Author Topic: Model F 122 Terminal Mod Planning  (Read 3761 times)

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Offline LETE

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Model F 122 Terminal Mod Planning
« on: Mon, 17 October 2011, 14:09:12 »
This is just a place to discuss and plan mods for the Model F 122. If all goes well, some tutorials should stem from this thread.

Projects on the table -

Deteriorated mat replacement (pictures to come, maybe)

F 122 Bolt mod

Offline LETE

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Model F 122 Terminal Mod Planning
« Reply #1 on: Mon, 17 October 2011, 14:21:08 »
Quote from: fohat.digs;431298
So, my amateurish trial and error fumblings continue. I post this stuff, not in a narcissistic way, but to contribute to the greater knowledge, since I have found many answers I needed in ground previously plowed by others. If I should stop, tell me.

I have disassembled 2 Model F 122-key terminals today, 1 from 1984 and 1 from 1985. Below are pictures of the circuit board/metal backplate assemblies, which I do not wish to take apart. They are surprisingly different. The 1984 (August) model is the one that looks all green, as if there is a much thicker layer of fiberglass over the printed contacts. It was in much better condition, and the metal back plate is quite shiny.

The 1985 (January), which is much like the 1985 (June) that I re-habbed and have been discussing for the past month, has the coppery-looking contacts.

My question is which of these boards should I use for my next project? I like the idea of the stronger coating over the circuit, since I have seen a Model F board (an XT 83-key) in which the copper looked like it was more than half eroded (or otherwise erased) away.

The 1984 looks very clean and nice otherwise, and unless there is a compelling reason for the actuation to be harder, such as the electrons have to work harder to get through the extra thickness of fiberglass, then I will use this one.


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I am an Industrial Designer, not an Electrical Engineer, so my intuition is not so deep in this realm. All else being equal, I will chose physical strength, but not at the expense of free flow of energy. Many of you must understand the subtleties and/or minutiae of this process better than I, but you know, miniscule differences matter to me.

Lastly, the rubber mats were in "bad" condition. I was spoiled because the June 1985 in my previous project had a very nice mat, not only was the rubbery surface quite nice, but the foam side was also mostly intact, shedding some 10%-20% but hanging together pretty well.

The mat of the 1985 was terrible, the foam was completely gone, transformed into a very ugly and hard-to-clean rubbery grit, and the thin remainder tore in more than a couple of places. It might possibly be almost "useable" but probably not.

The 1984 was considerably better, although still pathetic, in that the foam was pretty well gone, but the rubbery side was intact and workable. I can probably make it function properly, with some careful jiggling. I am careful and pretty good at making marginal situations viable.

Am I correct in assuming that it would be insanely optimistic of me to imagine that there is any way of getting replacement rubber mats, besides buying Model F 122-key keyboards and taking them apart to see what is inside? Please don't think I am smoking crack or living in La-La Land to even ask.

Probably Monday, I will re-assemble this thing and see what I can make happen. This has been a very difficult week for me (death in the family), and it would be nice if something worked out nicely.

So what was my question(s)? Is the green board better than the copper one, and how do I utilize/improve the rubber mats?

thanks a lot, folks

Quote from: LETE;431929
You don't need to worry about the thicker coating affecting performance. When the keyboard was designed they would have balanced the gain to account for the distance between the conductors, and capacitive sensors aren't especially sensitive to obstructions anyway. My iphone still works with 9 layers of painter's tape on it.

I'd like to figure out a solution to the decomposed mats as well. I'm sure you can't buy them ready made or anything, but there should be a way to make your own. It's worth looking into.

Quote from: fohat.digs;432044
It might not be all that hard to make one, provided that you had a hole punch of just the right size.

A fresh firm mat might even improve the feel, my daughter has foam art supplies that are probably a very good thickness for this, slightly deeper and firmer than the original.

Exactly what I need, another tedious time-consuming project!

Quote from: LETE;432052
Let's both give it a shot and compare notes. Of course, if we get a proof of concept laid out, it wouldn't be too hard to make a CAD file of the design and send it in to get laser cut for a group buy.

Quote from: fohat.digs;432713
May be getting far enough off-topic to warrant a new thread.

Since I am really fond of the Model F terminal, in spite of my mapping problems, and since I have an extra used board to experiment on, I am considering a bolt mod to tighten this thing up.

This will require drilling the circuit board and the metal, and I don't figure to use too many bolts. In fact, I can't put any where I really want them, scattered among the letter keys, since the barrels are in the way.

Please look at the diagram below, and let me know if this might be a good layout, and/or if the benefit is work wasting a couple of hours on, at all.

Thanks, Harry

(Attachment Link) 28821[/ATTACH]

I think that's an insanely brilliant Idea. Those bolt positions look like they're going to work for you. You can add a few more bolts here or there but the metal frame is rigid and it's curvature works in your favor so I think it will transfer the pressure across the letter key area just fine. The only problem I see is the upper left hand corner. You might be able to reroute that trace that goes around the entire perimeter to free up enough room in the very corner to fit a bolt. It would be tight, and you wouldn't be able to do it if there is another trace on the bottom layer. I'll give that a look later.
« Last Edit: Mon, 17 October 2011, 14:26:23 by LETE »

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #2 on: Mon, 17 October 2011, 16:21:15 »
I don't see any way. I looked at the board, and I want to be careful, since I am afraid of cracking it while drilling.

There is a narrow rectangular space above 1/! and below F2 that might work, but even that seems small. Half a dozen bolts should be plenty, the central area and numpad are what I use regularly anyway, and I really use the Enter on the numpad a lot.

Instead of 50 2mm bolts, I plan to use short #4s with decent-sized washers.
"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24

Offline LETE

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Model F 122 Terminal Mod Planning
« Reply #3 on: Mon, 17 October 2011, 16:43:11 »
Yeah, I'll check into that upper left corner later. I wouldn't mind drilling through a ground trace if I had to. Are you planning on using the tab fastening system or are you going with bolts alone? If you keep the tabs it might be hard to line up the holes for the bolts.

Update:

Good news, it turns out those big obstructions in the upper left are ground traces.

Here is a picture of the top PCB layer with the ground trace highlighted in white.

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Here is a picture of the bottom PCB layer mirrored for your convenience with the ground traces highlighted in white.

[ Guests cannot view attachments ] 28868[/ATTACH]

As you can see there's plenty of space to the left of the function keys for bolts.
« Last Edit: Mon, 17 October 2011, 19:24:15 by LETE »

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #4 on: Thu, 20 October 2011, 09:09:38 »
So I drilled and bolted a spare frame and assembly. It went pretty well, but I am glad I had extra parts because I trashed a couple, due to careless drill work.

Some of the hole locations I indicated on my first drawing need to be adjusted.

#4-40 x 1/2" machine bolts and nuts work well and are just barely long enough. In the upper half of the board, where there is a lot more room below, I will use 3/4" and put rubber washers in the mix.

I am not so sure that it is worth the trouble, I will need to use it for a while to get comfortable.

When and if I get a 1/2" hole punch, I may try to make a replacement mat with "art" foam sheets. If those little "slots" have to be individually cut, it will be a killer. I am hoping that I can make a single "nick" or slice at each location and that will be enough. Over time, the assembly will surely deform the foam the way it needs to be, but it needs to work when you first build it.
"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #5 on: Sat, 05 November 2011, 17:26:33 »
Still haven't found a 1/2" hole punch, so the new rubber mat may not get fabricated any time soon.

I was able to make one of my worn ones work, and I painted the metal plate with several coats of rubber paint on the back side, as well as several coats of bright red on the front.

The bolt mod and flossing went well, I moved a few of the bolt hole locations to avoid hammer plates and traces.

I stuffed the frame with old pillow padding, and this baby rocks!

It is heavy as hell, solid, and moderately quiet, with great tactile feel and little or no resonance.


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"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24

Offline SmallFry

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Model F 122 Terminal Mod Planning
« Reply #6 on: Sat, 05 November 2011, 19:39:09 »
What is flossing the springs mean? That board looks sweet :biggrin: I may have to try to do something like that to my Model M 122, much like your F. See my signature :happy:

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #7 on: Sat, 05 November 2011, 21:20:46 »
I think Ripster explains it in detail somewhere.

You buy the kind of dental floss that has individual pieces with hard ends to thread between small spaces (eg my daughter's braces) and the middle fluffs out to be a few mm in diameter.

That middle section is what you use - you cut it into pieces and thread it into the center of the springs. I get about 7 out of each piece of floss.

If is so light that it does not really affect the action of the springs, but it cuts out the resonance and ringing (pinging), reducing the noise by half and bringing it down to a lower register.

I have done it twice, with the springs out and loose. You can surely do it with the springs mounted in the board, but it may take twice as long.
"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24

Offline LETE

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Model F 122 Terminal Mod Planning
« Reply #8 on: Sun, 06 November 2011, 00:50:34 »
I ordered a hole punch set. I think I'll use a hole punch slightly larger than .5 inches so as to encompass the little tab at the base of each shaft. I don't think it's necessary to meticulously add a little notch to each hole since the shaft base is large enough to still make a complete seal. I should get around to making that mat this week. I have a few questions for you.

Where did you stick the pillow stuffing? I can't see it in there.
Where did you put the bolts?
Did the bolt mod make a difference in feel?
Is it easier to assemble/disassemble with the bolt mod than it was before?
Did you leave the tab attaching mechanism in place?

 I tried the floss dampening trick once, but it messed up the feel of the keyboard for me. Besides I like the racket I make when I type.

Also, I replaced the upper shell of my model F 122 with the shell of an M 122. The model M variant has a more robust upper than the F. It's less prone to cracking, and with some drilling can be fastened in five places instead of the F's three. I had to sacrifice the M keyboard for it's shell but compared to the internals of the model F the M looks like it came out of a happy meal so it was really no big loss. I actually purchased 8 model M's for the sole purpose of being shell donors for my model F's. Sadly most of them don't have the spiffy legs (which I guess I don't use anyway).
« Last Edit: Sun, 06 November 2011, 00:57:34 by LETE »

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #9 on: Sun, 06 November 2011, 09:34:28 »
I have been wondering whether the early version of the M-122 shell would work, I need one, too.

I bought the first (nice) F-122 from Ocean Tech and did not realize how lucky I was to get one that was in good shape throughout. Then I bought a lot of 4 F-122s from Rawko (5 minutes from my office) and they were wrecked. All 4 cases (shells) were broken in some way, usually diagonal breaks from the bottom corners of the key openings out the bottom of the long thin plastic strip at the front. Careful repair jobs using "JB Weld" did not always work and were the wrong color, of course.

There were only 2 spacebars, unfortunately not interchangeable with Ms because the F wire stabilizer is a smaller gauge. 80%-90% of the keys were there, all-in-all it was not a bad buy, but less than I expected.

Big disappointment was the rubber mats. 2 completely disintegrated before I got them off. I did one dry, and soaked one for an hour in hopes that maybe it was glued down with sugar or soda (same thing) and that was maybe a marginal improvement but still did not work. The other 2 came off with a thin rubber layer intact, but the foam was completely deteriorated into a horrible sticky granular mess. One day I will get that hole punch and make a couple of fresh mats.

I have 2 of these F-122s now, one raw and undamped, and one flossed and padded. The raw one has a beautiful clear ringing sound that is great, but I have a wife and 2 kids ......

Padding the case was done in several parts. To partially make up for the missing foam, I spray painted the backplate with several layers of rubber coating, an industrial product made for tools handles and waterproofing. I cut a felt mat to fit the bottom of the metal pan case bottom. I used that rough type of electrician's tape all around the interior assembly and where it contacted the outer case. After I screwed the interior assembly to the case bottom, I tore the polyester pillow fluff into golf ball sized pieces and pushed it into the space between the parts with a chopstick. I used at least a dozen of those which compressed to very little volume. No pictures because it is embarrassingly low-tech and ghetto! I certainly HOPE you don't see it in the finished product!

I thought that I had posted a picture of my bolt locations. I will edit this post later today to show my new scheme. Did it make a difference? I think that it did. The whole bad-ass board is as tight as a drum, and feels like a Sherman tank, but at the cost of some overtones. The feel and click are completely intact.

< Photo deleted - see post below for corrected layout. >

This is my 2nd try. Good thing I had an extra board to experiment with. Ended up moving holes #2 and #3 up to the smaller "throat" because of conflicts with the hammer plates in the number row. Moved #4 and #7 up one row for more clearance with the bottom pan. Moved #9 up one row, because of a conflict with the tab that holds the wire stabilizer. Be careful when you locate #5 because there is an unused hole in the metal plate very near there, and remember to keep away from the wire stabilizer tabs in general.

I used far less bolts than on a Model M, for one reason because there is no room in the middle of the letter keys where you might really want them. I used larger bolts (4-40 American size) and the ones near the bottom (front, spacebar side, whatever you call it) could only be 1/2" long with no washers because there is not much clearance.

From mid-way up (back, whatever) the interior assembly curves away from the case bottom so there was plenty of room for 3/4" bolts and I sandwiched in washers, including rubber washers.

I felt compelled to leave the tabs and slots alone, since that is the alignment process. After slipping Fs apart at least a dozen times, it is getting easier, but it is still a tedious pain. If I intended to do this much more, I might be inclined to get some scrap lumber and build some sort of jig, but then there are the XTs and ATs in addition to the 122s ......

Those tabs that were bent over, to keep everything in place, well, you don't need to do that any more, at least. That was a weird idea anyway, probably makes sense in a factory but surely not intended for humans to have to mess with regularly. At least after you break it free for the first time in nearly 3 decades, it slides on and off a bit easier when it goes back together.

I will be very curious to see how the paint/dye job holds up over time.

Good Luck !
« Last Edit: Sun, 13 November 2011, 09:11:55 by fohat.digs »
"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24

Offline LETE

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Model F 122 Terminal Mod Planning
« Reply #10 on: Sun, 13 November 2011, 00:27:30 »
I'm done punching holes in my 1/16" sheet of neoprene. I just need to reassemble the board. Those plastic shafts fit well enough without an extra little tab being added to each hole, and that was with a 1/2" hole punch. I think I'll get around to putting the thing back together tomorrow, if it fits back together at all. I'm worried the mat might be a little too thick now, with the 1/16" neoprene. If it is I'll have to go right to bolt modding it.

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DIY mats made from 1/16" neoprene

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Ratty old decomposed mat
« Last Edit: Sun, 13 November 2011, 00:30:42 by LETE »

Offline fohat.digs

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Model F 122 Terminal Mod Planning
« Reply #11 on: Sun, 13 November 2011, 09:04:31 »
Good job with that. One day I will try it.

Do you just force the tab to dent the neoprene down?

If the mat is too thick, it is going to be hard to get the plates to slide sideways against each other. I have not figured out how to use additional pressure since it would push the barrels back up. If the barrel tabs are holding it up, at all, they make that issue worse.

The factory mat you show is not so bad. I have taken apart 5 of these, and that mat is better than all but one of the ones I have seen, and better than the 2 "useable" ones, including the one I am typing on now. My first one was really nice, the middle 2 were acceptable, and the last 2 disintegrated into shreds.

I carefully cleaned and flattened it, and gently worked it into place. I am looking forward to having a really nice firm one.

I am working on a good set of instructions to put on the front end of this thread, physical work only. Soarer is the man for the electrics.

Here is my recommended layout for holes for bolt-modding. I differs from what I tried earlier, I made mistakes and good thing I had extra boards. It is hard to understand the relationship between barrel holes, hammers, and electrical traces. They are not as you might expect, trust me.

I used to have another hole on the left side of the spacebar, (#5 in the post above) but that area is very problematic. I think what I show below is plenty. I would love to put bolts between "D" and "E" and between "K" and "I" but there is just no way in hell.

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More to come later.
« Last Edit: Sun, 13 November 2011, 09:17:15 by fohat.digs »
"At Fox News, on talk radio, and on the web, American conservatives have built a communications system that effectively consolidates in-group identity. Much of the time, the talkers and listeners do not themselves understand what they are saying. They use key words and phrases as gang signs: badges of identity that are recognized without necessarily being understood.

Rupert Murdoch, Roger Ailes, and the others have fenced off conservative Americans from the rest of American society. Within that safe space, insiders hear only what is familiar and comforting. When those protected insiders step outside into the larger world, they find themselves completely unprepared for it."

- David Frum - The Atlantic - 2019-11-24