Replacing the soft square CUSHIONS under Spacebar

[JDW]

Below are photos of my 5126 Macintosh Portable's Keyboard with ALPS ivory switches. (Closeup photos below show more yellow than reality. They are ivory.)

Note the SQAURE PADS on either side under the spacebar. The ends of that metal support bar hit the pad rather than smack the metal frame beneath. I removed the pads due to age. There's "2mm thick" foam tape on Amazon, but is 2mm too thick? Not sure what the original thickness was. Would love to hear your advice and experiences.

Here's an example of 2.0mm thick foam pads (tape on one side).

I did Google the matter but I'm only finding a scant amount of info on the subject, and the info I find is questionable. In this forum post, "Hypersphere" claims to have used "0.15mm" thick replacement pads, which is ridiculous! Paper is about 0.1mm thick for goodness sake! He might have meant 1.5mm, but there's no way to confirm as that was posted in 2016.

 

[YMK]

You could try Tesa tape: https://www.amazon.com/Tesa-Fleece-Interior-Harness-Mercedes/dp/B00NN6B9R6

I measured 0.28mm thick.

 

[JDW]

@YMK
Thank you for the advice. I actually have automotive tape in my parts inventory!

However...

Close observation of my closeup photos show that the original cushion Apple used was open-cell, low-density foam, which is very soft and highly compressible. I believe I'm right about that.



So the question then is, how tall/thick was it originally? About the thinnest I can find on Amazon is 4.8mm thick:

Amazon.com

 

[JDW]

@YMK
I wish to thank you. Your kind suggestion of using automotive tape was the best solution in the end.

What I did was determine that some soft-side velcro I already had in my possession was shorter in height than any open-cell foam I could find on Amazon, so I tried that. And it didn't work. The spacebar didn't go down enough, even though the velcro was only 2mm tall!

I then removed the velcro and added the thin automotive tape. Perfect! It is very think yet the ideal height. You don't get the feeling your key is not going down all the way, and because it is soft, the key bottoms-out by hitting that tape, instead of the hard metal beneath. The ideal dampener! I liked it so much I added it under all the keys which have a support bar, making them much quieter too!



I hope this info helps everyone else who wants to refurbish or even clean their vintage Apple keyboards with ALPS keyswitches.

Also, I soaked and then individually toothbrush-cleaned all the keycaps in 55°C hot water with a lot of hand dishwashing liquid mixed in. I also de-yellowed the spacebar, which is made of a different plastic than the keycaps, and is why the keycaps on the Portable don't yellow. I used normal 3% H2O2 and only a tiny teaspoonful of powdered OxiClean in a transparent plastic container (no added water), placing it outside all day in the sun (not overcast) with Saran Wrap on top of the container to keep the H2O2 from drying out. Before adding the H2O2, I slipped a couple angled pieces of metal in the two plastic supports on the bottom of the spacebar (the ones which grab the metal support bar on the keyboard), taping the metal pieces to the bottom of my plastic container with masking tape. That little trick held the spacebar firmly in place from 8am to when the sun went down at 5pm. The end result was a perfectly deyellowed spacebar that did not turn white — it retained its natural color. Photo below.

 

[pocketscience]

With my car hobby I have a good supply of Tesa tape so will be giving my Portable keyboard similar treatment I think!