Replacement Foam Mat for IBM Model F Keyboards?

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wcass

20 May 2014, 23:13

The Kishsaver pattern was posted below. This one is the AT pattern. I can't seem to find my XT pattern, so i guess i'll just have to recreate it. I will post it in this thread when i do that.
Model F AT pad.pdf
(41.6 KiB) Downloaded 162 times
This has markings for the extra barrels left and right of the space bar - only cut those two barrels out if you have added them.

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vivalarevolución
formerly prdlm2009

21 May 2014, 04:30

wcass wrote:
prdlm2009 wrote:Wcass, have you experimented with different types of foam you can order from McMaster and found out the one you linked is the best for this application? I noticed that they have lots of options.
I have very little experience actually. I knew that i needed something thick enough to fill the wider spots but it needs to compress down for the tight spots. I filtered for "extra soft" or "soft" and that left me with just two options (excluding buying full rolls) - the stuff i linked to and silicone foam. The silicone was 10x as expensive, so I just went with neoprene.
Thanks. What I have been wondering is if 1/16 of an inch is thick enough. It just seems to thin.

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Hypersphere

21 May 2014, 14:20

prdlm2009 wrote:
wcass wrote:
prdlm2009 wrote:Wcass, have you experimented with different types of foam you can order from McMaster and found out the one you linked is the best for this application? I noticed that they have lots of options.
I have very little experience actually. I knew that i needed something thick enough to fill the wider spots but it needs to compress down for the tight spots. I filtered for "extra soft" or "soft" and that left me with just two options (excluding buying full rolls) - the stuff i linked to and silicone foam. The silicone was 10x as expensive, so I just went with neoprene.
Thanks. What I have been wondering is if 1/16 of an inch is thick enough. It just seems to thin.
I hope not -- I have just ordered both silicone sponge and neoprene foam in the 1/16-inch thickness. However, the much less expensive art foam is a bit thicker at 2 mm. It will be some time before I tear down my Model F keyboards, but I will try the various foam replacements and come back with a post on what appeared to work best for me.

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Game Theory
Mr. Despair

21 May 2014, 14:27

The only reason I chose silicone over neoprene at the time was the silicone has reportedly less of a smell. Though I do not think either are bad.

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vivalarevolución
formerly prdlm2009

21 May 2014, 19:16

I have the 2mm art foam in my Model F 122, and I fear that it might be too thick in some places. I think it is preventing a couple springs and hammers from shifting between the on and off position, if you know what I mean.

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vivalarevolución
formerly prdlm2009

22 May 2014, 03:03

Got some keyboard science on the docket. I followed Wcass's link to the foams on McMasterCarr, and decided to order Soft and Extra Soft in thicknesses of 1/16, 1/8, and 3/16 of an inch. And now that I wrote that out, I realized it was completely unnecessary for me to order in 3/16" because that will be much too thick.

On another note, who wants some 3/16" foam?

quantalume

22 May 2014, 08:23

How did you manage to get the plates back together? I was thinking of leaving just the bottom tabs intact, using bolts in the middle and some sort of clips at the top.

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vivalarevolución
formerly prdlm2009

22 May 2014, 13:32

quantalume wrote:How did you manage to get the plates back together? I was thinking of leaving just the bottom tabs intact, using bolts in the middle and some sort of clips at the top.
For an F122, Clamps to keep the plates together and a large sliding C-clamp to force long ends of the plates together and slide everything into the clips. Fohat.digs guide has some good pictures. It is not easy.

For a kishsaver, I was just able to put it together with my hands.

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Game Theory
Mr. Despair

22 May 2014, 13:56

prdlm2009 wrote: For an F122, Clamps to keep the plates together and a large sliding C-clamp to force long ends of the plates together and slide everything into the clips. Fohat.digs guide has some good pictures. It is not easy.
That's the method I used. (cheap) side clamps to keep the plates together and long clamp to force the plates to match up.

User avatar
Muirium
µ

22 May 2014, 14:37

prdlm2009 wrote:For a kishsaver, I was just able to put it together with my hands.
Same here. The Kishsaver is so easy to work on, it might as well be the training vehicle for larger Model Fs!

I was nervous opening mine, because I've no idea how I'd replace it. But it turned out to be as easy as pie to open and close, fortunately.

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vivalarevolución
formerly prdlm2009

22 May 2014, 16:51

Game Theory wrote:
prdlm2009 wrote: For an F122, Clamps to keep the plates together and a large sliding C-clamp to force long ends of the plates together and slide everything into the clips. Fohat.digs guide has some good pictures. It is not easy.
That's the method I used. (cheap) side clamps to keep the plates together and long clamp to force the plates to match up.
I should mention that I got those side clamps for 99 cents from Lowes. If you are in the United States, they should be easy to get on the cheap from any large hardware chain.

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Muirium
µ

22 May 2014, 16:52

What do they look like? (I rummage through my dad's tools whenever I visit!)

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wcass

22 May 2014, 17:36

I've also used standard office supply binder clips. If you try it, cover the "teeth" with electrical tape so it doesn't scratch your plates.
http://www.officedepot.com/a/products/8 ... -34-Black/

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vivalarevolución
formerly prdlm2009

22 May 2014, 20:13

Muirium wrote:
prdlm2009 wrote:For a kishsaver, I was just able to put it together with my hands.
Same here. The Kishsaver is so easy to work on, it might as well be the training vehicle for larger Model Fs!

I was nervous opening mine, because I've no idea how I'd replace it. But it turned out to be as easy as pie to open and close, fortunately.
The clamps are similar to what Fohat used in the pictures in his thread:

http://geekhack.org/index.php?topic=487 ... msg1122437

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Game Theory
Mr. Despair

23 May 2014, 02:11

prdlm2009 wrote:The clamps are similar to what Fohat used in the pictures in his thread:

http://geekhack.org/index.php?topic=487 ... msg1122437
Same for me.

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Hypersphere

23 May 2014, 15:43

wcass wrote:I've also used standard office supply binder clips. If you try it, cover the "teeth" with electrical tape so it doesn't scratch your plates.
http://www.officedepot.com/a/products/8 ... -34-Black/
Glad to see this! I was thinking of using binder clips, as I already have some on hand and in different sizes. Thanks for the tip about putting electrical tape on the inside gripping edges to avoid scratching the plates.

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Hypersphere

23 May 2014, 20:38

What are your views on doing a "bolt mod" on each of the Model F boards (Kishsaver, XT, AT, 122)? Because the Model F plates are not held together initially by rivets or bolts, a bolt mod would not be necessary as it is with Model M boards, but I have seen at least one post of an F-122 restoration that advocated installing around 8 bolts.

In addition, would it be possible to modify an AT in some way to tighten up the case? The case on an XT is really solid, but the AT has some flex and does not feel as solidly pulled together. I don't have my Model F-122 yet for comparison.

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vivalarevolución
formerly prdlm2009

24 May 2014, 00:54

Just got a shipment of the foam mate from McMaster Carr. They are more firm than I expected but they should work. I am a little worried the 1/16" is too thin, but the 1/8". They did not have a 3/32" in a reasonable price and functionality, but I would have loved to try that.

Everything that I bought is non-absorbent closed cell, so I wonder if the open cel would feel differently. I just thought it would be prudent to get something that would not be conducive to absorbing liquids.

Paralel

24 May 2014, 01:19

prdlm2009 wrote:Just got a shipment of the foam mate from McMaster Carr. They are more firm than I expected but they should work. I am a little worried the 1/16" is too thin, but the 1/8". They did not have a 3/32" in a reasonable price and functionality, but I would have loved to try that.

Everything that I bought is non-absorbent closed cell, so I wonder if the open cel would feel differently. I just thought it would be prudent to get something that would not be conducive to absorbing liquids.
Having worked with various foams, I can say, with little doubt, the open cell stuff would have been much less firm and rigid, assuming all other characteristics other than cell openness are identical.

User avatar
fohat
Elder Messenger

24 May 2014, 02:31

rjrich wrote:What are your views on doing a "bolt mod" on each of the Model F boards (Kishsaver, XT, AT, 122)?

I have seen at least one post of an F-122 restoration that advocated installing around 8 bolts.
My original guide showed a bolt mod for the F-122 with bolts replacing the tabs. I have concluded that this is a bad idea and the the tabs are required for proper alignment, etc.

I have found, however, that a couple of bolts at the inside of the curvature of the plates will work wonders.

For my last several operations, I have used 1 bolt between upper 5 and upper F5, and 1 between Enter and up arrow.

*BE SURE TO LOOK AT THE PCB IN BETWEEN AND DO NOT DRILL THROUGH ANY TRACES!*

I used 1/2" long 4-40 machine screws and nuts with washers tightened them down hard.

You may find that this brings stubborn keys back to life. Remember that with the capacitive sensing, alignment and spacing is precise and critical.

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Hypersphere

24 May 2014, 15:45

fohat wrote:
rjrich wrote:What are your views on doing a "bolt mod" on each of the Model F boards (Kishsaver, XT, AT, 122)?

I have seen at least one post of an F-122 restoration that advocated installing around 8 bolts.
My original guide showed a bolt mod for the F-122 with bolts replacing the tabs. I have concluded that this is a bad idea and the the tabs are required for proper alignment, etc.

I have found, however, that a couple of bolts at the inside of the curvature of the plates will work wonders.

For my last several operations, I have used 1 bolt between upper 5 and upper F5, and 1 between Enter and up arrow.

*BE SURE TO LOOK AT THE PCB IN BETWEEN AND DO NOT DRILL THROUGH ANY TRACES!*

I used 1/2" long 4-40 machine screws and nuts with washers tightened them down hard.

You may find that this brings stubborn keys back to life. Remember that with the capacitive sensing, alignment and spacing is precise and critical.
Thanks for the tip on bolt-modding the F-122. Did you use steel washers or rubber washers?

User avatar
Muirium
µ

25 May 2014, 01:51

Bolt modding a Model F seems like a lot of effort, and risk, for little reward. You probably don't want to do it unless there's something very wrong with the board's feel. It's not an access and maintenance procedure, the way it is on Model Ms.

User avatar
wcass

25 May 2014, 02:45

Something you might try ... remember those binder clips I brought up a while ago? Look for the 3/4" wide, 3/8" thick ones. Put an inch long strip of electrical tape into the "mouth" of the clip so that it goes as deep into the corners as you can get it. The tape should be just inside the clip on all sides. Clip this over front and back plates; it should be a tight fit, so why not leave it on? The silver metal "handles" can be removed by squeezing each handle perpendicular to how you would normally squeeze the two together. You can use this to supplement the sliding notches or in place of a malfunctioning one.

My XTant project will be using just two bolts (under the "home row") and 8 or 10 of these clips.
clip-top.JPG
clip-top.JPG (231.22 KiB) Viewed 3321 times
clip-bottom.JPG
clip-bottom.JPG (221.67 KiB) Viewed 3321 times

quantalume

25 May 2014, 03:33

I had a similar idea. For the F-122, I was going to leave the original tabs on the bottom, cut the middle tabs off and put bolts under the function rows, and cut the tabs off the top and use clips like that, maybe two above the numeric pad, 3-4 above the function row and one above the LHS cluster. That way, you could slide the bottom in place, then pivot and bolt/clip the rest. It should make reassembly a lot easier and yet still retain the alignment features of the bottom tabs.

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Hypersphere

25 May 2014, 15:58

quantalume wrote:I had a similar idea. For the F-122, I was going to leave the original tabs on the bottom, cut the middle tabs off and put bolts under the function rows, and cut the tabs off the top and use clips like that, maybe two above the numeric pad, 3-4 above the function row and one above the LHS cluster. That way, you could slide the bottom in place, then pivot and bolt/clip the rest. It should make reassembly a lot easier and yet still retain the alignment features of the bottom tabs.
Interesting. I had thought of doing something similar with clips -- leaving some of them in place. However, I have seen these clips break along the back edge after some time. Bolts would be more dependable; you just need to be careful drilling the holes not to disrupt the PCB.

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fohat
Elder Messenger

26 May 2014, 18:21

Guys, I have done it all these ways, and I *now* recommend leaving all the tabs in place. It may cost you a few (tens of) minutes wrestling the beast back together, but it will be worth it. I now consider my original "bolt-mod" to be wrongful.

2 bolts - 1 between 5% and upper F5, and 1 between Enter and up arrow, will pull that inner curvature where you need it to be. Remember to guard those traces in the PCB layer!

http://www.michaels.com/creatology-foam ... _-Foam_-b3

Creatology Foam Sheet 12"x18" many colors

quantalume

26 May 2014, 19:12

And there you have it. No use experimenting with novel techniques on these rare boards when the experts have been there, done that.

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Hypersphere

26 May 2014, 19:35

quantalume wrote:And there you have it. No use experimenting with novel techniques on these rare boards when the experts have been there, done that.
This could often be true. However, if people had left well enough alone, we would still be flying around in prop-driven biplanes instead of jets. ;)

User avatar
Muirium
µ

26 May 2014, 20:25

And given how old jets are, we'd be in hypersonic rocket cars if we'd actually kept up…

Strange how so much rapid progress used to be in transportation in the 19th and first half of the 20th century. Then it all slowed right down. Did all the great minds really up and move to semiconductors?

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Hypersphere

26 May 2014, 20:44

Muirium wrote:And given how old jets are, we'd be in hypersonic rocket cars if we'd actually kept up…

Strange how so much rapid progress used to be in transportation in the 19th and first half of the 20th century. Then it all slowed right down. Did all the great minds really up and move to semiconductors?
Too true! During the race to the moon, unfortunately fueled by competition with the Russians rather than by more noble motives, there was excitement and momentum. Had this continued, some of us might be living in colonies on Mars or Europa, but things have stagnated. Today's students are adept at social media, but relatively few seem attracted to hard sciences. It seems that we humans require motivation from external threatening forces.

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