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Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 12 Oct 2020, 05:40
by TrichotomySigil
TLDR = Plugging (Kailh's) hot-swappable switch sockets into a 3D-printed "PCB" (or laser-cut), hot-gluing them in place for support, and handwiring them like any other handwiredbuild, but allows you to change switches at any point thereafter instead of having to desolder the board.

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Hey guys,

First time building a custom board myself, starting from scratch though; and I'll be building three keyboards with custom layouts, and will be handwiring them since the layouts are completely custom (including multiple rotary encoders) and PCBs, afaik, are hard to design and expensive to make.

Not wanting to think about desoldering a handwired keyboard anytime I want to change switches in the future after the build (especially since one of them is a gift I'm making for someone), I started looking at hotswappable switch sockets, and mostly realized that it wasn't going to work since there's no PCB to hold the sockets in place every time you removed and installed a switch into the plate.

But then I had an idea: What if I 3D-printed a "dummy PCB" and plugged hot-swap sockets into them (from below or above, though below makes more sense, especially if the holes are snug around the connectors and then hot-glued in place), then handwired them to a diode like you would with any other switch pins?

This would effectively allow you to create a PCB by using a faux-plate/PCB to hold the sockets in place, while using the typical handwired techniques in order to create the same connection that PCB traces are made to do. Then, obviously, just wire all the rest to a controller, etc.

You could, theoretically, use Kailh's hot-swap sockets and plug them into holes made in the "PCB" which can be OR push some TE Holtite 8134-HC-8P3 into the PCB, like the man in this video has done with a proper PCB.

Haven't seen someone post this idea yet, so it might be something interesting for other builders if it works. Would make the pain of building a handwired board more tolerable.

Is this possible, or have I missed something? Let me know.

I'd encourage anyone to test this themselves, if they'd like. I haven't bought my parts just yet (not even a 3D-printer), so I can't test it yet, nor would I know how to do so without completing the build.

Any ideas are welcome, and any help for 3D-printing/modelling is welcome as well, as I'm learning that stuff for the first time as well :) Haven't even thought about how I'm going to QMK my rotary encoders yet...

****Post may be mirrored on r/MK and Geekhack****

P.S.: Two of the boards I'm building are BIG (7 rows, 26 columns), so, I think, I can only get a small controller for one of the boards and would need a bigger one for all the points on the bigger boards. Any suggestions? Would THIS be enough?

Re: Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 12 Oct 2020, 11:49
by kmnov2017
TrichotomySigil wrote:
12 Oct 2020, 05:40
...ad PCBs, afaik, are hard to design and expensive to make....
PCBs are actually quite cheap, JLCPCB can make them for less than 5 bucks a piece. MOQ is 5 though.
Github has several 100 open source PCBs for anyone to make...

Re: Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 12 Oct 2020, 13:33
by vvp
You can do it easily. If I would use Kaih hot-swap sockets then I would glue them to the 3d-printed plate with something more serious (e.g. abs-glue for abs plate or locktite for PLA plate, or some epoxy). Hot glue will not be strong enough ... probably.

The only thing I would be afraid about is how soon the sockets start to fail. Connectors like to fail when in vibration environment. Maybe a keyboard will not vibrate enough for this to be a problem. You will see after a few years of use.

Re: Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 12 Oct 2020, 20:35
by zzxx53
Agree with kmnov. Designing a PCB and then solder on the hot-swap sockets will be the cleaner and more precise solution in the long run, and you won't have to hand wire anything, so less chance of the soldering joints coming loose over time.

Re: Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 13 Oct 2020, 10:30
by vvp
Hand wiring a keyboard takes about 3.45 hours based on my measurements on K84CS.
You possibly can design PCB in about 2.5 hours, maybe sooner if automatic routing does a very good job for you. Add about half an hour sending an order a retrieving the package. And it is almost the same time overall. The great thing about PCB way is that you can get easily many PCBs of the same design and it is overall more solid (one can go without the plate if switches are soldered directly to the PCB).

The way to quickly hand wire keyboard is using bare wires in one direction and enamelled wires in the other direction (and burning through the enamel at the places where it needs to be soldered to a switch). E.g. viewtopic.php?p=346079#p346079

Re: Idea = "3D-Printed PCB" For Hotswappable Handwired Keyboard (Could Use Help, Too)

Posted: 13 Oct 2020, 23:01
by gipetto
this fellow used handwired holtites in acrylic like you were wondering about.

https://www.reddit.com/r/MechanicalKeyb ... _40_ortho/