|Re: Halfnut mushy keys|
Message #3 Posted by Randy on 4 Feb 2008, 1:33 p.m.,
in response to message #2 by Raymond Del Tondo
Units that have "mushy" keyboards is due to a manufacturing change.
There is a rubber sheet that lives between the keytops and the key snap domes underneath. This provides some quieting and mechanical dampening of the metal snap domes.
Originally, that rubber sheet was 0.016" (0.4 mm)thick. Over time, it was learned that the keys began to actually puncture the sheet and as a result, some keys would sit a bit lower than others. When the halfnut redesign came along, they doubled the thickness of that sheet.
With the 0.032" (0.8mm) sheet in place, the keys have to press through double the thickness of material to actuate the snap dome, making them feel what most call "mushy". Solved one problem, got another...
It is interesting to note that some early halfnuts had the thinner sheets installed, no doubt as an effort to use up existing stock on hand. No, I can't give you a specific serial number range of when the change over occurred :(
Between the fullnuts and halfnuts, the actual switch components have not changed, only that rubber sheet. The only change to the keytops was the early 41C "tall key" variant. They were the same slope as the earlier 30 series keys. It is also common in the early "tall key" models to have poor tactile feedback of the 1 & 2 keys. Changes to the heat stakes and the elimination of the circuit board hold down nuts corrected the problem.
Edited: 4 Feb 2008, 1:43 p.m.