What's all that about keycap profile and travel distance?

[spiceBar]

I appreciate the info as well! What o-rings are you using though? And how come you identify them only by colour? (I geniounly wonder, I'm not being snarky.) Have some sort standard for o-rings and colours developed in the mechanical keyboard community, or what? I'm asking since the o-rings that WASD sells are blue: 5 mm diameter, 1.7 mm thick and red: 5 mm diameter and 1.5 mm thick (as per e-mail correspondens with one of the empoyees). And the blue they sell are the same size, however slighlty softer than the black rings they sold previously, I think. However, looking at Keyboardco's website, the o-rings that they sell (they only sell one size) are red and 2mm thick. At least that is what they say.

I have purchased several bags of red O-rings from the Keyboard Company, and as far as can tell they are approximately 1.5mm thick. They are relatively soft, I think they are 40A.

I have tried stacking two of them in a Filco Majestouch 2 TKL with browns are the keys were still usable. They had naturally a very short travel, but still worked. I know it doesn't make much sense, but it did not prevent key actuation.

In any case, with just one installed per key, they do a very good work of dampening the sound without changing too much the mechanical feel. The bottoming out doesn't feel too mushy either.

I have also ordered the blue ones from WASD. I may report on them when I get them, probably next week.

That's interesting, thanks! So the 2mm thickness that they claim the o-rings to have, is actually wrong? Did you use a caliper when measuring? If you're right, it seems like the (red) o-rings that The Keyboard Company sell are the same as the red ones that WASD sell (thought they could still be made of a different type of rubber, I suppose). That's good to know.
Please do write a few words about the blue WASD o-rings when you get them, that would be appreciated.
I don't have any o-rings myself yet, but I do intend to get some. I'm just not sure wether to get the blue or red WASD ones (or something of the same sort elsewhere).

I did not use a caliper, I don't have one.

I have used a ruler, and it's very clear that they are well under 2mm. To my eyes, exactly between 1 and 2mm. So yes, the numbers from the Keyboard Company are simply wrong.

Actually, these O-rings are almost always get wrong measurements from the companies that sell them. For example, WASD claims that their red ones have a 0.2mm reduction travel (=thickness) and the red ones have 0.4mm reduction travel. It does not make any sense. I think the red ones are around 1.5mm thick and the blue ones 2mm.
  http://www.wasdkeyboards.com/index.php/cherry-mx-rubber-o-ring-switch-dampeners-125pcs.html#ad-image-0

So before purchasing any O-ring, it's a good idea to check here on Geekhack what others say about them.

Hint: if you order O-rings, purchase several types. An O-ring bag is generally less expensive that the shipping fees...

I answer to my own post because I have said something stupid and I can't leave it as is.

The width of the O-ring is definitely not the same as the travel reduction.

It all depends, as pointed out earlier in this thread, on the clearance under the keycap when the switch bottoms out.

More precisely, it depends on the space between the bottom of the crossbars and the top of the switch housing when the switch is in the "bottomed out" position.

If this space is 1mm and the width of the O-ring is 1.45mm, then the travel reduction is 0.45mm.

So a travel reduction of 0.2 or 0.4 mm is perfectly possible with 1.5 or even 2mm thick O-rings, and I stand corrected by myself.

This makes an even stronger case for the advice of purchasing several types of O-rings, as it is really difficult to tell in advance the reduction you will get from a given type of O-ring. This gets even worse if you mix several keycaps types on the same keyboard, as the clearance below the keycaps may vary. To compensate, you may need several O-rings types.

[RockSteadyYeti]

I am still a little confused after reading your great guide. I have a Filco M2 Camo with black switches, what size o-ring would I need to minimize the travel as much as possible while still having a switch that works and caps that stay on? First timer with Mech keyboards, thanks in advance for any insight!

[swill]

I am still a little confused after reading your great guide. I have a Filco M2 Camo with black switches, what size o-ring would I need to minimize the travel as much as possible while still having a switch that works and caps that stay on? First timer with Mech keyboards, thanks in advance for any insight!

You have keycaps that are considered OEM (they are taller than Cherry).  The switch has a travel distance of basically 4mm.  I tend to like a minimal travel reduction while still giving good dampening.  I personally like a travel distance of 3.5mm with o-rings.  I achieved that with an o-ring that was 1.75mm thick.

You are looking for basically the minimum travel distance you can have with OEM caps.  I have tested this only with Cherry keycaps.  With Cherry, I use a 1.45mm o-ring (small from IMSTO) to achieve the 3.5mm travel distance that I like.  When I used the 1.75mm o-rings with Cherry, I had a 3.15mm travel distance.  The switch still operated, but it was VERY close to the key activation on my MX Browns.  I don't think you can do less than 3.15mm and have a reliable key activation.  Also, the key caps do not go all the way on when you have 3.15mm travel distance.  I was not concerned with the caps coming off, but I definitely realized they were not on all the way.  I would recommend you use the softest o-ring you can find if you are going to try to limit the key stroke distance as much as possible.  This will allow you compress the o-ring a bit when you apply the keycap and the cap will go on farther.  Also, I think the softer o-ring will be more comfortable with this setup.

So if I do some math here I would deduce you would need the following to limit the travel distance as much as possible with OEM while still having a functional switch.
Cherry:
3.5mm travel => 1.45mm ring  |  3.15mm travel => 1.75mm ring
  1.75mm - 1.45mm = .3mm  |  3.5mm - 3.15mm = .35mm
  The keycap now goes on .05mm less which accounts for the difference between .35 and .30

OEM:
3.55mm travel => 1.75mm ring  | 3.15mm travel => X ring
  1.75 + .3 = 2.05mm  |  3.55mm - 3.15mm => .4mm

This is not an exact science here.  There was probably about a .05 margin for error with the measurements.

I think I would recommend 2.05mm o-ring or there abouts to reduce the travel distance as much as possible.  I am tempted to say 2.10 because of the numbers, but I personally found this to be really uncomfortable, so if you have not tried it, I would error on the side of a bit smaller than you think, so I will stick with 2.05 as my suggestion.

I have not seen o-rings of that size (personally, if you want to sent me a couple and you know there source I can do tests).  The o-rings I have seen/tested are the ones in this picture.  I can test the 1.95 with an OEM cap if you want...



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