Reliable smaller than Cherry MX keyboard switches fdor custom keypad

[Jester]

I'm going to make a custom keypad for a piece of machinery. I was thinking of using Cherry MX low profile switches, however it seems like the minimum cap size is about 18mm x 18mm and I think the actual switch dimensions are about 14 x 14mm. I'm tight for space so looking for something smaller.

I have some sort of generic numeric keypad with perfect sized buttons about 8.25 x 7.3mm (see below) these would be ideal however I have no idea what switches are used in it.

All suggestions welcome. In a perfect world I would like to be able to print the caps

[ajb]

How close together do you need the switches to be?  That's what really determines the max switch dimensions.  You could certainly put small 8x8mm or whatever keycaps like that on a cherry MX, for example, as long as the caps are >14mm center-to-center.

At a guess from the picture, that keypad probably uses a sheet of rubber domes on top of a PCB for the switch.  The underside of the dome would have a conductive pad, which comes into contact with pads on the PCB below it when the button is pressed.  If you can find a keypad with the right layout of buttons, you may be able to print replacement keycaps and reuse the sheet/domes/PCB. 

Other than that, there are tons of switches out there, all sorts of shapes and sizes and styles, so it's hard to give a recommendation without more info.  Do you care about tactile feel? Sealing?  Do you need an off-the-shelf keycap (not available for many switches, so this would limit your options)?

[tooki]

All suggestions welcome. In a perfect world I would like to be able to print the caps

As in printing legends onto the keycaps, or 3D printing the keycaps themselves?

There exist tons of switch options, but as others said, you need to specify your requirements. What are your reliability requirements? What about environmental conditions? (Cherry MX are not that great in dirty environments.) Typical usage? (For example, the fairly light touch of a Cherry MX can be a liability if accidental pressing is a concern.)

[aeberbach]

Gateron KS-33 switches require a 14mm square plate cutout (same as regular MX) but are just over 12mm from bottom of locating pin to top of plunger, so significantly lower. Make a printed plate with 1mm between each switch and you would have a keypad around 61mm square. You could print the standard MX-stem caps for these.

[Jester]

How close together do you need the switches to be?  That's what really determines the max switch dimensions.  You could certainly put small 8x8mm or whatever keycaps like that on a cherry MX, for example, as long as the caps are >14mm center-to-center.

At a guess from the picture, that keypad probably uses a sheet of rubber domes on top of a PCB for the switch.  The underside of the dome would have a conductive pad, which comes into contact with pads on the PCB below it when the button is pressed.  If you can find a keypad with the right layout of buttons, you may be able to print replacement keycaps and reuse the sheet/domes/PCB. 

Other than that, there are tons of switches out there, all sorts of shapes and sizes and styles, so it's hard to give a recommendation without more info.  Do you care about tactile feel? Sealing?  Do you need an off-the-shelf keycap (not available for many switches, so this would limit your options)?

12mm  center to center would work, so just a bit smaller than the Cherry MX

Fairly clean environment, this will be out of the swarf path.