40% Keyboards A blog about small mechanical keyboards. Home Firmware Parts Vendors corrects IE6 width calculation Monday, January 8, 2018 The basic unit is a 4x4 matrix with 16 keys. Up to 4 of these can be connected to each other side by side. 4x4, 4x8, 4x12 and 4x16 are possible. There are pads for header pins on each side that complete the circuits from board to board. These can be permanently connected with solder bridges or with pin headers and shunt jumpers. The PCB is a perfect square. Exactly 3 inches square. Standard switch spacing is 0.75 inches, 19.05mm. The header pins are the common 0.1 inch spacing (2.54mm). The Gerber files are on github . The schematic shows how the header pi...