High Profile Dimension Questions

[Umio1]

I'm in the process of designing a High Profile keyboard and need to confirm some of the design decisions:

1. Distance from the edge of a switch plate hole to the boarder wall. Switch holes tend to be 5 mm apart, so i divided that by 2 and added 0.5 mm to get a distance from switch hole of 3 mm. Will 3 mm be enough clearance for keycaps?





2. Distance from the top of the switch plate to the top of high profile top plate. I looked at some open source high profile keyboards and found them around 6-7 mm; whats the typical height from the top of a switch plate to the top of the outside boarder wall?





3. I'm looking for a standard on how much space can be left between the tip of a drilled hole and the other side of the part. I'm trying to mount a piece on the back of the keyboard and need to drill mounting holes in the back of it; I'm planning on using 4 2m screws but am unsure how deep i should go as to not dimple the other side.




4. Is there any other way I can mount a brass plate to the back of the keyboard if using screws doesn't work? There's 2mm of clearance between the PCB and bottom of the keyboard, and the bottom of the keyboard is 2.5 mm thick and don't plan on making the thickness past 3 mm. trying to brainstorm some low profile mounting methods for the minimal space.

[fpazos]

Edit: I was wrong, listen to
dingusxmcgee

[dingusxmcgee]

For 1 and 2 I would say 3.025mm(this gives you enough room that it doesn’t look like a wide gap and allows you to still fit a switch puller in between) and about 7.5mm. You can go a little higher like 7.6 or 7.7 but get some switches/caps into your design and align it and you’ll be able to see for yourself how it looks.
Not sure on the others.

[dingusxmcgee]

For brass plate mounting, maybe thin magnets?

[Umio1]

For brass plate mounting, maybe thin magnets?

I was thinking about that; may have to if i cannot find anything more semi-permanent

[mike-y]

For keycap clearance, I like to use a 20mm square for each single keycap. you can go a bit tighter, but it gets hard to remove the keycaps, as the wire puller doesn't fit between the cap and the case well.  and you'll have less "wiggle" room if something doesn't line up perfectly. My method is to find the centerline of the top row of switches, and offset 10mm to get the inside edge of the case.   You can go a bit more or a bit less to suit your preference.

For high profile height, I've been using 7.5mm from the top of the plate.  less than 7mm will sometimes show a tiny gap at the bottom of the keycap.

I'm also leaving 3mm between the bottom of the plate and the case.  You might be able to get away with 2mm, but some of the components on the bottom of the pcb could hit the case.  If it's plastic, it's no big deal, but if you have a metal case, it can cause a short.

 

[Umio1]

For keycap clearance, I like to use a 20mm square for each single keycap. you can go a bit tighter, but it gets hard to remove the keycaps, as the wire puller doesn't fit between the cap and the case well.  and you'll have less "wiggle" room if something doesn't line up perfectly. My method is to find the centerline of the top row of switches, and offset 10mm to get the inside edge of the case.   You can go a bit more or a bit less to suit your preference.

For high profile height, I've been using 7.5mm from the top of the plate.  less than 7mm will sometimes show a tiny gap at the bottom of the keycap.

I'm also leaving 3mm between the bottom of the plate and the case.  You might be able to get away with 2mm, but some of the components on the bottom of the pcb could hit the case.  If it's plastic, it's no big deal, but if you have a metal case, it can cause a short.

10mm from the center-line ends up being 3mm from the edge of the cap so that works out perfectly, thanks for the feedback. as for the 2mm clearance I've got a low profile board i made using essentially the same PCB with ~2mm clearance, the lowest part is the USB-C which is a fraction of a mm from bottoming out so it all works out.

[Jefff]

For brass plate mounting, maybe thin magnets?

I'm not sure if brass is magnetic, but I guess you could put neodymium magnets in the case?