting requirements. Their sensors were going underground and underwater as part of an effort to study conditions underwater and in caves. They needed to be accessible, yet rugged. They didn’t want to use batteries that would be difficult to take on airplanes, but also wanted more than a year of run time. You can buy all that, of course, if you are willing to pay the price.

Instead, they used off-the-shelf Arduino boards connected together inside PVC housings. Three alkaline AA batteries are compact and give them more than a year of run time. They wrote a journal paper to help other scientists use the same techniques for the Sensors journal published by the Multidisciplinary Digital Publishing Institute.

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Analyzing Hobby Motors With An Oscilloscope

February 16, 2018 by 20 Comments

We always like finding new excuses reasons to use our test equipment, so we couldn’t help but be intrigued by this tip from [Joe Mosfet]. He uses the ever-popular Rigol DS1054Z to demonstrate the differences between a handful of brushless motors when rotated by his handheld drill at a constant RPM. Not only is he able to identify a blown motor, but it allows him to visualize their specifications which can otherwise seem a bit mystifying.

One wire from each motor is used as the ground, and channels one and two are connected to the remaining wires. Despite the DS1054Z having four channels, [Joe] is actually only using two of them here. The third channel being displayed is a virtual channel created by a math function on the scope.

After wiring them up, each motor got put into the chuck of his drill and spun up to 1430 RPM. The resulting waveforms were captured, and [Joe] walks us through each one explaining what we’re seeing on the scope.

The bad motor is easy to identify: the phases are out of alignment and in general the output looks erratic. Between the good motors, the higher the Kv rating of the motor, the lower voltage is seen on the scope. That’s because Kv in the context of brushless motors is a measurement of how fast the motor will spin for each volt. The inverse is also true, and [Joe] explains that if he could spin his 2450Kv motor at exactly 2450 RPM, we should see one volt output.

Beyond demonstrating the practical side of Kv ratings, [Joe] also theorizes that the shape of the wave might offer a glimpse into the quality of the motor’s construction. He notes his higher end motors generate a nice clean sine wave, while his cheaper ones show distortion at the peaks. An interesting note, though he does stress he can’t confirm there’s a real-world performance impact.

Last year we featured a similar method for identifying bad brushless motors using a drill press and an oscilloscope, but we liked that [Joe] went through the trouble of testing multiple motors and explaining the differences in their output.

[via /r/multicopter]