Replaced spring keys with microswitches.

emulators, hardware and classic software for atom + system machines
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janvb
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Replaced spring keys with microswitches.

Post by janvb »

Hi all,

As mentioned before, the keyboard of my atom had several broken keys witch I couldn’t fix. The disassembly of the keyboard was a pain in the ass. I broke several more keys with that operation. In the end decided to replace the spring-contacts with micro switches. Since most of the springs where broken, I removed them all.
Micro switches don’t need return springs. Most of the plastic parts didn’t survive the nasty job either.
Now if I have to turn the acorn on his back, halve of the keys fall out. :lol: :roll:
What a disaster. But the acorn works. :)
Decided to make some new parts for the keyboard.

3D model of the part made in solid edge.
Model.JPG
Model.JPG (8.73 KiB) Viewed 1378 times
Repetier output.
Repetier.JPG
Repetier.JPG (11.4 KiB) Viewed 1378 times
Start 3d printing.
3d-print start.jpg
Parts ready.
3d-print finish.jpg
With those parts mounted i can safely turn the atom around.

Jan
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1024MAK
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Re: Replaced spring keys with microswitches.

Post by 1024MAK »

The wonders of of 3D printers and what their owners create with them is always amazing =D>

Mark
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IanS
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Re: Replaced spring keys with microswitches.

Post by IanS »

Have you seen this thread - viewtopic.php?p=249145#p249145
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KenLowe
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Re: Replaced spring keys with microswitches.

Post by KenLowe »

The printed keyposts look really good. I bought some 3D printed ones online. They cost me a fortune, but are marginally too fat so don't move freely in the plastic frame. I was going to try and sand them down a bit, but that's on hold for now. I'm also having similar issues with the spring/contacts, so I'd be interested to know exactly what you've done with the micro switches, and how you're using the keyposts to interface with the micro switches. Do you have any photos of the atom board you could share?

Thanks
Ken.
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janvb
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Re: Replaced spring keys with microswitches.

Post by janvb »

Hi Ken,

The fix i made, maybe not the best, but it worked fine for me.
At first i was very anxious to disassemble the keyboard, cause its very fragile. It was also the only preassembled part in the kit I bought way back in the early eighties.
I tried to remove the keyposts from the broken switches. But as mentioned before, I didn’t succeed in that.
Long story short. De-soldered all the springs so I could remove the keyboard frame from the PCB. Then between the 2 holes of each key connection (in the center) I soldered a microswitch.
back keyboard.jpg
See dots in red on opposite side PCB.

In the pic below you can see the microswitch.
microswitch.png
As you can see I don't use the springs anymore, most of them were broken and the micro switches don’t need them. For the switches to fit beneath the keyboard frame, I had to remove a square area of the frame for each switch. I did this with a dremel tool.

As you can see on the 3d printed keyholders, the spring guiding thingies I have omitted.
3d printed parts.png
The middle pin, wich activates the microswitch, has a tiny upstanding edge so the post want fall out.
If you need more information, let me know. ( I wrote this quick and ….. :D ).

Kind regards,

Jan
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BigEd
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Re: Replaced spring keys with microswitches.

Post by BigEd »

What kind of switches are these? It looks a little like the 'tactile' switches I've seen used in calculator rebuilds - they have rather short travel.
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KenLowe
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Re: Replaced spring keys with microswitches.

Post by KenLowe »

Thanks Jan. That's useful information. Do you have details of the micro switch that you've used?

I've been having a look on ebay for some suitable micro switches, and I'm pondering something like this:

https://www.ebay.co.uk/itm/50pcs-3-4-2- ... SwDmRZ4cFf

It looks like these micro switches might just about fit inside the keyboard frame. In this case I would probably still look to retain the two spring / contacts for each switch post, but do away with the contact part of the spring. This would allow the switch post / keycap to fully return to the normal unpressed position. The other thing I'm not sure about is if the middle pin of the switch post would be long enough to hit the microswitch. If not, then I guess it would be necessary to 3D print new switch posts with slightly longer middle pins? Probably time for me to invest in a 3D printer...

Thoughts???
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janvb
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Re: Replaced spring keys with microswitches.

Post by janvb »

Hi Ken,

I used these switches. (4pins)
used switch.JPG
used switch.JPG (10.45 KiB) Viewed 1197 times
I guess the ones on eBay are the same.
You can buy these with different button heights, from as small as 3,1mm to as high as 15mm total length.
So you don't have to buy new key or switch posts by choosing the right height for the micro switches.
For the keyboard frame you have 2 options:

1 - You lift the frame above the microswitches, approximal 3mm I thought with distance holders.
Then you don't have to mod the frame.
2 - Make openings in the frame, so it fits over the switches.

Jan
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janvb
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Re: Replaced spring keys with microswitches.

Post by janvb »

BigEd wrote:
Thu Apr 02, 2020 9:01 pm
What kind of switches are these? It looks a little like the 'tactile' switches I've seen used in calculator rebuilds - they have rather short travel.
I used these
used switch.JPG
used switch.JPG (10.45 KiB) Viewed 1195 times
They have indeed a short travel.
You cant compare these with a mechanical keyboard. But it works fine for me :D

Jan
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BigEd
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Re: Replaced spring keys with microswitches.

Post by BigEd »

Looks like a good solution!

Just a thought, if you cut short the central pin which pushes the switch, and put some foam in (maybe expanded polystyrene, maybe that black anti static foam), would you get more of a longer travel and more progressive force until the switch trips? You could tune it according to the thickness of the foam.
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KenLowe
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Re: Replaced spring keys with microswitches.

Post by KenLowe »

janvb wrote:
Fri Apr 03, 2020 3:16 pm
Hi Ken,

I used these switches. (4pins)
used switch.JPG
I guess the ones on eBay are the same.
You can buy these with different button heights, from as small as 3,1mm to as high as 15mm total length.
So you don't have to buy new key or switch posts by choosing the right height for the micro switches.
For the keyboard frame you have 2 options:

1 - You lift the frame above the microswitches, approximal 3mm I thought with distance holders.
Then you don't have to mod the frame.
2 - Make openings in the frame, so it fits over the switches.

Jan
That's for that additional information. I'm going to order up some micro switches, and see how I get on. I suspect I may still need to get modified posts, but let's wait and see...
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janvb
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Re: Replaced spring keys with microswitches.

Post by janvb »

[/quote]That's for that additional information. I'm going to order up some micro switches, and see how I get on. I suspect I may still need to get modified posts, but let's wait and see...
[/quote]

Succes Ken
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Re: Replaced spring keys with microswitches.

Post by Trevor_B »

janvb wrote:
Wed Apr 01, 2020 7:58 pm
Hi all,

As mentioned before, the keyboard of my atom had several broken keys witch I couldn’t fix. The disassembly of the keyboard was a pain in the ass. I broke several more keys with that operation. In the end decided to replace the spring-contacts with micro switches. Since most of the springs where broken, I removed them all.
Micro switches don’t need return springs. Most of the plastic parts didn’t survive the nasty job either.
Now if I have to turn the acorn on his back, halve of the keys fall out. :lol: :roll:
What a disaster. But the acorn works. :)
Decided to make some new parts for the keyboard.

3D model of the part made in solid edge.
Model.JPG
Repetier output.
Repetier.JPG
Start 3d printing.
3d-print start.jpg
Parts ready.
3d-print finish.jpg
With those parts mounted i can safely turn the atom around.

Jan
Hi Jan

I've been looking for the plastic inserts for a while - I've got an atom with 2 broken keyboard inserts but otherwise working fine. I've also got a 3d printer...

Would you be willing to share the STL file for the inserts, and I promise I'll print more than I need and make them available for others!

Trevor
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