IBM Model F foam sheet replacement

[fohat.digs]

People have repeatedly asked me about the foam sheet that I used to replace my mats.

This is a cheap simple product that I have bought at "Michael's Art Supply" but I have never found a link on there website, although it is always on hand in the stores.

It turns up in a sale flyer I got today, for a "one-day only" sale, but this is what I am talking about. If I felt like driving today, I would probably nab a few.

I used the Creatology Foam Sheet 12"x18" and had to splice on a small rectangle for the left function keys with masking tape or electrical tape.

http://www.michaels.com/creatology-foam-for-kids/daily-deal-foam?cm_mmc=EMAIL-_-0526OnlineSpec-_-Foam_-b3

[Hypersphere]

Thanks for posting this. Which of the products shown in the Michael's links do you use?

[0100010]

OST...

[fohat.digs]

OST...

What does OST mean?

[jwaz]

Nice, I need to go pick a bunch of this stuff up. 

[vivalarevolución]

I have also found that these foam mats from McMaster Carr to be useful, although everything that I purchased was closed cell foam, which is firmer than the stock foam on a Model F.  Open cell foam might be spongier and softer, but I have not purchased any yet.  Also, these foams can be purchased in lengths that are long enough to use as one piece for the Model F 122.  The art foam is only 18 inches long, which requires the refurbisher to use a second small piece for part of the foam mat of the Model F 122.

 mcmaster_foam.docx (115.82 kB - downloaded 236 times.)

[fohat.digs]

I have also found that these foam mats from McMaster Carr to be useful, although everything that I purchased was closed cell foam, which is firmer than the stock foam on a Model F.  Open cell foam might be spongier and softer, but I have not purchased any yet.  Also, these foams can be purchased in lengths that are long enough to use as one piece for the Model F 122.  The art foam is only 18 inches long, which requires the refurbisher to use a second small piece for part of the foam mat of the Model F 122.

(Attachment Link)

I got a piece from wcass last year that was probably the soft 1/16" and I thought that it was far too soft and/or thin.

In comparison, the art foam, also at about 1/16" is vastly firmer.

1/8" in a medium might be about right, if it will compress and move without wrinkling.

[vivalarevolución]

I have also found that these foam mats from McMaster Carr to be useful, although everything that I purchased was closed cell foam, which is firmer than the stock foam on a Model F.  Open cell foam might be spongier and softer, but I have not purchased any yet.  Also, these foams can be purchased in lengths that are long enough to use as one piece for the Model F 122.  The art foam is only 18 inches long, which requires the refurbisher to use a second small piece for part of the foam mat of the Model F 122.

(Attachment Link)

I got a piece from wcass last year that was probably the soft 1/16" and I thought that it was far too soft and/or thin.

In comparison, the art foam, also at about 1/16" is vastly firmer.

1/8" in a medium might be about right, if it will compress and move without wrinkling.

Yea, that it my assessment of the foams as well.  I should have clarified.  1/8" might be too thick.

In comparison the stock foam mat, I found even the Extra Soft from McMaster to be firmer than the stock foam mat.  However, the art foam is firmer than the Soft or Extra Soft from McMaster.

I might get some soft cell, absorbent foam in 1/8 thickness, and try that out.  In that variety, these seem to be the most affordable offerings from McMaster:

http://www.mcmaster.com/#86225k11/=s5e514

http://www.mcmaster.com/#8601k41/=s5e54p

http://www.mcmaster.com/#87035k41/=s5e5be

I might buy all three and try them out.

[0100010]

OST...

What does OST mean?

Old school tag.  Carryover behavior from other message boards.

[Hypersphere]

I found art foam in approximately 3/32 or about 2 mm thickness in 36 x 60 inch rolls for $9.95:
https://www.craftsuppliesforless.com/kidscraftsupplies_foamsheets.html

In addition, CS Hyde has all sorts of silicone sheets, including silicone foam and sponge in various grades and thicknesses, including 3/32 inch:
http://catalog.cshyde.com/category/silicone-products

The silicone products are expensive, but they offer many advantages, including long-term compatibility with metal surfaces.

[fohat.digs]

Go for it, guys!

I "did my thing" on my own without the benefit of help or high-tech wizardry. I imagined what I needed to replace the horrible remnants of the foam pad I found in my F-122 and bought something that was local and cheap. Colorful and interesting was a bonus.

I had done an AT and a couple of XTs previously, and the mats were acceptable, so I did not worry about it until I got a really bad one.

Personally, I really like the art mats and think that the extra thickness and density helps to contain the excessive pinginess of the Model F, and gives a very solid feel to the board which I like. The downside is that it makes the assembly very hard to slide fit back together.

If you can accomplish this, I think that the result is great. But considerably thicker, softer mats may well be much easier to work with. I am a big strong guy with big strong hands and I am not afraid to use tools like serious clamps and hammers, but if you are intimidated by wrestling with these components, then a more pliable and forgiving mat is in order.

[vivalarevolución]

I am a big strong guy with big strong hands and I am not afraid to use tools like serious clamps and hammers, but if you are intimidated by wrestling with these components, then a more pliable and forgiving mat is in order.

This sounds like something you would put in a Craigslist Personals ad.

[vivalarevolución]

after trying out about a half-dozen different foams from McMaster Carr, I found that the original recommendation from wcass, the closed cell neoprene foam, is the best combination of compressibility, durability, and affordability offered by McMaster Carr.  Many of the softer open cell foams are closer in texture and softness to the original Model F foam, but they seem to lack in durability and I had trouble pounding holes into them with the leather hole punch!

http://www.mcmaster.com/#8647k102/=s9x8kf

I decided to use 1/8" thickness because I did not like all the open space left by 1/16", but I am having some difficulty getting it all back together.  That might be operator error more than anything, and I really do not like the swivel head on my clamp.  A swivel head does not work well forcing together such thin pieces of metal.

You probably could find better foams for this application, but I was not willing to pay more than a few dollars for each type of foam.

Also, if anybody is interested, I have tons of foam that you can have if you want it.

[fohat.digs]

I really do not like the swivel head on my clamp.  A swivel head does not work well forcing together such thin pieces of metal.

This is the biggest sore spot for me, too. Each time I do it I start thinking about how to get around it.

There is a place where the plate makes a 90 degree bend into a small lip. That is the only place you have a chance. I still assume that it will take me 3-10 tries to get it hold long enough to make it slide the couple of millimeters required for purchase.

If I had a welding rig, a very small length of pipe (for the swivel head to seat into) welded to a small angle or C channel would be great.

[Hypersphere]

after trying out about a half-dozen different foams from McMaster Carr, I found that the original recommendation from wcass, the closed cell neoprene foam, is the best combination of compressibility, durability, and affordability offered by McMaster Carr.  Many of the softer open cell foams are closer in texture and softness to the original Model F foam, but they seem to lack in durability and I had trouble pounding holes into them with the leather hole punch!

http://www.mcmaster.com/#8647k102/=s9x8kf

I decided to use 1/8" thickness because I did not like all the open space left by 1/16", but I am having some difficulty getting it all back together.  That might be operator error more than anything, and I really do not like the swivel head on my clamp.  A swivel head does not work well forcing together such thin pieces of metal.

You probably could find better foams for this application, but I was not willing to pay more than a few dollars for each type of foam.

Also, if anybody is interested, I have tons of foam that you can have if you want it.

For the neoprene foam, it looks like 1/16" is too thin and 1/8" is too thick. Unfortunately, it appears that McMaster-Carr does not have 3/32" neoprene foam. CS Hyde has 3/32" silicone foam and silicone sponge, but these products are much more expensive than neoprene foam.

[fohat.digs]

For the neoprene foam, it looks like 1/16" is too thin and 1/8" is too thick.

I doubt that 1/8" is too thick, as long as it will crush. You want the barrels to seat into something.

And, in my opinion, the extra padding makes the feel more solid.

[Hypersphere]

For the neoprene foam, it looks like 1/16" is too thin and 1/8" is too thick.

I doubt that 1/8" is too thick, as long as it will crush. You want the barrels to seat into something.

And, in my opinion, the extra padding makes the feel more solid.

OK -- that is useful to know! Thanks.

[vivalarevolución]

The 1/8" is a little thick.  I will see if it is too tight once I get it all together, which is an undetermined date because I am having such a hard time getting it all together this time around.

[agodinhost]

Thanks for the links.

I am a big strong guy with big strong hands and I am not afraid to use tools like serious clamps and hammers, but if you are intimidated by wrestling with these components, then a more pliable and forgiving mat is in order.

This sounds like something you would put in a Craigslist Personals ad.

More to a sex ad ...
 

The silicone products are expensive, but they offer many advantages, including long-term compatibility with metal surfaces.

+1

[Hypersphere]

Today I got some of the 12 x 18 inch "art foam" sheets ("Creatology" brand) in white and yellow from Michael's. I noticed that the label said "acid free", which is good for something that will be in contact with metals. Using a micrometer, I measured the thickness of several sheets; they are all close to 2.03 mm or 0.080 inches in thickness. For your convenience, this thickness is in between 1/16 (0.0625) inches and 3/32 (0.09375) inches. As fohat.digs has pointed out, this art foam material is inexpensive, nice to work with, and in the light colors it can be legibly marked with a pen or paint to indicate where holes are to be punched.

I am still waiting to get some samples of silicone foam and silicone sponge from C.S. Hyde for comparison. They have a good selection of thicknesses, including 1/16, 3/32, and 1/8 inch.

[vivalarevolución]

As for the clamp issue, I found some non-swivel bar clamps from Grainger that would be useful for this application:

http://www.grainger.com/product/WESTWARD-I-Bar-Clamp-Regular-Duty-2-10D588?s_pp=false

http://www.grainger.com/product/WILTON-I-Bar-Clamp-5A325?s_pp=false

Unfortunately, they are a little pricier than the typical two-foot bar clamp.

But, as always, Harbor Freights saves the day with a cheaper option that probably will only last you for a few applications:

http://www.harborfreight.com/aluminum-bar-clamp-60541.html

[vivalarevolución]

Great news!  I sped off to Harbor Freight after work, and picked up that bar clamp I linked before.  Because it did not have a swivel head, it worked on the first try.  What a breeze!

However, I would recommend the 36" over the 24" because the 24" barely expands enough to fit over a Model F 122.

[fohat.digs]

I sped off to Harbor Freight after work, and picked up that bar clamp I linked before.  Because it did not have a swivel head, it worked on the first dry.  What a breeze!

Thank you ever so much for this tip!

[agodinhost]

There is the EVA sheet too - cheaper than silicone and softer than black rubber.
You can see EVA in those kids puzzled colored carpets.

Right now I'm doing some experimentation and I'm quite happy with it.

[vivalarevolución]

Hey guys.  I did not know it was possible, but the custom foam sheet that I added to my Model F 122 seems to have made the keyboard feel even more solid.  Consider how solid these feel without a foam sheet mod, I find this ridiculous.

[fohat.digs]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

[Hypersphere]

CS Hyde sent only 3 samples of their silicone foam/sponge sheets, making it difficult to make a selection. McMaster-Carr has a sampler pack that they will send for a fee. In any event, I went ahead and ordered 1/8 (0.125) inch foam and sponge sheets from CS Hyde, because they had more detailed specs and more sizes available. I also ordered neoprene foam (0.125 inch) from McMaster-Carr. It will be some time before I can try out the various products, but I will post my findings.

[dorkvader]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

Sadly my 2mm art foam mat is preventing me from reassembling the F. In this case, it's not worth. Perhaps on a beam spring it could work.

Maybe I can find some 1.5mm or less.

[vivalarevolución]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

Sadly my 2mm art foam mat is preventing me from reassembling the F. In this case, it's not worth. Perhaps on a beam spring it could work.

Maybe I can find some 1.5mm or less.

Could you provide more details on why that art foam is not working for you?

[Hypersphere]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

Sadly my 2mm art foam mat is preventing me from reassembling the F. In this case, it's not worth. Perhaps on a beam spring it could work.

Maybe I can find some 1.5mm or less.

Which model F? Are you using spring clamps to hold the plates together and a bar clamp to slide them into position?

Some people report that the foam needs to be highly compressible. Perhaps your art foam is too rigid?

[fohat.digs]

Some people report that the foam needs to be highly compressible. Perhaps your art foam is too rigid?

I have now done about 10-12 of these. 2-3 were noticeably more difficult than the others, and 2-3 were much easier.

There are factors at play here, but the most important is probably the radius of curvature of each of the 3 plates that slide together. Since these beasts are all 3 decades old, cycles of heating and cooling, humidity, stress and pressure, all may have made minutes changes to the exact tension/compression relationship between the plates sandwiched together. And the longer they stay apart, the more likely the outer layers are to try to straighten themselves (the inner, most curved plate, is also the thickest).

The art foam that I bought at Michael's is decidedly thicker and stiffer than the original, and there is no doubt that it will make the re-assembly considerably more difficult (hence the need for clamps). But the up-side is that it really makes the sound and feel more solid, to me, at least.

[vivalarevolución]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

Sadly my 2mm art foam mat is preventing me from reassembling the F. In this case, it's not worth. Perhaps on a beam spring it could work.

Maybe I can find some 1.5mm or less.

Which model F? Are you using spring clamps to hold the plates together and a bar clamp to slide them into position?

Some people report that the foam needs to be highly compressible. Perhaps your art foam is too rigid?

I don't think the foam needs to be highly compressible.  But it may make it a little easier to put everything together.  The trade-off for a highly compressible foam might be durability.

[jevvix]

made the keyboard feel even more solid.

Precisely why I always advocate for the nice firm art foam, even considering the additional heartache.

Sadly my 2mm art foam mat is preventing me from reassembling the F. In this case, it's not worth. Perhaps on a beam spring it could work.

Maybe I can find some 1.5mm or less.

I'm having the same problem. Using 6-10 clamps, two people and a bar clamp on the XT, it will not close with the art foam. In fact, it's not even close. Considering the original foam in it when I disassembled it was paper thin and it still felt solid, I think I'm going to opt for something much thinner like 1mm or that is not as firm.

All this for a stabilized space bar. Really regretting my decision to take it apart at this point.

[fohat.digs]

Really regretting my decision to take it apart at this point.

Very sorry to hear that. I did at least 4 XTs using only hand pressure, that was way back before I got into the big F-122s and started needing clamps. Do you recognize that you just need to slide the plates far enough together to minimally engage the tabs and slots? Once they are engaged, you can stand it on end and tap it with a hammer the rest of the way. When you are comfortable that the pivot plates will not "jump tracks" you can bang it around all you want.

The art foam from Michael's is nominal 1/16" or approx 1.5mm. I would certainly not recommend anything thicker unless it was very compressible, and that would not afford as much dampening.

[dorkvader]

Could you provide more details on why that art foam is not working for you?

It's too thick and I can't get the model F closed. I suspect that the foam is indeed to rigid. This is on a 122-key model F. I do have a 24" clamp I am using to try and close it.

Note that the radius of curvature is very different, making it hard to bend the center into place for assembly. I hope to get some different material or try O-rings at some point in the future.

[fohat.digs]

Note that the radius of curvature is very different, making it hard to bend the center into place for assembly.

I don't know how strong your hands and fingers are, but the inside of the curve needs as much help as you can give it. I always try to press the front into the back as hard as I can to get it started. A second person might help (I have never had that luxury) but a second pair of arms would be even better. I conceptualize it as my hands doing the work and the clamps assisting, rather than vice-versa.

Of course, this was the problem that started me on the original "Harry's Bolt-Mod" where I cut off the tabs and used bolts instead. The reason that I abandoned and deprecated that technique was that I realized how important the alignment was in both planes, and that keeping the tabs was the only realistic way to ensure the proper fit.

[jevvix]

Really regretting my decision to take it apart at this point.

Very sorry to hear that. I did at least 4 XTs using only hand pressure, that was way back before I got into the big F-122s and started needing clamps. Do you recognize that you just need to slide the plates far enough together to minimally engage the tabs and slots? Once they are engaged, you can stand it on end and tap it with a hammer the rest of the way. When you are comfortable that the pivot plates will not "jump tracks" you can bang it around all you want.

The art foam from Michael's is nominal 1/16" or approx 1.5mm. I would certainly not recommend anything thicker unless it was very compressible, and that would not afford as much dampening.

Yep and yep. We got it to that point several times after minutes of hammering thinking it was enough because it held together on its end without the clamps... but as soon as we flipped it on to its back and put caps on it would pop apart. We used a small sledge hammer to tap it in to place while vertical but it was not having any of it. Really surprised nothing broke. We attempted it for a few hours without any success. Trust me when I say there is no way it would reassemble. Even then if we did manage to get it together good chance the space bar hammer would have been improperly seated (are there any tricks to this?) and we'd have to take it apart again.

It's really too bad since the neon green art foam from Michael's looks really cool (poor lighting and phone camera aside):



As I mentioned, the old foam mat was so far gone that it felt like electrical tape yet the keyboard seemed solid and typed well. There was absolutely no foam left and it was paper thin. I'm going to try reassembling it without any material and see how it feels. If that doesn't work, I found this on Home Depot's site that I may try: http://www.homedepot.com/p/Pratt-Retail-Specialties-1-16-in-x-12-in-x-50-ft-Dish-Foam-Roll-20020010/202530553 Surely not as durable as the art foam but I there's enough of it for a lifetime of Model F foam replacements.

I guess this is one of those "your mileage may vary (a lot)" modifications.

[fohat.digs]

are there any tricks to this?

First, ensure that all the tabs on the front plate are straight, that is, square and perpendicular to the surface so that they mate properly with the back plate.

Hopefully you did see that one tab is usually bent over (often the one over the numpad, in my experience) to lock everything down. It needs to be straightened up.

It is imperative that the tabs all pass through their slots/holes/notches nicely before you start sliding the plates against each other. I have occasionally tweaked the tabs slightly out of vertical to get them started. Later, you can bend the perimeter ones slightly inward to tighten everything up.

Some are much harder than others, but the XTs I have done are much easier than the others (except for the pesky spacebar).

After the tabs and slots are engaged, a couple of light taps with an ordinary hammer should be all that is required.

[Parak]

Here's the foam that worked extremely well for me, after trying multiple different options - silicone, epdm, different foam grades and thicknesses, and orings (could still work really well, just needs to be 20 or 30a at most). Anyway, the foam:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=251610414297

Soft, yet fairly tear resistant. With it there's very slight play in the barrels on the center row, and none on the other rows. The center row play is so insignificant, that the keycaps wobble more than the actual barrel. YMMV of course depending on what you use it on - this was on a kishsaver for me. Also cheap.

[jevvix]

I tried the XT assembly again one last time and it's still far off with the creatology foam.

Then, I assembled it with no material between the barrels and the front plate. To my surprise, it actually felt really solid except a slight wobble in the center row. The outer rows were great and there was absolutely no movement in the barrels. Apparently my XT has really high/extreme tolerances from the factory or something.

Here's the foam that worked extremely well for me, after trying multiple different options - silicone, epdm, different foam grades and thicknesses, and orings (could still work really well, just needs to be 20 or 30a at most). Anyway, the foam:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=251610414297

Soft, yet fairly tear resistant. With it there's very slight play in the barrels on the center row, and none on the other rows. The center row play is so insignificant, that the keycaps wobble more than the actual barrel. YMMV of course depending on what you use it on - this was on a kishsaver for me. Also cheap.

How is this stuff in terms compressibility? The current art foam I'm using is fairly firm and it's lack of compressibility seems to be what's keeping me from assembling my board. I think for my specific XT's tolerances I need something a bit more softer.

[Parak]

It compresses down to 1/64" as tested via calipers which is what foam should be doing in this application.

[vivalarevolución]

Also, I mentioned all this info earlier in the thread.

Here is the foam that worked best for me.  It also comes in 1/16 thickness.  I found the 1/8 suitable for the F122, but I am not sure about the XT.

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

1/16 is a safer bet, because it is not as tight of a fit and has more play, but still keeps the barrels in place.  The 1/8 thickness fills up the gaps between the metal plates really well.  Ideally, I would like to try a 3/32 of an inch thickness, but that does not seem to be made in nearly as many varieties as 1/16 and 1/8.


Also, I highly recommend this clamp from Harbor Freight, because it does NOT have a swivel head.

http://www.harborfreight.com/Aluminum-Bar-Clamp-60539.html

I struggled with the swivel head clamp for days, and then I went and bought that thing, and it worked on first try.  Amazing how things work when you have the right tools.

[dorkvader]

I think I'm going to mod my swivel clamp to be rigid.

[jevvix]

Here is the foam that worked best for me.  It also comes in 1/16 thickness.  I found the 1/8 suitable for the F122, but I am not sure about the XT.

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

1/16 is a safer bet, because it is not as tight of a fit and has more play, but still keeps the barrels in place. 

Thanks! I saw this earlier in the thread and my 1/16" arrived today. I'm happy to report my XT is back together! The 1/16" of that material works perfectly except the long space bar 'barrel' had to be directly against the metal in order for the two plates to close. It doesn't seem to be a problem though since the space bar 'barrel' is snug with minimal if any wobble without the foam under it.

Also, to get the space bar spring/hammer correctly seated in the XT I used a very small pocket knife to hold it down in place while I placed the backplate/pcb on and then clamped it down with my other hand. Seemed to work a treat since I got it positioned first try.



I believe I've sourced a new left leg that was broken in shipping... and then all that's left is to take the plates apart one more time, remove the corrosion/rust from the plate and give her a respray Should be better than new!

[sleepy916]

Here is the foam that worked best for me.  It also comes in 1/16 thickness.  I found the 1/8 suitable for the F122, but I am not sure about the XT.

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

1/16 is a safer bet, because it is not as tight of a fit and has more play, but still keeps the barrels in place. 

Thanks! I saw this earlier in the thread and my 1/16" arrived today. I'm happy to report my XT is back together! The 1/16" of that material works perfectly except the long space bar 'barrel' had to be directly against the metal in order for the two plates to close. It doesn't seem to be a problem though since the space bar 'barrel' is snug with minimal if any wobble without the foam under it.

Also, to get the space bar spring/hammer correctly seated in the XT I used a very small pocket knife to hold it down in place while I placed the backplate/pcb on and then clamped it down with my other hand. Seemed to work a treat since I got it positioned first try.

Show Image

I believe I've sourced a new left leg that was broken in shipping... and then all that's left is to take the plates apart one more time, remove the corrosion/rust from the plate and give her a respray ;D Should be better than new!

That XT is in really good shape!  ^-^

[Jotokun]

My 122-key Model F has foam from Michaels in it.



It was tough to get closed initially, I found I had to use a pretty good clamp to get it to work.



The style on the bottom was what I initially tried, and I've come to the conclusion that they don't work. It kept slipping off before I could get the plates completely aligned, and then they would pop apart if I tried to do more with it. I had a smaller version of the one on top, and on a whim I tried it on the upper portion of the board with success. It popped back open immediately after the clamp was removed since I couldn't get the main body tight enough to match.

Picked up the larger one pictured so it would fit the main part of the body, and it worked on the first try. It just doesn't slip, and having separate triggers for tightening and loosening it makes it pretty easy to work with. It did require quite a bit of force to squeeze near the end, but otherwise it made getting the plates together look easy. Didn't have to do any cutting or bolt modding either.

[fohat.digs]

This thread contains another interesting discussion on this topic:

http://geekhack.org/index.php?topic=61968.new#new