Flakey keyboard presses?

i’ve gotten my picocalc just a couple of days ago, i’ve since uploaded the Custom PicoCalc BIOS/keyboard firmware to it for reference

has anyone else noticed keypresses not being too consistent? i don’t think this is any fault with either the stock or custom keyboard firmware, but rather the switches. if i type too fast i press the keys a bit soft and i need to go back and press them harder for it to register - what i mean is that the click of the switches on the board don’t always translate to a key input. i think the problem is more likely mechanical than not (i can 100% consistently press the D and U keys soft enough to click but not register for example, those in particular need to be pushed slightly harder past the click to register as keypresses)

i’m not above replacing all the smd buttons on the board for higher quality ones, but first i wanted to hear out if anyone else has been noticing a similar issue!

Some of my keys (‘9’,’0’,’U’ and ’;’) have the same issue you describe.

But, I really need to force myself to press it “lightly” to miss a key press. In a normal usage, I didn’t have to press a key again so often (or so rare that I didn’t even notice it).

The “caps” buttons used aren’t efficient/have a short lifespan compared to a “real” mechanical key. I suppose we’ll need to replace them sooner or later…

it’s not all of the keys but enough of mine are definitely flaky enough that it’s not difficult at all to click them and not make a keypress

next time i can bother to open the picocalc i’ll measure the switches and figure out replacements for them and report back with my results :slight_smile:

Yes noticed this since April, not bad enough to annoy but sometimes slows me down for sure. I get a click, but nothing produced till I click again… STM32 bios v1.2 (same with first version).

What I have noticed is that what matters is not how hard I press the keys but rather that I press the keys square in the center and not at an angle. Now that I have trained myself to do so I rarely miss keypresses except when I am trying to do some control-key combos due to my tendency to press the control key off-centers when doing so, where as a result often the control key does not register.

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The root cause is that the posts in the rubber keymat are too flexible. The tactile domes themselves are super robust and super reliable, but you have to press them hard enough. The rubber absorbs some of the pressure so you have to press them harder than you would a rigid plastic key to provide the same amount of force to the dome. And when the dome “pops” it flattens slightly, which reduces the pressure on the dome even further. So pushing just hard enough to feel the dome pop lands you right in the problem zone.

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here’s a closer look at the switches for further reference, i measured roughly 4.7-5mm to a side, 0.5mm depth

i couldn’t find ones that look exactly the same on aliexpress, these are the closest ones (the 4*4*0.8 option) https://www.aliexpress.com/item/1005006486926948.html

not yet sure if i’ll go through with an attempt to replace the switches (simply due to effort, i’ve done this kind of SMD before) but figured i’d at least document this far :slight_smile:

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I’ve looked a week or so ago, and found one that looks like a match, but the seller had the nerve to ask $15 for just one.

Just didn’t an image search and found something really close on AliExpress, and with the dimensions I was expecting, 4.8mm × 4.8mm × .55mm, and cheap.

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I recieved they switches, and the do appear to be an exact match!


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I put a tiny dot of super glue on each dome, raising it by a couple mm. Now the keys don’t have to be pressed quite so far to register.

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