18 Jan 2017, 09:28
B2R accepts a two-pin LED (single colour), while B3K (Romer-G) simply provides a cavity for a surface mount LED, which can be RGB (four-terminal). B3K then provides a light pipe to bring the light up to the keycap level; this does not move. The B3K design untangles the switch from the lighting implementation, while with Cherry MX you're officially tied to single-colour LEDs. Many Cherry MX clone switches allow a wide four-terminal LED to utilise all four holes (inner LED holes and outer diode/jumper holes) by making the switch slot long. Cherry themselves did the same thing as Logitech/Omron and allow an SMD LED to sit within the switch. Matias switches are similar but the LED has to go on the back of the PCB.
B2R is of course a reed switch. B3K has what seems to be a unique design where a single pair of contacts provides two sets of contacts, so from the outside it's one SPST switch, and from the inside it's a pair of switches, the idea being I assume is that if one side goes jittery (leading to chatter), the other side will function normally and conduct while the other side is bouncing: the bounce won't be detected by the keyboard controller.
B3K is tactile. Not very tactile, but the tactility is there. B2R is 100% linear — being a reed switch, you can't even feel the contacts engage. At least one switch would emit a faint click, but by and large the only sound you hear is scraping (they may be worn, as when new I'd expect them to be much smoother and quieter).
B2R is both downstroke and upstroke damped, using two very different approaches. The downstroke damping uses a rubber pad pressed onto the bottom of the slider, and the sides of this collide with posts inside the switch. The upstroke damping uses a "waistband" around the middle of the slider, with a protrusion that catches on a downwards-facing ledge inside the shell.
Detailed pictures of B3K are on the wiki. More pictures of B2R will follow, although there's not a lot to see as the shell doesn't come apart and it's hard to see inside. The additional pictures will be of more use in demonstrating the damping, and the off-centre return spring. The action (the reed module) is already covered (not a great photo, as it was at the very edge of macro depth of field).
Both switches are notable for being quite unlike anything else on the market, and neither one is anything remotely like the other. They are both comparatively light though, and B2R in particular should in theory feel superb when new. If Mr.Nobody manages to get hold of new ones, maybe we'll find out. (There's also five on eBay, but I won't use eBay.)
I want one now. There are tons of Fanuc key pads on ebay with these and with a slightly different looking switch.
