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Model F Keyboard Foam

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evildragon

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So I'm doing a bit of research as I'll have my first Model F keyboard on the way, and I'm watching a lot of restoration videos. A lot replace the foam inside, but some apparently omit the foam now. Is the foam required or not?

So far, my mindset is, if IBM put it there it must be required, so I bought something to use a hole punch with and make holes for a replacement foam. But, if people are restoring Model F's without the foam and have no issues at all (not even sound changes), what does the foam actually do then?
 
I'm in the same boat as you, in the middle of rebuilding one with disintegrated foam. Indeed, the nasty foam is the only reason I took it apart to begin with.

I assume that the purpose of the foam is to take up the slop in manufacturing tolerances and make sure that the black thingies that hold the flipper doodads are pressed firmly against the PCB and don't rattle around.

The last one I did, I used that thin white packing foam sheet stuff and used an empty .45 Auto shell casing for a punch, then snipped out the shoulder with a pair of scissors. (These are both F/ATs; IIRC the XT doesn't have the shoulder bit, right?)

This current one I've been thinking about doing with some kind of piano felt or pipe organ valve leather, for a deluxe cadillac Model F. The kind of keyboard that makes you raise your pinky and drink top-shelf scotch. Yes. But I fear that felt won't compress as much as foam, so it may not work. I dunno. I guess we'll see, when I get 'round to finishing that project. Knowing my luck I'll finish it and then the moths will eat all the felt in a year, lol.

I've never tried one without the foam. Maybe I ought to.

PS: Did you just buy that F/AT on ebay that was stuck on $102 for several days? I had an eye on it, but it went too high for me at the last minute. ;P
 
bladamson said:
PS: Did you just buy that F/AT on ebay that was stuck on $102 for several days? I had an eye on it, but it went too high for me at the last minute. ;P
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Nope that one wasn't me, but I did see it. I was looking primarily at XT versions, which is what I bought. The one I bid on was sitting at around $50 for a few days, then I put in a max bid of $150 (more money than I had, so it's not one of my proudest "charges"). In the end it went up to $123 I think, but it was around $158 after shipping charges. It's now in transit so I hope to see it at least by this weekend, and see how it works before I mess with it. Honestly if it works out of the box without any issues I might not even take it apart.
 
Yeah, if it works I wouldn't mess with it, unless black dandruff comes out when you hit it with the air chuck. D:
 
Do all model F's have foam? Because I have a couple and rebuilt one a couple years back that was super dirty and had rust problems. Took it all the way down to the bent pcb and I dont recall any foam whatsoever, just buckling springs.
 
VERAULT said:
Do all model F's have foam? Because I have a couple and rebuilt one a couple years back that was super dirty and had rust problems. Took it all the way down to the bent pcb and I dont recall any foam whatsoever, just buckling springs.
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Generally yes, they all are supposed to have foam between the barrels and the barrel plate. If there's no foam nor any hint of one being there, then someone may have removed it.
 
evildragon said:
Generally yes, they all are supposed to have foam between the barrels and the barrel plate. If there's no foam nor any hint of one being there, then someone may have removed it.
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I doubt anyone removed it prior to my opening it up but it worked fine without it. I may be remembering it wrong but if we are talking individual pieces (like the compaq portable which I am very familiar with) I didnt come across any. And again worked fine just needed cleaning. May have to re-investigate this.
 
VERAULT said:
I doubt anyone removed it prior to my opening it up but it worked fine without it. I may be remembering it wrong but if we are talking individual pieces (like the compaq portable which I am very familiar with) I didnt come across any. And again worked fine just needed cleaning. May have to re-investigate this.
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No this isn't individual pieces. The foam mat is the size of the entire plate. It's a pretty sizable chunk of Ensolite (the actual brand/type that IBM used). You can see a picture of the foam here: http://www.brimstudio.org/2013/10/ibm-model-f-restore/

I seriously have never seen a Model F sold without one. Even the one I just bought on eBay has some internal pics and you can see the foam sticking out at the top. Sometimes they are white, sometimes they are black, IBM has used both colors.
 
Al Kossow said:
page describing the use of polyethylene instead of polyurethane foam
https://deskthority.net/viewtopic.php?t=11657
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Look down though towards the bottom of his post where he shows examples of the typing output using ethylene, it induces ghosting and chatter like you've never seen before. I'm assuming from the fact that ethaline is messing with the capacitance of the PCB itself.
 
My Model F arrived. Somehow the foam is actually fine. I have no idea how 35 year old foam is still intact. But I'm going to just "leave it".
 
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