O-rings of unusual size

[Cataphract]

I have been using 3mm thick, 5mm ID 70A o-rings for quite some time now. I have been hankering for something softer but have failed to find anything in this size. 70A does nothing at all to reduce noise. 3mm may come as a shock; from searching I only see max 3/32" or 2.5mm in group buy threads. But it halts travel almost immediately after actuation on my keyboard (Filco w/ MX Browns) which I rather like. You might say that I'm after a "mechanical scissor" switch, one with laptop-like travel but lighter to press and durable.

So I turn to you guys. How might I go about acquiring a softer set of rings?

[Photoelectric]

From personal experience, I really like 50A black o-rings from Amazon.com in terms of dampening the bottoming out sound and having a small bit of travel reduction.  Had great results with them with MX Browns on my first keyboard.  I don't use o-rings on my current keyboard with MX Browns--really like the full travel distance on my Ducky.
http://www.amazon.com/dp/B0051XWXCE/ref=biss_dp_t_asn

[Cataphract]

Ah, I'm sorry but 3mm is almost twice as thick as those 50A 1/16" rings. I guess I could try stacking them though...

Would you happen to know of a 40A or softer ring that size? I can hardly find 40A at all from online outlets, let alone in keystem size.

[Photoelectric]

Stacking them would prevent your keycaps from fitting on properly.  I would still give them a try at some point.  $8.25 is fairly cheap vs. other o-rings (like from WASD).  I've tried IMSTO's silicone o-rings, which are probably like 40A, and did not like either size.  The large fat size, which is something like 2.5mm thick, actually doesn't help with bottoming out noise because the inner thickness is not enough. The o-ring gets thick too far out from the center.  They are good for some very specific keys, but I'd not advise them for standard OEM keys with crossbar support.

[Cataphract]

So 3mm thick 30-50A rings would have negligible effect on noise versus 70A? If so then I'll just stick with my loud key slapping.

[TimIsABat]

Stacking them would prevent your keycaps from fitting on properly.  I would still give them a try at some point.  $8.25 is fairly cheap vs. other o-rings (like from WASD).  I've tried IMSTO's silicone o-rings, which are probably like 40A, and did not like either size.  The large fat size, which is something like 2.5mm thick, actually doesn't help with bottoming out noise because the inner thickness is not enough. The o-ring gets thick too far out from the center.  They are good for some very specific keys, but I'd not advise them for standard OEM keys with crossbar support.

poop I'm waiting on these from IMSTO

[Photoelectric]

Stacking them would prevent your keycaps from fitting on properly.  I would still give them a try at some point.  $8.25 is fairly cheap vs. other o-rings (like from WASD).  I've tried IMSTO's silicone o-rings, which are probably like 40A, and did not like either size.  The large fat size, which is something like 2.5mm thick, actually doesn't help with bottoming out noise because the inner thickness is not enough. The o-ring gets thick too far out from the center.  They are good for some very specific keys, but I'd not advise them for standard OEM keys with crossbar support.

poop I'm waiting on these from IMSTO

Well, maybe they'll be okay for your caps.

[Topre]

How do Cherry switches even work with o-rings thicker than 2mm? I thought the actuation point was at 2mm and if you had a thicker o-ring then shouldn't the contact points be unable to contact?

[Johan]

Its rubber so it should squish to a point where it registers.

[fohat.digs]

My daughter had a bag of dental rubber bands left over from her braces.

To my fingertips, these feel thinner and softer than any of the typical O-rings I have tried.

[Topre]

Its rubber so it should squish to a point where it registers.

Yes o-rings are silicone, but most silicone does not compress from 3mm to less than 2mm. The thickest o-rings that WASD Keyboards sell are 0.4mm, which are more 2.6mm thinner than 3mm o-rings.

[Photoelectric]

Its rubber so it should squish to a point where it registers.

Yes o-rings are silicone, but most silicone does not compress from 3mm to less than 2mm. The thickest o-rings that WASD Keyboards sell are 0.4mm, which are more 2.6mm thinner than 3mm o-rings.

I don't think you have your units or numbers correct.

[Topre]

Its rubber so it should squish to a point where it registers.

Yes o-rings are silicone, but most silicone does not compress from 3mm to less than 2mm. The thickest o-rings that WASD Keyboards sell are 0.4mm, which are more 2.6mm thinner than 3mm o-rings.

I don't think you have your units or numbers correct.

I also didn't think they were only 0.4mm thick, but I highly doubt they are thicker than 2mm. I'm getting these numbers straight from WASD Keyboard's site. A 0.4mm reduction should mean a 0.4mm o-ring.

Unless if you slam on your keycaps, I don't understand how keys will register with 3mm thick o-rings.

[Photoelectric]

The O-rings are donut-shaped.  It means that they have a varying thickness profile.  If you imagine their cross-section as a circle, going from the keycap stem outwards, their thickness will grow and then diminish.  The location of the maximum thickness is determined by 1. inner diameter of the "donut hole" and 2. the diameter of the "donut's" cross-section. 

The underside of the keycaps hits the bottom of the switch stem to make the bottoming out noise.  The larger an o-ring is, the more exposed and less padded the inner circle becomes.  The O-ring of 1.2mm maximum thickness can reduce travel distance only by a fraction of that thickness, because of the thickness decrease toward the keycap stem. 

 I think an ideal o-ring would have a uniform square / rectangular cross-section to work with all kinds of keycaps.  But then there exist landing pads, so maybe those are what the OP really needs.

[Topre]

Actually I figured out why, I had translucent low profile keycaps that would touch the top of the switch casing. With regular keycaps there is more than just 1mm of room between the top of the casing and the keycap itself, not including the stem. That means 3mm o-rings would not have worked for my low profile keycaps, but would have been fine for my regular keycaps.