Switch Tester Servo-Slaps Them ’til They Fail

[James] is designing an open-source 3D printed keyboard switch, with the end goal of building a keyboard with as many printed parts as possible. Since keyswitches are meant to be pressed quite often, the DIY switches ought to be tested just as rigorously as their commercial counterparts are at the factory. Maybe even more so.

The broken spring after 13,000+ automated boings.

Rather than wear out his fingers with millions of actuations, [James] built a robot to test switches until they fail. All he has to do is plug a switch in, and the servo-driven finger slowly presses the slider down until the contacts close, which lights the LED.

The system waits 100ms for the contacts to stop any tiny vibrations before releasing the slider. That Arduino on the side tracks the contact and release points and sends them to the PC to be graphed. If the switch fails to actuate or release, the tester stops altogether.

We love that this auto-tester works just fine for commercial switches, too — the bit that holds the switch is separate and attaches with screws, so you could have one for every footprint variant. [James] recently did his first test of a printed switch and it survived an astonishing 13,907 presses before the printed coil spring snapped.

One could argue that this doubles as a servo tester. If you want a dedicated device for that, this one can test up to sixteen at a time.

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A Custom Keyboard At Maximum Effort

No one loves hacked keyboards more than Hackaday. We spend most of our workday pressing different combinations of the same 104 buttons. Investing time in that tool is time well spent. [Max] feels the same and wants some personality in his input device.

In the first of three videos, he steps us through the design and materials, starting with a layer to hold the keys. FR4 is the layer of fiberglass substrate used for most circuit boards. Protoboards with no copper are just bare FR4 with holes. Homemade CNC machines can glide through FR4, achieving clean lines, and the material comes in different mask colors so customizing an already custom piece is simple. We see a couple of useful online tools for making a homemade keyboard throughout the videos. The first is a keypad layout tool which allows you to start with popular configurations and tweak them to suit your weirdest desires. Missing finger? Forget one key column. Extra digit? Add a new key column. Huge hands? More spaces between the keys. [Max] copied the Iris keyboard design but named his Arke, after the fraternal sister to Iris which is fitting since his wrist rests are removable. Continue reading “A Custom Keyboard At Maximum Effort”

Nixies And Raspis For A Modern Vintage Calculator

There are a few very rare and very expensive calculators with Nixie tube displays scattered about calculator history, but so far we haven’t seen someone build a truly useful Nixie calculator from scratch. [Scott] did just that. It’s a complete, fully-functional electronic calculator with all the functions you would expect from a standard scientific calculator.

The calculator uses IN-12 Nixies, the standard for anyone wanting to build a clock or other numerical neon discharge display. Each Nixie is controlled by a K155D driver chip, with the driver chip controlled by an I2C IO expander.

The keypad is where this gets interesting; electronics are one thing, but electromechanicals and buttons are a completely new source of headaches. [Scott] ended up using Cherry MX Blue switches, one of the more common switches for mechanical keyboards. By using a standard keyboard switch [Scott] was able to get custom keycaps made for each of the buttons on his calculator.

The brains of the calculator is a Raspberry Pi, with the I2C pins going off to listen in on the several IO expanders on the device. A Raspi might be a little overkill, but an Internet-connected calculator does allow [Scott] to send calculations off to WolframAlpha, or even the copy of Mathematica included in every Pi.

[Scott] has put his project up on Kickstarter. Videos below.

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