Folks,
Ever since Ray suggested this in the dampening mat thread:
http://geekhack.org/index.php?topic=53792.msg1218289#newI've been talking with a sorbothane app engineer about the possibility of making small landing pads out of 30 OO sorbothane.
1) what is sorbothane?
sorbothane is a an extremely soft, almost gel-like polymer elastomer
http://en.wikipedia.org/wiki/Sorbothaneit is unusual in that it is extremely soft, but has _excellent_ material memory, which means that although it deforms significantly when compressed, it nearly always returns to its original shape as long as the compressive load was not absolutely gigantic.
2) how would it be different from silicone rubber or natural rubber as a landing pad?
well, for one, it is very difficult to make a rubber that isn't actually a messy liquid gel at shore durometers down to 30 OO. here's a quick reference of what shore durometer means, as a rule of thumb:
notice that 30 OO is very close to ye olde gummy bear. yes, a sorbothane landing pad is a lot like putting a very thin gummy bear in your keycaps (but less delicious, i will admit).
3) how much will this cost?
i am currently working on shape, cost and other logistics. however, i am convinced that this item can be made, and it actually feels quite comfortable once you get the geometry, thickness and hardness right. i have samples i have been playing with and what is interesting is that, given the right geometry, you barely lose any key travel. the sorbothane deforms on a hard keypress until it is of negligible thickness and then it pops right back when you release the key.
4) what are the advantages?
it's really the same as any other landing pad, but softer. the idea is that instead of hitting a steel plate and pcb assembly when you bottom your keys out, you hit a very very soft gummy bear that acts almost like a helper spring; this "bottom out helper spring" makes your landing soft, but more importantly, it will react to continued pressing by pushing back very lightly instead of immediately squishing to minimum thickness like silicone or natural rubber.
5) great! i'm sold! let's make these!
unfortunately, there is a problem. the smallest standard size part that sorbothane, the only manufacturer of this material, makes is a 0.5x0.5x0.1" square. i've taken some of these, poked holes in the middle and at this size they are _far_ too large for landing pads. i have been talking to them about tooling up a new tiny mold (won't work), cutting via waterjet (too expensive), and various other things. at the moment, the manufacturing technique they feel is most likely to work is die-cutting large thin sheets. however, we very rarely have items die-cut on GH, and short of moz's die-cutters in india, we don't really have any access with good, inexpensive die-cutting.
6) how can i help?
if you know someone with a very small inexpensive waterjet setup or a die cutting press that will churn out landing-pad sized shapes (from my experiments i'm thinking somewhere around a 0.35" square with a simple pin-hole in the middle. this would work well with the 0.1" material i have samples of. 1mm thin material could be a more traditional 0.4 or 0.45" square, or even a more standard 5/8" OD 3/32" ID o-ring).
that said, i have no idea how popular o-rings and landing pads are these days. i suspect these would be killer with clears or high spring rate blacks, and the thinner material would be perfect for very low spring rate linear switches, like red with 40g-ish springs.
i suspect that they would also feel pretty darn good on topre boards, since the low spring rates on topre switches make bottoming out much more likely.
