Replacement Foam Mat for IBM Model F Keyboards?

[Paralel]

I think we will see that "external force", so to speak, come from China in the not too distant future. I think this will spur a second science renaissance in the US just like the cold war did in the middle of the 20th century. Or, at least I can dream...

[Muirium]

It's a fine dream!

The Chinese are determined to land on the Moon, which would be something when NASA can't even launch manned missions into low Earth orbit by itself right now. If anything were to get us to Mars, it would be a wakeup call like that. Just as Sputnik caught America unawares!

The bigger problem with space, though, is profit. We have yet to figure out a way to launch that's cheap enough to justify things like space mining and actual tourism beyond the ISS. The Earth itself was a rich place for the explorers of the last millennium, and funded empires soon enough. Space, meanwhile, has yet to prove itself to us. Unless prestige is at stake, we just don't much care for it.

None of which explains why our earthbound transport is still strikingly similar to how it was in 1960. That one's more of a mystery to me. There's lots of money in aviation, but not much thinking different.

<Looks up at thread title, grins, and thinks "only at Deskthority">

[quantalume]

As a point of reference, I recently came into possession of a pristine XT Model F. This keyboard came from a sparsely-populated region where there would not have been any airborne pollutants like ozone to attack the foam. I just now measured the thickness, and it is 3/32" or 2.4 mm.

[vivalarevolución]

So I used the 1/16 on an inch foam for replacement foam on my Model F 122. I find it too be a little to thin because it leaves a lot of free space between the two plates it is wedged between. With that said, all but three of the keys work properly, and I do not think that malfunctioning of those keys is due to the thin foam mat. The hammers seem to get stuck and they do not have the same freedom of movement as the working keys. There is a delay in the spring and hammer assembly actuating properly. It is hard to explain with only words.

3/32" seems like the proper width for these mats, and open cell might be softer and more similar to the original foam. 1/8" is definitely too wide.

On another note, I have a bunch of 3/16" and 1/8" foam if anybody wants it for anything.

[Hypersphere]

It's a fine dream!

The Chinese are determined to land on the Moon, which would be something when NASA can't even launch manned missions into low Earth orbit by itself right now. If anything were to get us to Mars, it would be a wakeup call like that. Just as Sputnik caught America unawares!

The bigger problem with space, though, is profit. We have yet to figure out a way to launch that's cheap enough to justify things like space mining and actual tourism beyond the ISS. The Earth itself was a rich place for the explorers of the last millennium, and funded empires soon enough. Space, meanwhile, has yet to prove itself to us. Unless prestige is at stake, we just don't much care for it.

None of which explains why our earthbound transport is still strikingly similar to how it was in 1960. That one's more of a mystery to me. There's lots of money in aviation, but not much thinking different.

<Looks up at thread title, grins, and thinks "only at Deskthority">

Colonizing space is actually a matter of survival, but sadly we might not believe this until it is too late.

In other news...back to keyboards!

[Hypersphere]

As a point of reference, I recently came into possession of a pristine XT Model F. This keyboard came from a sparsely-populated region where there would not have been any airborne pollutants like ozone to attack the foam. I just now measured the thickness, and it is 3/32" or 2.4 mm.

I think that the art foam fohat used in his F-122 is about 2 mm thick. In addition, it seems that 3/32 inch is a popular thickness for various types of foam or sponge polymers, including polyurethane by 3M and other polymer sheets available from Grainger and other companies.

[Hypersphere]

Update: This thread has been split. This thread (the original or parent) is focused on replacement foam for IBM Model F keyboards. The new thread is called "Mounting options for Teensy in IBM keyboards" and is focused on electronics and the mechanics of connectors.

Regarding the present topic, I have been in touch with a company called C.S. Hyde (www.cshyde.com) that has products and services related to tapes, films, fabrics, and silicone. They are sending me some samples of silicone foam and silicone sponge. The silicone materials are substantially more expensive than art foam or neoprene foam, but I like the fact that the silicone materials are well defined, highly durable, and chemically inert toward metals. They also have silicone foam and sponge in 3/32-inch thickness. I will let you know what I find after I have had an opportunity to do some comparisons of the various foam replacement materials.

[quantalume]

I will let you know what I find after I have had an opportunity to do some comparisons of the various foam replacement materials.

Great! I'm in the process of restoring a rusty old XT and will hold off reassembly until you report your findings.

[Hypersphere]

Today I got some 12 x 18 inch sheets of "art foam" ("Creatology" brand) from Michaels' Arts and Crafts Store. It is offered in a variety of colors; I got white and yellow. The label said that it is "acid free", which seems like a good idea for something that will be placed in contact with metals inside a keyboard. Using a micrometer, I measured the thickness of several of the sheets; they were all quite close to 2.03 mm (0.080 inches). Note that this thickness lies between 1/16 (0.0625) and 3/32 (0.09375) inches. This is the material that fohat.digs has recommended, noting that it is inexpensive, easy to work with, appropriately compressible, and in the light colors it can be legibly marked to provide guides for punching holes. A single sheet of 12 x 18 inch foam would be sufficient for replacing the foam in an IBM XT or AT keyboard.

I found a similar art foam material ("Darice" brand) supplied in 36 x 60 inch rolls. I think it is available in black or white; I got white to facilitate legible markings. This material is also 2 mm thick, but the label said nothing about "acid free". An advantage of the large size is that a single piece could be cut for use in an F-122 keyboard without needing to tape two pieces together.

I am still waiting to receive samples of silicone foam and silicone sponge from C.S. Hyde. These materials are much more expensive than art foam, but they have many desirable physical/chemical properties and are available in a good assortment of resiliency and thicknesses, including 1/16, 3/32, and 1/8 inches.

[Paralel]

I'll be interested to see what the difference is between a "sponge" and a "foam" of silicone.

[Hypersphere]

I'll be interested to see what the difference is between a "sponge" and a "foam" of silicone.

There are several sources for information on this question. One of them is from the Stockwell Elastomerics site:
http://www.stockwell.com/silicone-sponge.php
"Silicone Sponge or Silicone Foam? What is the Difference?
Silicone sponge, also called closed cell silicone sponge or expanded silicone, is derived from a thin sheet of uncured silicone gum that expands to a controlled thickness while curing in a high temperature press or rotocure operation. Closed cell means that the cells are non-interconnecting, therefore they do not allow water to wick through the sponge. Generally, silicone sponges have superior mechanical properties and are considered to have a complete closed cell structure. Silicone sponge often provides better water sealing in wash-down applications as compared to silicone foam."

"Silicone foam is normally considered to be an open cell, lightweight product that is derived from liquid silicone ingredients that are cast onto a liner and cured in an oven. Higher density silicone foams have been developed, in recent years, that are suitable for water sealing. Low density open cell silicone foams may allow moisture to pass through the cell structure unless the design allows for extensive deflection of the gasket. In contrast, higher density silicone foam products will have a higher proportion of closed cells compared with medium or low density grades. With the proper amount of deflection, it is possible to achieve a good long term weather seal and rain seal with silicone foam."

[vivalarevolución]

Slightly unrelated, but when putting all the parts back together, I found this bar clamp to be the best I have used so far:

http://www.harborfreight.com/aluminum-b ... ?hftref=cj

It does NOT have a swivel head, which makes it extremely useful for putting pressure on such thin metal edges.

[quantalume]

Good find, prdlm! I'm always looking for an excuse to go to Harbor Freight and some rationalization for buying yet another tool. I have the ratcheting kind, but I can see that this one would be better. Looks like it is barely big enough for the F-122!

[Hypersphere]

Good find, prdlm! I'm always looking for an excuse to go to Harbor Freight and some rationalization for buying yet another tool. I have the ratcheting kind, but I can see that this one would be better. Looks like it is barely big enough for the F-122!

They are available in larger sizes if needed.

[xwhatsit]

I wonder how applicable this would be to the beamsprings. I now recall why my 5251 is very rattly (and hence why I prefer my 3727); I believe I pulled the foam out of it completely at one point and chucked it out, as it was beyond repair. This was some years ago and I had forgotten I'd done this.

The 5251 still functions fine and all of the keys have always registered with the controller; the switching action doesn't seem to be quite so sensitive to foam quality and positioning as the Model F appears to be. However the rattle and amount of play visible in the keycaps themselves is definitely unpleasant.

The beamsprings don't have the curved backplate (the keys themselves provide the curve through variable profile keys, a much inferior solution to the Model F and M system), so this may make things slightly easier as there should be less variability in the spacing between top and bottom. There are also much more connection points between the two plates, with screws all the way around.

I'll have to give this a shot when I can find some time.

[vivalarevolución]

Good find, prdlm! I'm always looking for an excuse to go to Harbor Freight and some rationalization for buying yet another tool. I have the ratcheting kind, but I can see that this one would be better. Looks like it is barely big enough for the F-122!

They are available in larger sizes if needed.

Yea, sorry, I would recommend the 3 feet length because the 2 feet length barely fit over the Model F 122 frame.

[Hypersphere]

Thanks for the tip on the aluminum bar clamp. I've ordered the 3-ft model.

I received some silicone sheet samples from CS Hyde. Unfortunately, they sent only 3 samples. One was a material that was not on my wish list and another was below my thickness range. Fortunately, they did send one sample of silicone foam (open cell) and one of closed cell silicone sponge. The closed cell sponge seems a bit too firm, but the open cell foam might be too soft. However, they also make a closed-cell foam. I will probably go ahead and order a couple of sheets of different materials based on my best guess and try them out in an XT. Watch this space for further updates....

[vivalarevolución]

I just wanted to add that the 1/8" foam pad really seems to have added more solidness to my Model F 122. I did not think it was possible to make a Model F more solid, but I guess it is. It also took a lot of work, but I am finally relieved to be done with this Model F mod. It was worth all the pain.

[quantalume]

Is that the same F-122 that you posted before and after photos of on GH? Phenomenal job!

[Hypersphere]

I just wanted to add that the 1/8" foam pad really seems to have added more solidness to my Model F 122. I did not think it was possible to make a Model F more solid, but I guess it is. It also took a lot of work, but I am finally relieved to be done with this Model F mod. It was worth all the pain.

Did you use the soft neoprene foam in 1/8-inch thickness?

The choices of foams and sponges of various kinds are quite varied, and I have seen people report that 1/8-inch is too thick, but perhaps they were using a relatively non-compressible material. At the moment, I have on hand 1/8-inch (0.125 inch) art foam and 2 mm (0.079 inch) art foam.

I would like to try silicone, but I am not sure which variety and thickness to order. Silicone materials are expensive and so mistakes will be costly. The choices of silicone materials include open and closed cell foam, closed cell sponge, and low compression set closed cell sponge. There might also be solid silicone sheets that could work, and these come in more varieties than the foams and sponges. Several thicknesses of each foam or sponge material are available in 1/32-inch increments between 1/32-inch and 1/8-inch (or in larger increments up through 5/8-inch). Sheet sizes are 12 x 12 or 36 x 36 inches.

[vivalarevolución]

Yea, I went with the soft neoprene foam at 1/8". It did seem too thick, but once I got the right bar clamp, things went very smooth. I definitely recommend a softer material with some compressibility.

[Hypersphere]

Yea, I went with the soft neoprene foam at 1/8". It did seem too thick, but once I got the right bar clamp, things went very smooth. I definitely recommend a softer material with some compressibility.

This agrees with an earlier measurement I did on the thickness of the original foam in an XT; it was 1/8 inch (0.125 inch) at the edges. Just now I used a micrometer to measure the inside distance between the plates in an XT; it measures 0.15 inch. Therefore, there ought to be plenty of room for 1/8 (0.125) inch foam as long as it is sufficiently compressible.

This is helpful. I think I will get some of the more compressible silicone foam in 1/8-inch thickness and give it a try.

[Hypersphere]

Yea, I went with the soft neoprene foam at 1/8". It did seem too thick, but once I got the right bar clamp, things went very smooth. I definitely recommend a softer material with some compressibility.

More questions for you. I am looking at the neoprene foam offerings from McMaster-Carr. They have the following types in 1/8" thickness:

Weather-resistant neoprene foam, extra soft or soft (smooth skin on top and bottom)

Weather-resistant neoprene/EPDM/SBR foam, extra soft, soft, or firm (no skin)

Oil-resistant neoprene/vinyl/Buna-N foam, extra soft, soft, or firm (no skin)

Which of these 8 varieties did you use?

In addition, the color of all these products is black. How did you mark the foam to indicate where to punch holes for the spring barrels? Did you print a template on paper and tape this to the foam?

Thanks again.

[vivalarevolución]

The final product I used was this:

http://www.mcmaster.com/#8647k21/=sc1m7g

But I also tried some of those other foams. Are you in the United States? I can ship you some of my left over foam, if you would like to try it out. Send me a PM if you want to discuss the details.

[wcass]

Check out my post from May 19. Whatever thickness you choose, you will want the softest, squishiest neoprene they have. I'm guessing that a skin might add a little firmness, so i go for extra soft, no skin. If you don't expect your foam to be exposed to weather or oil then don't pay extra for it.

Is this for a 122? If so, i'll make a template thay you can print soon. I have been busy with Kishsaver and XTant, but my 122 should get some attention too. So many fun Model F projects to work on.

[Hypersphere]

The final product I used was this:

http://www.mcmaster.com/#8647k21/=sc1m7g

But I also tried some of those other foams. Are you in the United States? I can ship you some of my left over foam, if you would like to try it out. Send me a PM if you want to discuss the details.

Thanks once more. If you have already gotten good results with the foam you have referenced above, I think I will order that one. It is certainly much less expensive than any of the silicone materials. Perhaps if I wanted the foam to last for several decades I would use silicone; even so, I am still tempted to try it. Thanks, though, for your offer of some extra foam; I will certainly keep this in mind and send you a PM if I decide to try out what you have left over.

Did you tape a paper template to the foam to punch the barrel holes?

[Hypersphere]

Check out my post from May 19. Whatever thickness you choose, you will want the softest, squishiest neoprene they have. I'm guessing that a skin might add a little firmness, so i go for extra soft, no skin. If you don't expect your foam to be exposed to weather or oil then don't pay extra for it.

Is this for a 122? If so, i'll make a template thay you can print soon. I have been busy with Kishsaver and XTant, but my 122 should get some attention too. So many fun Model F projects to work on.

I am fortunate enough to have several model F keyboards: AT, XT, and F-122 (as well as some M-122s), so templates for all these would be useful, thanks!

Hoping to get a Kishsaver someday!

[vivalarevolución]

I wonder if the different versions of the Model F might work best with different thicknesses. The eyeball test makes me think the stock foam on Kishsaver is a little thinner than the stock foam on a F122, but I could be wrong. I would need to take a closer look.

To punch the barrel holes, I used fohat.digs method of spray painting the foam while it was attached to the metal plate with binder clips, and then punch holes in the foam with a leather hole punch.

If wcass does create a template for people to use, that would be incredibly useful.

[Hypersphere]

I wonder if the different versions of the Model F might work best with different thicknesses. The eyeball test makes me think the stock foam on Kishsaver is a little thinner than the stock foam on a F122, but I could be wrong. I would need to take a closer look.

To punch the barrel holes, I used fohat.digs method of spray painting the foam while it was attached to the metal plate with binder clips, and then punch holes in the foam with a leather hole punch.

If wcass does create a template for people to use, that would be incredibly useful.

Thanks. Yes, although I was going to paint the plate black, I suppose a light color could be used initially to mark the places for punching holes in the black foam.

Regarding foam thickness, it seems quite plausible that the stock thickness could be different for different models of Model F keyboards, e.g., Kishsaver, XT, AT, and F-122. So far, I have been using an XT for my measurements, because this is the only one I have dismantled. My AT and F-122 are waiting on the bench until I get some experience, starting with an XT.

The best thickness to use for a given model of keyboard could also vary depending on the kind of foam used, e.g., open cell, closed cell, extra soft /soft / firm, silicone foam, silicone sponge, silicone low compression set, neoprene, art foam, foam board, etc.

All things considered, it appears that if you are using art foam, the thickness is about 2 mm or 0.079 inch. If you are using extra soft neoprene foam, the ideal thickness is about 1/8 (0.125) inch. If you are using one of the denser foam materials, then 3/32 (0.094) inch would be appropriate.

[Parak]

As an experiment and partially dfj's suggestion, I tried o rings. Namely, these two:

http://www.amazon.com/gp/product/B000FMWM1I/
http://www.amazon.com/gp/product/B000FN0Y0S/

So, they work. Well, sort of. Using just the first rings, the middle three rows were a bit loose. Using the thicker ones for the middle three rows was a slight improvement in that row 2 got stiffer, row 4 got stiffer, but home row is still a bit too wobbly. Basically what seems to happen is that usage of thicker yet equally stiff material in rows closer to the center will actually raise the top plate, so that the middle row becomes loose. Attempting to increase the thickness of the padding on the home row will just make the other rows worse by raising the plate yet again. At this point my home row keycaps almost touch the plate on bottoming out. Basically, bolt mod would be desirable.

Closing the board with these definitely requires clamps, as they are 75 durometer and do not compress much - in fact it took so much force, that I was starting to get a bit worried as to just how much compression the barrels can take. Turns out, quite a bit. As a benefit to that, aside from the aforementioned home row, is that most every barrel is immovable.

So, cheap, easy to apply, no need for hole punching, but still a bit off from what I'd consider ideal. Perhaps if one could find o rings of lesser durometer at equivalent prices, and decrease durometer in steps towards the home row..

IMG_20140615_184344