Greetings!
While the GH36 Matrix Keypad and the Nuclear Data Green keycap group buy (and recently, the JD45 PCB layout) have taken my time away from the GH-122/154, I have
not forgotten! In fact, you should all take comfort that I am using those lesser boards to aid my learning curve as I work my way up to the battleship that is the one and only
GH-122.
Rhetoric aside, I now have the aforementioned Nuclear Data Green keycaps, and it is clear they need a proper home, so I spent some time the last couple of days working on the GH-122. Specifically, I took some detailed measurements of the Unicomp PC-122 case to work out block spacing for the GH-122 PCB.
Unicomp PC-122 block spacing of 0.350"The blocks are 0.350" apart, with 0.280" separators. These dimensions are simple to bring into the GH-122, enabling the PCB to fit into the $20 Unicomp case. However, what isn't so simple is the fact that the Unicomp (i.e. IBM-designed) case is designed for a curved keyboard, and so the opening is
taller than normal, and of course it is concave, making the actual arc even longer.
On a flat plane the main blocks are 3.997" tall (I am using 4.000" for the design) but an MX keyboard block is only 3.750" tall. That leaves us with an extra 0.250" of visible gap above and/or below the keycaps. I cannot make a curved PCB (well, I can, but I am not going to!) but I
could distribute the extra space between the rows. This turns a quarter-inch gap into four invisible 1/16" gaps.
So here is the question:
Should I add 0.0625" spacing between the rows? It won't affect how the PCB looks, and it will enable it to better fill the openings on the Unicomp PC-122 case. And any custom plates and cases can have the same spacing as the PCB, so that will be fine as well.
What won't be fine is that every designer will have to remember that this PCB has that extra spacing, and that the 0.750" square grid is stretched vertically into an 0.750 x 0.8125" grid. This will be especially important for 2x vertical keys like ISO Enter and the pair on a numpad.
TL;DR Should I add an extra 1/16" between rows to make the PCB fit better in the PC-122 case? - Ron | samwisekoi
Sig auto-typed by my GH36 LH keypad.