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IBM Model F PC/XT disassembly

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JBert:
Interesting to finally see one disassembled (and quite courageous of you, seeing how I read other reports in the manner of "don't even think about it").
Is there really no way to take it apart more easily? I was thinking of securing the cap-less spring and rockers with some metal wire so they wouldn't fall out once the plates are separated.


Also, I was wondering: did you find a way to un-stiffen the space bar? I have the habit of pressing the spacebar with the tip of my thumb. When I dusted off the XT and tried to type some stuff with it, it did strike me as annoying. Pretty sad actually, all the other keys seem to work great...
Of course, learning to press it some other way on it is still an option, were it not that habits are hard to change.

ch_123:
I've been told (by Sandy) that removing the space bar on the Model F is a bad idea, as reinserting it would require disassembling the whole assembly. I assume that is true for the XT Model F as well as the AT one. If you want to do so, Chloe's guide is a good reference, but I'd just try to get used to it. It is definitely one of the weaker points of the Model F design.

chimera15:
The keys are partially melted too.

ch_123:
Took mine apart earlier on to give it a much needed clean, found this guide invaluble for fixing it up. Some interesting things I noticed on mine - one is that there are contacts that would in theory allow you to turn it into a more Model M like layout (there are contacts on each end of the space bar which would correspond to the location of the alt keys, one between shift and z for the \| key on an ISO layout, and one for the same key on the ANSI layout is covered by the large enter, as is a contact for the #~ button on the ISO layout) but none of them do anything you complete the circuit. I'd be very interested to know if someone knows a way to "enable" them, but I wouldnt count on it.

I also tried to figure out what exactly it was that gives Model F their distinctive feel over a Model M. I was thinking that it might have been something to do with it striking a capacitive switch instead of a membrane, or something to do with the spring/hammer. I assembled a test switch (unlike the model M, the little shafts which house the springs are removable) and tried it on different surfaces. The surfaces affected the amount of flex I felt, but not the feel of the switches, so I guess it's either because the F has a different type of spring, or the different shape of the hammer somehow impacts the tactility of the keypress. Because there is less resistance required to press the key, I'm thinking it's the spring.

EDIT: If the A01 springs in Chloe's pics are the same length as the Model M's ones, then the fact that they are shorter than the Model F's would probably explain it. Goo on Unicomp, put longer springs in your boards!

msiegel:
besides a softer spring on the model F, the springs seem to buckle later in the keystroke.  i'm more likely to bottom out on the F, but only lightly because the buckling action is smooth and crisp.

the F also doesn't have a rubber sheet under the hammers, so there's less damping.

it would be fun to move those key-modules into a more modern arrangement, if a matching upper plate and pcb could be fabricated :)

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