FROM SWITCH CENTER (FSC)
When discussing the spacings around the edge of the plate, the terminology "from switch center" (FSC) will be used. In that sense, the MX switch cutouts themselves are 7mm FSC, or 14mm x 14mm. The standard plate designs for OLKB are all 12mm FSC - this means the plates come out 2.5mm from the edge of the keycaps. Some 9.5mm FSC plates/cases are also being planned.
GRID SPACING (GS)
The Planck, Atomic, and Matias boards use a 19mm grid spacing (GS), meaning there is 19mm between the switch centers for two normal, 1 unit keys - with this, 1u (unit) can be defined as 19mm. Other common boards (Cherry, etc) have a 19.05mm GS.
View All OLKB parts on github
The 12mm FSC plates are 233mm x 81mm in size and 1.54mm thick (16 gauge stainless steel), with 2.5mm (previously 3mm) diameter mounting holes in the following locations (distances from top left corner when looking down) (x, y):
The PCB was designed to fit into the milled cases - the walls of which start at 8.9mm FSC, and are 3.1mm thick. The inside corner radius of the walls is 6.35mm - this makes the case cheaper to produce, and comes right to the edge of the keyswitches.
3D PRINT YOUR OWN PLANCK PARTS!
View all of the parts on github. (Atomic and other parts are available too)
Adam Forland has kindly proto-printed the Planck bottom using the plans I made for the Planck milled bottom. This 6-piece design turns out slightly better due to ABS's tendency to warp, and can be easily glued together.
The Planck bottom has 1.6mm diameter holes, which are ready to tap with a 2mm/M2 tap for the assembly kits I sell.
The Planck middle piece is designed for use with the regular bottom plate (and top plate), and shares the same side clearances as the bottom piece.