The Buckling Spring

Bigfoot & Other Updates

During the last several weeks, I have not been able to work on my “Technical Manual” project. I was incredibly busy at work and couldn’t find the muse whenever I had a few spare moments. I needed manual work to relax, and what better can be done than restoring a wonderful old keyboard?

When I received my IBM 5291 keyboard – also known as Bigfoot, it was in technical good condition. All keys were buckling and there was no major rust to be seen. Surely, a lot of debris has been accumulated for the decades and there was dirt to be seen on the surface (keys and case) but as well inside. The foam was bad and very much what you get with an old Beamspring keyboard. A gooey substance sticking on the barrels and barrel plate.

After some cleaning of the usual kind (Ultrasonic cleaner for the smaller parts like keycaps and barrels / Cleaning the rest with soap, warm water, magic eraser) I had a nice set of parts in front of me that needed some further love.

I order two parts for the project. First, I built a template for the laser-cutting company of my choice and ordered a bunch of foams made out of 2mm thick neoprene. The result was spot on as you can see in the picture below:

Next, I needed the right controller. It had to be a beamspring controller of the universal type (rev 1.3). As the bigfoot is based on a Sensing PCB with a 23 x 4 matrix, the Model F controller won’t work.

Meanwhile, I was starting to remove all active and passive components from the Sensing PCB and solder on single wires to each column, row and ground directly to the PCB. Being paranoid, I also cut all traces leading to the controller part of the pcb:

Once the controller did arrive, I soldered it on and programmed QMK to work with it. With the support from Andrei Purdea I could get it properly working within a hour.

A beautiful keyboard that is better than the original IBM PC / XT keyboard in my opinion.

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