wcass' Compact SSK: a review, reverse engineer, teardown, geek-out.

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Techno Trousers
100,000,000 actuations

04 Jan 2019, 23:33

I'd be fine with clamping a flat PCB between F-122 plates and heating it with a hot air gun or hair dryer until it takes on the curve. IIRC, that's what I$ did for the original FSSK.

The problem with strips are the interconnects between them. Lots of potential points of failure there.

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Muirium
µ

05 Jan 2019, 00:24

True. But from what I gather the FSSK had its own problems, quite plausibly from that hand bent PCB. I’d much rather have a kit of single row PCBs, even if I had to solder connections myself, than a single costly board I had just one shot to bend. The thought of waving around a heat gun to coerce the very heart of the thing gives me shivers!

__red__

05 Jan 2019, 04:02

Hypersphere wrote: The technology has existed for some time to make roll-up musical keyboards, and now foldable phones and displays are making debuts. Should it not be possible to use the same technologies to make flexible keyboard PCBs?
I just haven't found the lack of curve to be any issue. Try it before you overcomplicate it.

But, since we're talking about overcomplication:

You can do 0.4mm PCBs which may be flexible enough without needing to be abused - it's expensive.

You can do a real, genuine flexpcb, but now you're talking real money - especially if you go to 4 layers.


Lastly - given that capacitance varies based on the distance between the plates, the dielectric, and the thickness of the copper you're going to end up with significantly different analog values at the controller. You may want to poll DMA to check with him about potential firmware changes needed to adjust the range.

It's certainly not impossible, but it'll be spendy.

__red__

05 Jan 2019, 04:11

For 300x200mm (4 layer):
1 -> $300
10 -> $78
100 -> $25

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Muirium
µ

05 Jan 2019, 04:20

Easy: one CommonSense controller per row! And I name this sweet idea NonSense…

Anyway, I, for one, find spaced out caps (which were designed for a curved backplate, not a plane) to be an aesthetic and likely functional showstopper. The curve is there for a reason. Going flat transforms the character of the keyboard.

Depends how much you can stand flatness, I suppose. I like my caps cylindrical and row contoured, so, for me, IBM caps on flatness is striking to the point of a straight up no-go.

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Darkshado

05 Jan 2019, 04:59

Speaking of flexible PCBs, this popped up on my FB feed earlier today: https://blog.hackster.io/new-from-osh-p ... f343d6ebd3 I did not run the numbers for a typical keyboard though

__red__

05 Jan 2019, 05:38

Muirium wrote: Depends how much you can stand flatness, I suppose. I like my caps cylindrical and row contoured, so, for me, IBM caps on flatness is striking to the point of a straight up no-go.
To be clear, my daily driver is an F-122 at full incline so I'm pretty much typing at a 45 degree angle ;-)

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Sangdrax

05 Jan 2019, 11:35

depletedvespene wrote:
Sangdrax wrote: The only material upgrade I could imagine would be using a 4 axis mill to tool everything the same way but with the classic profile curve.
Would it be at all possible to make, for a lack of a better term, a set of PCB strips, all to be connected to the "main"
Yes. The only thing that matters is the pads themselves be aligned under the switches. You could even connect the strips via ribbon cables and then have the last strip connect to the controller. I've seen it done that way on Magnetic valve battleship boards which are just as finicky in sensing.

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Muirium
µ

05 Jan 2019, 18:29

__red__ wrote: To be clear, my daily driver is an F-122 at full incline so I'm pretty much typing at a 45 degree angle ;-)
When you're all hoist up like that, things are different, I'm sure. I use my boards flat on the desk (or my lap) so I'm very aware indeed of the flat ones vs. row profiles. As pretty as DSA can be, I always prefer sculpted caps on flat boards, and my IBMs as they were designed! Curve matters.

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Hypersphere

05 Jan 2019, 20:47

I'm in full agreement with Murium -- curve matters!

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