About that DIY keypad

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This panel is part of a long-running project to build a simpit for Elite Dangerous. It is the keypad for the navigation computer that will replace the standard QWERTY keyboard, adding some nice features and a immersive design.

I made the panels and switches by painting transparant acrylic sheets with Humbrol modelling paint (comes in a small spray can). This paint is specially made for plastics, has very good adhesion and doesn’t melt when lasercutting. I have to paint several layers for it to become opaque (hold it against the light and check that no light bleeds through).

After the paint is done I can engrave the panels so that the white below the paint comes through.

The comes the engraving/cutting. All the panels we lasercut with the 40W lasercutter we have at my local hackerspace; i must have spent several hours sitting next to it by now! At first I wanted to make a proper PCB for the switches. But as this is a one-off prototype and PCB’s for this size are pretty expensive i tried to do it by hand. After designing the layout in AutoCAD 2016 I added several layers in my diagram:
1) switch solder panel (2mm,my alternative for the PCB)
2) support panel (actually wasn’t needed but it serves as a good standoff panel right now).
3) button panel (5mm thick creme transparent white with black paint)
4) button retaining panel (2mm white)
5) front panel (3mm thick creme transparent white with dark grey paint)

Because the buttons are 5mm and the front panel is only 3mm, the buttons stick out by 2mm which gives are nice glowing effect when they are lit.

Layer #4 is something that came up last-minute since my previous solution didn’t work. These are little plates that are glued to the backside of the buttons so they do not fall out. The buttons themselves are 13×13 (wider ones are 21×13) and the backplate is 15×15 to give them a 1mm border.

This all comes together in a stack. The distance from the pseudopcb to the buttons is fixed with a few stand-offs, but exactly high enough so that the spring tension of the switches pushes the buttons against the front plate without actually making contact. These tact switches have only 0.5mm travel.

Pictures!

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Load of wiring because of the LEDS and the Switches

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Prototype

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Closeup

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Sorting the buttons

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Button back side

 

 

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