Markus’ Blog

Bypassing a deficient button with a high quality Cherry MX keyboard switch

by on Jan.13, 2013, under Electronics

geeky designA few years ago we bought a Soehnle digital kitchen scale. We were still happy with it if it was not for the crappy “on-tara-off” button: Within two or three months of daily use, being exposed to small amounts of flour, water, sugar powder etc., the button becomes more and more sticky. In the end, the scale doesn’t turn on or off or reset to zero when pressing the button with the usual pressure. This is an enormous drawback for usability and satisfaction.

Of course this can easily be fixed by opening the scale and cleaning the button and surrounding parts. Unfortunately the fix will only last for two to three months…

So I decided to no longer settle for temporary fixes. It is very easy to connect a different switch parallel to the original one. Being a great fan of Cherry MX keyboard switches, I went for a Cherry MX switch resurrected form an old keyboard.

hole for switch

There are various types of Cherry MX switches available: The one I have installed is a tactile, non-clicky one (these are often referred to as “Cherry MX Clear”). Other then the original button the new one now has a good pressure point. This results in enormously improved feedback.

It took me just a few minutes to cut a perfectly fitting hole into the scale cover.hole from outside

hot glue insideWith superglue holding the switch in position, I applied lots of hot glue to permanently attach the new switch.
Then I clogged up the gaps on the outside with epoxy.key and epoxy

 

Finally I had to decide which key cap to go for: Having all the parts from the old keyboard at hand I had more than 100 designs to choose from :-)
Mscale with cherry mxy whole family likes the result of this very simple hack. It did not cost me anything, was completed in less than an hour and the MX’s lifespan of up to 50 million actuations should save me from having to do something about sticky buttons for the next couple of years.

 

 

 

PS: Being so happy with the button bypass, I am now thinking about also bypassing the original digital controller: So I could get rid of the annoying “auto power off” feature. And a new controller would also open the option for replacing the original display with a nixie tube one…


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