The first prototype: part 1

Materialen PrototypeThe supplies for the first prototype are in. In the picture you see 30 microswitches, keycaps, wire, a crimptool, crimp terminals, the teensy microcontroller and a few 3-colored LEDs.

Unfortunately the keycaps did not fit on the microswitches. The red pin is very short and relatively wide while the keycaps need a virtually square, slightly longer pin. Time to take a closer look at the switches.

omron vx5-1a2 micro schakelaarAs it turns out it’s relatively easy to open the switch without damaging it with a bit of careful prying with a screwdriver. It is held together with a pin, no sealing or screwing involved. The upper metal leaf takes care of the tactile and audio feedback. By simply looking at this it appears the feedback is pretty much spot on with the activation point. The downside is that there is no increased resistance after activation, and thus it’s easy to damage the switch by applying too much force.

The pin can easily be taken out and adapted. We could install a longer and slimmer pin, but this would probably shorten the lifespan considerably as it would be easier to overextend the leafs. Another possibility is to file off part of the case, but that would pose the same problem, even worse, debris could easily get into the switch and we’d probably break a lot of switches in the adaption process.

It’s unlikely that there are fitting keycaps on the market. These switches are exclusively used industrially so keycaps are usually designed and produced by the buyer. We’ll have to come up with something ourselves.

omron vx5-1A2 keyThe switches will be installed vertically, so the weight of the key is not an issue (horizontally the weight of the key might activate the switch). Optimally the keys would be narrow and long, so you don’t accidentally press the wrong key but vertical finger placement isn’t very important. It’d also be good for the keys to have an early ‘stop’ to increase the lifespan of the switches.

This can all be realized easily. An oblong piece of thin material with a small bump (a drop of glue?) would suffice. Attaching it will be harder. We could use the holes in the switches but that would pose problems for the switch installation. Separate fastening of the key with a small hinge will probably be easiest. We’ll have to do some testing to see if the hinge has a considerable effect on the tactile feedback and force profile.

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