IBM MODEL F AT vs XT

[THATGUY69]

I recently purchased a model F At. I bought a model F xt a while back to see if I'd like the switch in it and surprise surprise, they are currently my favorite switch. On the F At I noticed that it has a different feel to the keys, at least this one does. They are slightly stiffer and aren't as crisp as the F xt. Is it a current consensus that the switches feel the same in each of the boards or are they know to have a different feel. Im curious if the feel of the switches is different due to wear on the boards. I Definitely know that the build quality is definitely worse in the F At, but I'm pretty sure nothing on this planet is built as well as the F xt

[seebart]

On the F At I noticed that it has a different feel to the keys, at least this one does.

You mean different to the XT? Yes I can confirm that. I'd still say the AT is pretty solid but yes nothing like the XT that is built like a tank. Now if you're having inconsistent key feel on your AT itself you may have to take a look.

[ryvnf]

IBM 4704 might be something on this planet that is built better than F xt. Would be nice if someone who has also tried a 4704 can comment on how they feel and compare to AT and XT.

[alh84001]

While we're on the topic, does anyone else's 4704 have quite a different feel to other model Fs? My F107 feels noticeably stiffer.

[Sigmoid]

While there are some differences between the XT and AT components, the mechanism is mostly identical. "Wear" as such isn't a huge factor in Model Fs, but the condition of the foam padding, and dust / muck definitely is.

Personally I'm on the opinion that any Model F's today need to be completely disassembled, cleaned out, the flippers carefully washed in a light detergent, the springs given a bath in machine oil, the keycaps and barrels given a ride in a salad spinner with dishwasher fluid, the PCB cleaned with alcohol swab, and the foam padding - which has probably totally decomposed into sticky muck by this time - completely replaced (I personally used a 1/16" thick silicone foam mat cut to size with scissors and holes cut with a set of leather punchers).

EDIT: See my XT refurbishment blog thread from two years ago for reference: keyboards-f2/model-f-xt-refurbishing-t10481.html

[THATGUY69]

On the F At I noticed that it has a different feel to the keys, at least this one does.

You mean different to the XT? Yes I can confirm that. I'd still say the AT is pretty solid but yes nothing like the XT that is built like a tank. Now if you're having inconsistent key feel on your AT itself you may have to take a look.

Okay, cool, thanks for letting me know, but I have one more question you could maybe help me out with if you have ever encountered a 122 key model F . How does a 122 key model F compare to the other two boards? Is it more like a Xt or At board when it comes down to key feel? I'm on a quest to find the best model F

[THATGUY69]

While there are some differences between the XT and AT components, the mechanism is mostly identical. "Wear" as such isn't a huge factor in Model Fs, but the condition of the foam padding, and dust / muck definitely is.

Personally I'm on the opinion that any Model F's today need to be completely disassembled, cleaned out, the flippers carefully washed in a light detergent, the springs given a bath in machine oil, the keycaps and barrels given a ride in a salad spinner with dishwasher fluid, the PCB cleaned with alcohol swab, and the foam padding - which has probably totally decomposed into sticky muck by this time - completely replaced (I personally used a 1/16" thick silicone foam mat cut to size with scissors and holes cut with a set of leather punchers).

EDIT: See my XT refurbishment blog thread from two years ago for reference: keyboards-f2/model-f-xt-refurbishing-t10481.html

Quick question about that, I will probably end up doing that, just because the upper barrel plate is rusting a bit(not too bad but it bothers me anyways ) and the mat is probably turning to mush anyways. Where did you find the silicone mat at to purchase?

[fohat]

Depending on what layout you prefer, my guide may be of some help.

workshop-f7/ibm-model-f-122-key-termina ... rry%20ansi

The compact size and narrowness of the XT probably make it the most tight and crisp of all the variants.

The metal case of the 4704s is a light and soft metal, and the internal assembly attaches to the top case shell. I feel sure that the steel bottom pans of the XT and 122 are more rigid and heavy.

[seebart]

IBM 4704 might be something on this planet that is built better than F xt. Would be nice if someone who has also tried a 4704 can comment on how they feel and compare to AT and XT.

I would not doubt that at all, unfortunately I don't own one.

On the F At I noticed that it has a different feel to the keys, at least this one does.

You mean different to the XT? Yes I can confirm that. I'd still say the AT is pretty solid but yes nothing like the XT that is built like a tank. Now if you're having inconsistent key feel on your AT itself you may have to take a look.

Okay, cool, thanks for letting me know, but I have one more question you could maybe help me out with if you have ever encountered a 122 key model F . How does a 122 key model F compare to the other two boards? Is it more like a Xt or At board when it comes down to key feel? I'm on a quest to find the best model F

That's a respecable quest! I can only speak from what I own and a F 122 is not in my possesion. Fohat...

[Sigmoid]

Quick question about that, I will probably end up doing that, just because the upper barrel plate is rusting a bit(not too bad but it bothers me anyways ) and the mat is probably turning to mush anyways. Where did you find the silicone mat at to purchase?

I used McMaster Carr, which is a perfect source for anything mechanical in the US. If you're located somewhere else, it should be easy to find a similar supplier. Do take care with silicone foam though, it's ridiculously electric - I had to coat them with a spray-on static dissipative.

[__red__]

I believe I have several of each upstairs, lemme check.

I will say however that one of my 4704s feels completely different to the others. brb...

[__red__]

Okay, I pulled from storage the following:

3 x IBM Model F-122
3 x IBM Model F 4704 (107)
3 x IBM Model F XT
1 x IBM Model F Bigfoot
(I don't seem to have an AT to hand anymore, sorry) :-/

They're all variable condition but if I were to rank them in 'tightness' on average it would be Bigfoot, 4704, XT, F-122. I will note that there is a fair amount of overlap. For example, one of the F-122s is tighter than one of the 4704s so I personally believe that the condition of the keyboard is a larger impact than the difference in the models. One of my F-122s is so loose it sounds less like a keyboard and more like a resonator-guitar

The tightest is almost certainly the one 4704 whose foam I had replaced with craft foam. The foam has near zero give.

For feel / sound, foam is a HUGE factor. On the F-122 having consistent response across all rows is a lot harder as you've got further to try and keep within tolerance.

[Chyros]

Depending on what layout you prefer, my guide may be of some help.

workshop-f7/ibm-model-f-122-key-termina ... rry%20ansi

The compact size and narrowness of the XT probably make it the most tight and crisp of all the variants.

The metal case of the 4704s is a light and soft metal, and the internal assembly attaches to the top case shell. I feel sure that the steel bottom pans of the XT and 122 are more rigid and heavy.

Someone mentioned the 4707 shell is zinc, which would explain the softer feel. Obviously the steel plates of the XT and F122 would be much stronger than a zinc one.

Still, the F107 is one of the boards I've been looking for for a while - they seem quite interesting.

Across the F122, F XT and F AT I haven't found a significant difference in feel - however the relative stiffnesses of the chassis does impact sound and key firmness slightly.

[seebart]

Of my F's the most solid feeling is the XT, but I prefer the AT and the Displaywriter. The bottom end is the 3178 because the case is so flimsy compared to all other F's I own. I'd love to get a F107.

[fohat]

On the F-122 having consistent response across all rows is a lot harder as you've got further to try and keep within tolerance.

As I have discussed several times, for the last couple of years I have added 2-4 "bolts" (M3x12 (or 4-40x1/2) machine screws with nuts and washers) to every Model F refurb that I have done and I believe that it makes a tremendous difference, especially on the 122 since it is so much taller. And particularly if the foam has been replaced with something thicker and/or stiffer it is imperative that the plates be pulled deep into the concave surface. Unlike my Model M bolt mod recommendation where I advise you to just tighten the screws lightly, I crank these down pretty snug.

My preferred locations on the 122-key are (1) in the center of the square formed by left-F6-CapsLock-and-leftF8-Left Shift, (2) between upper 5 and upper F5, (3) between upper 0 and upper F10, and (4) right of Enter and diagonally above left arrow. Of course choose these locations by eyeball on the PCB board to avoid hitting the traces!

[pixelheresy]

Oh you all... the worse model of the Model F is like saying the shittier Rolls Royce.

Actually, since you guys know... the caps and stems are Model M compatible, right? Every once and a while come across Model F boards for cheaper (but not cheap) with missing caps or legends in French or Italian, so was curious about getting more reasonably price replacement parts, rather than hoping for "dead man's boots" on another Model F.

[alh84001]

Yes, they are compatible. However, print may be sufficiently different, so if you have OCD, that might not work. Also, you may feel a difference between one-piece and two-piece keycaps as well.

[pixelheresy]

Yes, they are compatible. However, print may be sufficiently different, so if you have OCD, that might not work. Also, you may feel a difference between one-piece and two-piece keycaps as well.

Good to know.

Seriously, if I can find a Model F in good condition, I would happily just get a whole replacement Model M set from Unicomp and call it a day (and try to scout out proper replacements later). That keyboard is all about feel and build quality, so even if I had one or two keys that looked off (but felt great), I am less and purist and more a typist . Sure, that is like having a Rolls Royce with an off-color bumper or something, but who gives a crap if I'm out there driving a Rolls

Knowing that the 1-piece vs. 2-piece caps feel different is good to know. Make sense, though, but may not have thought about that immediately.

[__red__]

Still, the F107 is one of the boards I've been looking for for a while - they seem quite interesting.

I can try and ship you one to review but I'll want you to ship it back

In all seriousness though... if I were to send it, would you want one unmolested or one I'd worked on?

[Sigmoid]

Seriously, if I can find a Model F in good condition, I would happily just get a whole replacement Model M set from Unicomp and call it a day (and try to scout out proper replacements later). That keyboard is all about feel and build quality, so even if I had one or two keys that looked off (but felt great), I am less and purist and more a typist . Sure, that is like having a Rolls Royce with an off-color bumper or something, but who gives a crap if I'm out there driving a Rolls

Knowing that the 1-piece vs. 2-piece caps feel different is good to know. Make sense, though, but may not have thought about that immediately.

Actually, legends and two-piece caps are the least of your worries, at least on older Model Fs (especially the Bigfoot and XT). The wide keycaps are incompatible between these and any Model M keyboard. Model Ms, and as far as I know, some later Fs have multi-plunger wide keycaps, and barrels for these "stabilizer" plungers.

Not so on older Model Fs. You always have a CENTER plunger, and the key surface is stepped to stabilize. The only key that has any kind of actual stabilizer on these keyboards is the Space bar. The steel plate and PCB naturally mirrors this arrangement, so it's impossible to fit a Model M keycap of equivalent size. You can of course fit a 1u Model M keycap, but it will look ugly, and probably be uncomfortable.

As a solution we could model these keycaps, and try to 3d print Model M-style clip-on keytops of such form factors... but Nylon isn't PBT. :/

[alh84001]

Knowing that the 1-piece vs. 2-piece caps feel different is good to know. Make sense, though, but may not have thought about that immediately.

They may or they may not. Jury is still out there on whether it's placebo effect or not

[seebart]

Knowing that the 1-piece vs. 2-piece caps feel different is good to know. Make sense, though, but may not have thought about that immediately.

They may or they may not. Jury is still out there on whether it's placebo effect or not

If they do feel different I bet it's minimal. I could test this...nah better post some more meme's.

[alh84001]

[seebart]

402f13c58cade62e7eed27bb453581beb6553e9912cb602170475f72045765db.jpg (49.6 KiB) Viewed 9586 times

[emdude]

However, print may be sufficiently different, so if you have OCD, that might not work.

There is definitely a noticeable difference between "generations" of buckling spring caps, especially easy to see if you compare Model F XT and late Lexmark Model M ones.

It is a big big pet peeve of mine when people mix and match caps from different models!

Unicomp caps are adequate.. if you use an entire set. The keycap color (their "pebble" in particular, gross!) is quite different from what was originally used.

[Chyros]

Still, the F107 is one of the boards I've been looking for for a while - they seem quite interesting.

I can try and ship you one to review but I'll want you to ship it back

In all seriousness though... if I were to send it, would you want one unmolested or one I'd worked on?

I'm not great at converterting, so I'd preferably have a converted one. Thanks though, but shipping would be so much that I'd rather save the shipping money to try and buy one for myself!

[__red__]

I'm actually considering selling two of my 4704s to fund the purchase of an Injection Moulding machine.

I chatted with one vendor on the subject and they'll make me a simple mold with the purchase of one of their machines. This is screaming for the first iteration of MX caps on top of F-stems.

[sgtpopwell]

...This is screaming for the first iteration of MX caps on top of F-stems.

YES! I was just thinking about this last week. I just have no real manufacturing experience at all but it seems like it should be possible. I think injection molding might be the way to go as 3d printing would not be precise enough. Comparing some of my spare MX keycaps to some spare BS keycaps, it seems like there would be at least a 3 or 4 mm rise just because of the inherent design of the female end of the BS stem.

[Sigmoid]

afaik @lot_lizard has a working prototype...

workshop-f7/remodeling-the-model-m-t13796.html

[Touch_It]

While we're on the topic, does anyone else's 4704 have quite a different feel to other model Fs? My F107 feels noticeably stiffer.

My F4704 feels far less pingy than my F122. I think that this is due to the foam being too thin and me putting the upper and lower plates back together oddly. need to re-open it up. The ping adds considerably to the overall "feel" of the board imo. Between a XT, 122, 4704 and a 3178, they all felt more or less identical, with the 3178 maybe feeling the most flimsy, case wise, but key feel all felt the same. (before i restored my 107 key).