Remember the good old days when machines had a stout metal badge instead of cheap vinyl decals, and nameplates on motors were engraved in metal rather than printed on a label with a QR code? Neither do we, but these raised brass labels with color filled backgrounds look great, they’re surprisingly easy to make, and just the thing your gear needs to demand respect as a cherished piece of gear.
The ‘easy’ part of this only comes if you have access to a machine shop like [John] at NYC CNC does. To be fair, the only key machine for making these plates is a laser cutter, and even a guy like [John] needed to farm that out. The process is very straightforward — a brass plate is cleaned and coated with lacquer, which is then removed by the laser in the areas that are to be etched. The plate is dipped in an electrolyte solution for etching, cleaned, and powder coated. After curing the powder coat with a heat gun rather than an oven — a tip worth the price of admission by itself — the paint is sanded off the raised areas, the metal is polished, and a clear coat applied to protect the badge.
He stuck a 100W positive temperature coefficient heater into the bottom of the block using silicone glue, and the heater heated the block up in around half an hour. He connected a temperature controller to maintain the temperature at an ambient 95C, with a controller monitoring a thermistor to keep the block within the pre-determined range. The heater has an auto shutoff if it got too hot, so [abizar] felt safe keeping the dry bath on, unmonitored.
The aluminum block sits in a plywood box lined with rubber from an inner tube, with the heater underneath the block and the temperature controller underneath that, separated by more plywood from the heat. The result? A dry, temperature regulated bath for 20 1.5ml test tubes.
Anyone who regularly presents to an audience these days has known the pain of getting one’s laptop to work reliably with projection hardware. It’s all the more fraught with pain when you’re hopping around from venue to venue, trying desperately to get everything functioning on a tight schedule. [Seb] found that the magic keystrokes they used to deal with these issues no longer worked on the Macbook Pro Touchbar, and so a workaround was constructed in hardware.
The build itself is simple – an Adafruit Trinket serves as the brains, with a meaty 12mm tactile button used for input. The Trinket emulates a USB keyboard and sends the Cmd-F1 keypress to the computer when the button is pressed. The button’s even mounted in a tidy deadbugged fashion.
While it’s not at all complicated from a build standpoint, the key to this project is that it’s a great example of using the tools available to solve real-life problems. When you’re in a rush with 300 people waiting for your talk to start, the last thing you need to be worrying about is a configuration issue. [Seb] now has a big red button to mash to get out of trouble and get on with the job at hand. It does recall this much earlier hack for emulating a USB keyboard with an Arduino Uno or Mega. It’s a useful skill to have!
Back in the old days, when handing someone a DB serial cable when they asked for a DE serial cable would get you killed, KVM switchers were a thing. These devices were simple boxes with a few VGA ports, a few PS/2 ports, and a button or dial that allowed your input (keyboard and mouse) and output (video) to be used with multiple computers. Early KVMs were really just a big ‘ol rotary switch with far, far too many poles. Do you remember that PS/2 wasn’t able to be hot plugged? The designers of these KVMs never knew that.
Today, KVM switchers are a bit more complicated than a simple rotary switch. We’re not dealing with VGA anymore — we have HDMI muxes. We’re also not dealing with PS/2 anymore, and USB requires a bit of microelectronics to switch from one computer to another. For one of his many Hackaday Prize entries, [KC Lee] is designing a low-cost HDMI switch and USB mux. It works, it’s cheap, and if you need to switch a keyboard, mouse, and monitor between boxes, it’s exactly what you need.
First off, the HDMI switching. Designing a switch for HDMI would usually take some obscure parts, intricate routing, and a lot of prototyping time. [KC] found a way around this: just hack up a $5 HDMI switch. This cheap HDMI switch is as simple as it gets, with an HDMI mux doing the heavy lifting and an 8-pin microcontroller to handle the buttons and a selector LED.
For the USB, there are a few more design choices. For USB 1.x switching, [KC] figures he can get away with a 74HC4052 dual 4:1 analog mux. Yes, he’s doing digital with analog chips, the heathen. There are drawbacks to this: everything could break, and it’s only USB 1.x, anyway. For a USB 2.0 KVM, there are a few more professional options. The OnSemi NCN9252 is a proper USB 2.0 mux, and in the current design.
How do you tell how much load is on a CPU? On a desktop or laptop, the OS usually has some kind of gadget to display the basics. On a microcontroller, though, you’ll have to roll your own CPU load meter with a few parts, some code, and a voltmeter.
We like [Dave Marples]’s simple approach to quantifying something as complex as CPU load. His technique relies on the fact that most embedded controllers are just looping endlessly waiting for something to do. By strategically placing commands that latch an output on while the CPU is busy and then turn it off again when idle, a PWM signal with a duty cycle proportional to the CPU load is created. A voltage divider then scales the maximum output to 1.0 volt, and a capacitor smooths out the signal so the load is represented by a value between 0 and 1 volt. How you display the load is your own choice; [Dave] just used a voltmeter, but anything from an LED strip to some kind of audio feedback would work too.
Here’s some interesting work shared by [Ben Kromhout] and [Lukas Lambrichts] on making flexible 3D prints, but not by using flexible filament. After seeing a project where a sheet of plywood was rendered pliable by cutting a pattern out of it – essentially turning the material into a giant kerf bend – they got interested in whether one could 3D print such a thing directly.
The original project used plywood and a laser cutter and went through many iterations before settling on a rectangular spiral pattern. The results were striking, but the details regarding why the chosen pattern was best were unclear. [Ben] and [Lukas] were interested not just in whether a 3D printer could be used to get a similar result, but also wanted to find out what factors separated success from failure when doing so.
After converting the original project’s rectangular spiral pattern into a 3D model, a quick proof-of-concept showed that three things influenced the flexibility of the end result: the scale of the pattern, the size of the open spaces, and the thickness of the print itself. Early results indicated that the size of the open spaces between the solid elements of the pattern was one of the most important factors; the larger the spacing the better the flexibility. A smaller and denser pattern also helps flexibility, but when 3D printing there is a limit to how small features can be made. If the scale of the pattern is reduced too much, open spaces tend to bridge which is counter-productive.
Kerf bending with laser-cut materials gets some clever results, and it’s interesting to see evidence that the method could cross over to 3D printing, at least in concept.
He built a LEGO-looking enclosure for the battery as well, based on a 2×6 brick. The battery pack sits behind the motor with the tail light on top and holds the radio control receiver as well the twin LiPos. The head and tail lights pack 24-LED discs and are controlled by [James]’ FS-GT2B 3-channel RC transmitter. Its third channel is just a button, and he can trip that button to activate the lights with the help of a Turnigy receiver-controlled switch.
For an added touch he printed some LEGO flowers and a minifig, suitably oversized, and took the skateboard on the road. The thing has some zip! [James] kept his balance while holding the controller in one hand and a selfie stick with the other. The headlamp housings fell off, and a while later the minifig fell off. Fortunately [James] was able to snap them back into place, in proper LEGO fashion.