Capacitive keyboard foam pads

[kb2syd]

These are the pads used in the keytronics capacitive keyboard constructions. They were used on the SOL-20, PC, Most pre-pc Tandy computers, etc.

It is a cylinder of foam with some kind of plastic/Mylar skin.

Are there any sources for these still, or do I go to the local hardware store and start messing around.

I tried Mil-Key, but have not gotten any response. I was trying to avoid cannabalizing existing keyboards because these are getting pretty old also.

[mbbrutman]

Mil-Key responded to me earlier this year. I think the owner worked for Keytronic (a large maker of these keyboards) and they either have the old stock of replacement foam or they have the machinery to make new ones. Either way, the quotes price was 75 cents (US) for each key in fairly large lots.

I figured that to do an old Keytronic keyboard up for my PCjr would cost around $75.

Cannabalizing old keyboards will not work because the foam in them is just as old.

My 'one time' fix was to find a similiar density foam, cut to fit, and reuse the capacative material on it. Labor intensive, but it worked.

[kb2syd]

I was thinking of doing the same thing you did. I have 7 or 8 keyboards in need of repair.

Do you recall where/what type of foam you used?

[DimensionDude]

Yow! Seventy-five cents *per KEY*?? I've been ruminating on this problem for a while trying to resurrect the Dimension keyboards. I have some ideas, and it may be worthwhile to persue them.

How many folks would be interested in buying sets of the foam cylinders? I'm reasonably certain that they could be made for less than 75 cents each.

Kent

[mbbrutman]

I used a generic foam sheet that somebody had originally sent me as packing material.

I'm sure there are suppliers of new foam sheets that are designed for similar purposes. I don't know how one 'measures' the qualities of foam, but I'm sure that open-cell vs. closed-cell matters, compressability, how quickly it rebounds, etc.

My foam sheet just seemed to work. It wasn't perfect, but close enough if all we're looking for here.

[kb2syd]

If I could just figure out the qualities. I have an old "repair" kit that I will have to compare with:

http://www.mcmaster.com/nav/framework.asp?ReqTyp=CATALOG&CtlgPgNbr=3308&RelatedCtlgPgs=3308,3309,3316,3319,3320,3321,3326, 3332,3333,3335,3336,3337,3343,3344,3345,3346,3351, 3352,3353,3354,3355,3544&fam=rubberfoam&ppe=1070&ppr=22&psm=2&psl=21&

[gmh]

I just got through fixing a couple of sol-20 keyboards using foam and mylar generally available at hardware and craft stores. I posted a page describing the process at:

http://www.solivant.com/sol20kbd/

[compu_85]

The Lisa also uses this type of keyboard. :(

-Jason

[kb2syd]

Yow! Seventy-five cents *per KEY*??

I've verified this price with the vendor. Minimum order is 100 units. I've also looked at them closely (the ones I have). It would cost me more than $0.75 per to make them (time = money, it has been proven)...

Anyone interested in sharing an order, or adding on to mine? If so, send me a PM.

[mbbrutman]

The materials wouldn't cost that much. I'm assuming that it is your time that is the more valuable part. (If I'm wrong, what did the materials price out at? Do you have a technical description of the foam that is needed?)

The right foam, a standard paper hole punch, and some mylar seems like enough to do it.

My extended Keytronics keyboard would cost $75, which is why it is not done. I'm holding it, but it's not rare or useful enough to do a full restoration like that.

[kb2syd]

It's mostly the time.

Since I can't find the foam already in the right thickness, I'd have to cut it. I don't have a source for the plastic discs (the mylar is easy enough). Finding a punch for a .75" diameter plastic and foam wouldn't be that hard I guess.

The machines I need to repair are not PC keyboards. They are mostly Tandy keyboards from the late 80s. They may be unique in that the disk is about 0.75" in diameter. Most of the descriptions I see refer to discs about 0.25" in diameter.

Then again, I could be wrong...