Keyswitch connector 3d-print madness!

After I started to design a keyboard of considerable awesomeness, I've had trouble finding way to temporarily connect keyboard matrix into keyswitches.

Soldering creates way too permanent construct for a keyboard layout that may change a day after I test it. The geekhack "enabler" would work if you supply it with machine pin headers. But I'd have to wait for weeks to get all the supplies.

All I got are the cherry mx switches, arduino, 1N4148 diodes, some copper sheet and a 3D printer. And like a big manchild, I can't wait. I attempted to make a keyswitch connector with integrated diode that I could daisy chain. Anyone interested about creating connectors by 3D printing read ahead.

It's fucking hard to create a functioning connector with 0.1mm FDM

Fused deposition modeling has the problem it's not precise enough to print very complex connector design. The design must be relatively simple to print well. I learned the channels, holes, and stress reliefs are all shapes that print out in frigging intolerable tolerances and have to be precisely dimensioned for connectors to print.

Spring forces required by connector are hard to achieve with household items

We tried to create a connector that would keep wire connected with small plastic spring. But a spring made from PLA easily budges. There's even worse effect you should know about though: A standard copper wire is perfectly capable to chisel plastic dust out of the connector, wearing out the connector even after just two connects.

If you test such a connector, the testing wears it out.

You need sheets of metal, copper wire won't connect in a connector

You can't just put the plastic part to mechanically press on every part you have. We tried that. It became a trouble because it was unreliable way to connect and you had to connect everything at once for it to work. So you need a conductive element that connects everything you plug into the connector.

We first tried to do this with bare copper wire. Two of 10 connectors did well. The relatively large wire also formed an easy failure point for connecting the diode and another keyswitch leg. Wire would sometimes stuck and assembling the connector would require so much force that you break the whole brittle connector.

Aluminium foil is too thin

Once I were aware that metal sheet was required, I first considered aluminium foil, but my plans were foiled when I realized how easily the wire punctures a foil. You need a sheet with thickness. But I'd consider 0.5mm to be already too thick. Less than 0.2mm and it's too thin though.

I didn't get to try solder wick made of copper. But it may provide challenge in providing the needed spring force to connect.

It's fucking hard to assemble a 13x13mm connector by common household items

The thing you operate on is about the size of your fingernail. You would have to cut and fit a metal sheet size of a ribbon into crevice that fits it. These are the kind of products that are completely ineconomical to do by hand. I was only going to do a small batch of them anyway though.

One of our designs was so hard to assemble that we discarded it just because of that.

Only thing to make it work is to squeeze the wire between sheets

I haven't yet constructed a working connector. But any method that relies on metal-metal-plastic connection suffers from the problem that the plastic gives up. Therefore only thing to make this work is to squeeze the wire between sheets rather than plastic.

I'm not sure even if that works. But then real connectors are just plastic and metal too anyway! Except that they come out from a fancy industrial factory line that makes millions of them in a hour.

After all the attempts that failed, I'm pretty much exhausted here. But I still got two more to go! I'll see if either one does. You will read about this from my next keyboard blog post.

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