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geekhack Community => Keyboards => Topic started by: karljs on Fri, 14 September 2012, 21:32:44

Title: Why the difference in activation/reset point on blue switches?
Post by: karljs on Fri, 14 September 2012, 21:32:44
I disassembled a blue switch today, just to check it out, and was surprised to note that the white plastic bits that rub against the metal are not symmetric. I imagine this is what causes the reset and activation points to differ somewhat. Unless I'm wrong, that means it was an intentional design decision, right?

I've always found it a bit of an annoyance and it's one of the main reasons I don't really like typing on blues.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: tp4tissue on Fri, 14 September 2012, 22:34:02
I disassembled a blue switch today, just to check it out, and was surprised to note that the white plastic bits that rub against the metal are not symmetric. I imagine this is what causes the reset and activation points to differ somewhat. Unless I'm wrong, that means it was an intentional design decision, right?

I've always found it a bit of an annoyance and it's one of the main reasons I don't really like typing on blues.

which part are you referring to that's "not" symmetrical.

post pics and circle.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: jeroplane on Fri, 14 September 2012, 23:07:32
^This. Which part do you mean on this diagram:

(http://www.overclock.net/attachment.php?attachmentid=197802&stc=1&d=1298910971)
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: karljs on Fri, 14 September 2012, 23:40:43
Sorry for the poor description. I'm talking about the plastic part touching the spring circled in red.

(http://i.imgur.com/DJeI4.png)

From the angle shown here you can't tell, but there are two tabs that make contact. They appear to have a bump in slightly different places.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: rowdy on Sat, 15 September 2012, 00:10:26
Actually in comparison to the other MX switches, in the blue the white bit is not fixed, and moves of its own accord.  It is when this white bit hits the bottom that the audible click sounds.  Having pushed the key down to make the click, you have to let it all teh way up so the white part can retract, ready for the next downward stroke.

I am guessing what it looks like from your description - maybe the plastic bits are offset to avoid it sticking?
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: dorkvader on Sat, 15 September 2012, 01:22:25
As far as I know, there is Hyserisis (difference is activation and reset points, or a loop in the force curve) present in all audibly tactile switches. They need to get the energy somewhere!

Good theory, rowdy If Cherry did make them asymmetrical on purpose, I bet it's for that reason. I'll have to open up a blue, green, and white again to look at them. If they were asymmetrical, I didn't notice it last time I had one open.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: limmy on Sat, 15 September 2012, 03:52:38
For your information, the asymmetrical shapes of the legs are same for all other MX switches. I am not really sure why they designed them that way, but I am pretty sure there must be a reason for it.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: tp4tissue on Sat, 15 September 2012, 08:52:54
For your information, the asymmetrical shapes of the legs are same for all other MX switches. I am not really sure why they designed them that way, but I am pretty sure there must be a reason for it.

So you're saying the two little nubs sticking out are not symmetrical??

Please circle

Title: Re: Why the difference in activation/reset point on blue switches?
Post by: limmy on Sat, 15 September 2012, 10:29:34
I think the asymmetry is pretty obvious from the pic.. No?
[attach=1]
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: karljs on Sat, 15 September 2012, 11:16:59
I think the asymmetry is pretty obvious from the pic.. No?
(Attachment Link)

Indeed. Limmy's circles are what I was getting at.
Title: Re: Why the difference in activation/reset point on blue switches?
Post by: tp4tissue on Sat, 15 September 2012, 17:04:37
Oh.. that.... Yea the reason for that is because you never hit the keys perfectly square in the middle. So there's always a chance that you hit the keys off center, which means with staggered nubs, there is a higher percentage of times where they will line up, where as if you have perfectly matched nubs, they would almost NEVER line up.