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geekhack Projects => Making Stuff Together! => Topic started by: cool-RR on Mon, 28 October 2013, 07:00:15

Title: Clasp for Cherry Brown
Post by: cool-RR on Mon, 28 October 2013, 07:00:15
Hi guys,

I'm working on the design of my super-keyboard. Question: How is my construction supposed to hold the Cherry Brown keyswitch in place? I notice that there's a flexible part on the side of the keyswitch that looks like it's made to be clasped, but I don't know how.

Is there a 3d model of the kind of clasp needed for this?


Thanks,
Ram.
Title: Re: Clasp for Cherry Brown
Post by: infiniti on Mon, 28 October 2013, 09:33:23
Check out the GH CAD Resources Hub (http://geekhack.org/index.php?topic=47744).

What you're looking for are the dimensions for the switch mounting cutout.  You can check out the following in Reply #1 (http://geekhack.org/index.php?topic=47744.msg1019782#msg1019782):

You might find this thread helpful as well: Prototyping New Keyboard Designs (Using Plate Mounting and Direct Wiring) (http://geekhack.org/index.php?topic=40567.0)

Good luck with your project super keyboard project! ;D
Title: Re: Clasp for Cherry Brown
Post by: Findecanor on Mon, 28 October 2013, 10:14:09
PCB-mounting:
 - Switch pins soldered to PCB
 - Jumper, diodes or LED soldered to PCB
 - Plastic pins go through PCB.

The four soldered pins prevent pulling. The pins are distributed around the centre for better stability.
On some keyboards with PCB-mounting there can be switches with jumpers soldered to pads that are not connected to anything.
The plastic pins prevent twisting.

Plate-mounting:
 - Switch pins soldered to PCB
 - Plate edges surrounds the switch
 - Snaps in switch housing locks switch in plate.

Soldering prevents pulling.
Plate edges against switch housing prevent twisting. The switch has ledges resting on the plate for better stability.
Snaps in switch housing prevent pulling, but the plate must not be too thin or too thick or the snaps won't lock properly. Plates should be 1.5 mm thick.

Stabilisers are also mounted to either a plate or a PCB.
Title: Re: Clasp for Cherry Brown
Post by: cool-RR on Mon, 28 October 2013, 14:53:09
Thanks for this metric ****ton of info guys  :) :) :)
Title: Re: Clasp for Cherry Brown
Post by: cool-RR on Tue, 29 October 2013, 09:58:50
Here's something that confuses me. I saw CPTBadAss post this cutout for a Cherry switch:

(http://i.imgur.com/FeggbO6.png)

This looks great, but in a bunch of other places on Geekhack I saw Cherries mounted on a simple rectangular hole. Which one should be used, the complex cutout above or a rectangular hole?


Thanks,
Ram.
Title: Re: Clasp for Cherry Brown
Post by: SpAmRaY on Tue, 29 October 2013, 09:59:28
Quote from: cool-RR on Tue, 29 October 2013, 09:58:50
Here's something that confuses me. I saw CPTBadAss post this cutout for a Cherry switch:

Show Image
(http://i.imgur.com/FeggbO6.png)


This looks great, but in a bunch of other places on Geekhack I saw Cherries mounted on a simple rectangular hole. Which one should be used, the complex cutout above or a rectangular hole?


Thanks,
Ram.

This cutout allows for switch tops to be removed for modding purposes without desoldering.
Title: Re: Clasp for Cherry Brown
Post by: cool-RR on Tue, 29 October 2013, 10:06:00
Do you think I can use this cutout, but instead of having a metal plate, use a plate that's 3d-printed and made from whatever plasticy material the 3d printers use? The reason I want to 3d print is because my keyboard won't be a plate so I don't think I can cheaply manufacture a complex shape out of metal.
Title: Re: Clasp for Cherry Brown
Post by: SpAmRaY on Tue, 29 October 2013, 10:07:04
Quote from: cool-RR on Tue, 29 October 2013, 10:06:00
Do you think I can use this cutout, but instead of having a metal plate, use a plate that's 3d-printed and made from whatever plasticy material the 3d printers use? The reason I want to 3d print is because my keyboard won't be a plate so I don't think I can cheaply manufacture a complex shape out of metal.

I'm sure someone with 3d printer experience will chime in on that one, I have no idea if the tolerances would be tight enough or if the material would be strong enough.
Title: Re: Clasp for Cherry Brown
Post by: CPTBadAss on Tue, 29 October 2013, 10:09:24
I don't think an ABS or PBT plate is a great idea. You'd have to figure out what materials would work and see if the 3D printer you have will print that. I believe Matias was the one that said that they experimented with ABS plates and it was too soft. PBT is brittle so a hard strike by accident might chip/damage it; the evidence is with the PBT caps and how they get damaged in the mail if not properly packaged.

People have had varying levels of success with acrylic plates. I'm not a fan but they're definitely an option.
Title: Re: Clasp for Cherry Brown
Post by: Findecanor on Tue, 29 October 2013, 15:54:35
The contoured keywells in the Kinesis contoured and Maltron keyboards are made from plastic, probably ABS.
The key switches are mounted to them, with a flexble PCB/individual wires on the inside.
Suka on this board has made several custom keyboards with 3D-printed contoured keywells, but I am not sure which type of material that he used.

I think that the trick is to make the plate thicker than spec, except precisely where the switch's tabs are.
Also, make perfect square mounting holes 14×14 mm, and make sure that the parts are printed solid.