OP, I'm currently typing on imsto thick PBT caps with O-rings right now. Refer to the pic on the bottom. On standard thickness caps (ABS or PBT), I use O-ring size "E" because it purposely decreases the bottom-out distance so I can type a tad faster. In order to keep this same feel and bottom out distance, I'm using size "A" on the thick imsto caps right now. You're probably using size "A" right now on your standard caps, so if you want to retain this same feel, you'll need to find O-rings in size "D" because the stems on thick PBT caps are too short and will change the feel too much (bottom out distance) if you use the same O-ring size as your normal caps.
With O-rings installed, you can still feel the difference between material and thickness, but it's just that the noise is dampened and bottom-out distance is also shortened. I still have a pack of size "D" left so PM me if you're interested in those.
Show Image
(http://img.photobucket.com/albums/v288/WhiteFireDragon/keyboard/Orings-2.jpg)
Nice chart bu I could never stand something like E on my caps
OP, I'm currently typing on imsto thick PBT caps with O-rings right now. Refer to the pic on the bottom. On standard thickness caps (ABS or PBT), I use O-ring size "E" because it purposely decreases the bottom-out distance so I can type a tad faster. In order to keep this same feel and bottom out distance, I'm using size "A" on the thick imsto caps right now. You're probably using size "A" right now on your standard caps, so if you want to retain this same feel, you'll need to find O-rings in size "D" because the stems on thick PBT caps are too short and will change the feel too much (bottom out distance) if you use the same O-ring size as your normal caps.
With O-rings installed, you can still feel the difference between material and thickness, but it's just that the noise is dampened and bottom-out distance is also shortened. I still have a pack of size "D" left so PM me if you're interested in those.
Show Image
(http://img.photobucket.com/albums/v288/WhiteFireDragon/keyboard/Orings-2.jpg)
Wow, thanks - that was extremely informative. Just to clarify, the o-ring difference you mention isn't dependent on the actual keycap thickness, but is due to the lower Cherry profile of the caps, correct? (So what you say applies to any Cherry profile caps, not just imsto thick)
Also, is there a conversion chart between the sizes of each of those o-rings in those letters to inches? I've been using these 008 ones from Amazon, which provided a nice big table of the o-ring measurement specifications for each product:
http://www.amazon.com/008-Buna-N-O-Ring-Durometer-Round/dp/B0052AU0HQ/ref=sr_1_1?ie=UTF8&qid=1347998514&sr=8-1&keywords=o-rings+buna+008