Making perfect Keytronic replacement keypads from Al Kossow on 2013-09-17 (lisalist1)

From: Al Kossow <aek_at_email.domain.hidden>
Date: Tue, 17 Sep 2013 17:06:21 -0700

I had to fix some Lisa keyboards, and here is what I finally came up with after a week or two of experimenting that produces perfect pads.

Woodland Scenics 5mm HO track bed for the foam, as others suggested ($1 for 24" x 2") Maudlin PL10-0075 .0075 x 10 x 20 plastic shim stock for the back (about $10 with shipping) Michaels metalized mylar sheets for the pads (a couple bucks for several square feet)

Get a
Disc Cutter with 7 Punch 1/4" to 5/8" from ebay ($28) http://www.ebay.com/itm/390617394797 for example This is critial (see below)

Cut the foam and shim stock to 10" x 9/16" Cut strips of mylar long enough and wide enough to apply to the foam

Attach the shim stock to the mylar with Scotch Super 77 spray adhesive Do the same with the mylar, metal side against the foam, with enough tension so it is smooth. You only have about a second to fiddle with the mylar before the adhesive starts to set!

Shim the disc cutter so the strips just fit through the upper and lower plates without binding.

Then use and arbor press or non-metal mallet to punch the discs, mylar side up. You'll get about 15 discs per strip. I experimented with a leather punch, and even tried a 11mm cigar punch, but the only way I could get perfectly straight cuts through the foam was with the disc cutter.

So far, I've identified the following systems that need pad replacements

Apple Lisa
Corvus Concept
Terak
Genrad Futuredata
SOL-20 I was thinking of making a bunch, but changed my mind after finding what a PITA they are to make.

The other thing I discovered was Elmers School Glue Sticks work the best for attaching old pads and plastic to new foam. Received on 2013-09-18 10:25:17