Replaced spring keys with microswitches.

[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.
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 (8.73 KiB) Viewed 1391 times

Repetier output.

Repetier.JPG (11.4 KiB) Viewed 1391 times

Start 3d printing.

Parts ready.

With those parts mounted i can safely turn the atom around.

Jan

[Multiwizard]

Nice (mooi werk)...


Greetings, Wim...

[1024MAK]

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

Mark

[IanS]

Have you seen this thread - viewtopic.php?p=249145#p249145

[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.

[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.

See dots in red on opposite side PCB.

In the pic below you can see the microswitch.

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.

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 ….. ).

Kind regards,

Jan

[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.

[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???

[janvb]

Hi Ken,

I used these switches. (4pins)

used switch.JPG (10.45 KiB) Viewed 1210 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

[janvb]

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 (10.45 KiB) Viewed 1208 times

They have indeed a short travel.
You cant compare these with a mechanical keyboard. But it works fine for me

Jan

[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.

[KenLowe]

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...

[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

[Trevor_B]

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.
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