Fixing IBM Model F AT "WEIRD" SPACEBAR

[QWERTZ_]

Hello, recently I purchased IBM Model F AT, I already had F XT before. After trying the F AT, I noticed the Spacebar feels different and "weird" to me, so I'm posting this hoping to find some insight regarding my spacebar.

The video to the Spacebar issue is : https://youtu.be/nmipoWqj8ik

So the issue on the Spacebar is as following :
1. The spacebar on my F AT feels like there's two "tactile" bump to it (you can kindly check the youtube video for the example)
2. The spacebar makes unpleasant noise, unlike the sweet thump on my F XT
3. It feels way stiffer than my F XT spacebar

So, is this normal in the F AT? (I think not, checked several youtube vids and their spacebar is much more pleasant). What might have seems to be the problem? I'm a newbie, so don't have the courage to take apart the keyboard

Hopefully someone can help me with this, as the issue has been bugging me to death
Thanks everybody, cheers from Indonesia

[SOTGO]

I agree that this isn't the normal behavior of the spacebar, but unfortunately model F spacebars can be quite difficult to work on. I think there is a chance that reseating the spring will fix the issue, but removing the spacebar keycap is quite annoying and may require a full disassembly. You can reattach the spacebar without disassembly using string, but this requires drilling a small hole and following the process documented here: https://geekhack.org/index.php?topic=41059.0

[Karmel]

You can reattach the spacebar without disassembly using string, but this requires drilling a small hole and following the process documented here: https://geekhack.org/index.php?topic=41059.0

You could also use this method.

[QWERTZ_]

I agree that this isn't the normal behavior of the spacebar, but unfortunately model F spacebars can be quite difficult to work on. I think there is a chance that reseating the spring will fix the issue, but removing the spacebar keycap is quite annoying and may require a full disassembly. You can reattach the spacebar without disassembly using string, but this requires drilling a small hole and following the process documented here: https://geekhack.org/index.php?topic=41059.0

Thank you for the advice, might be a man and open up this sweet boi! Wish me luck!

[Muirium]

Good luck! Even the case can be a bit tight to get inside, as I found out for myself. Also, once you're into the barrel plate sandwich: beware of the condition of your foam. It's often very crumbly. You probably want to replace it.

Getting used to delving inside your Model Fs is definitely a good thing to practice. You'll be back!

[QWERTZ_]

Good luck! Even the case can be a bit tight to get inside, as I found out for myself. Also, once you're into the barrel plate sandwich: beware of the condition of your foam. It's often very crumbly. You probably want to replace it.

Getting used to delving inside your Model Fs is definitely a good thing to practice. You'll be back!

Oh man, this is really helpful, it's funny you've been in the same situation as me long long time ago
How does the bad boi doing now? You still use it?

[Muirium]

Aye, I do indeed! The board cleaned up real nice, and is among my best feeling and most usable to this day. Let's find a recent pic…


viewtopic.php?p=484834#p484834

Once you're inside, you can modify the layout a bit. I mixed up the numpad so I could have TKL-style arrow keys, and I split Big Ass Enter into ANSI Return and HHKB style Backspace, as I like on my keyboards. You just need to have the right caps available, and enough flippers.

My cable was really janky so I replaced it with a USB C port on the back of the case. I used to run the keyboard with an internal Soarer's converter, but I recently pulled out the original controller and installed an Xwhatsit Model F controller running Pandrew's QMK instead, just like my Kishsaver. The USB C port is a simple internally mounted female C to male micro USB cable, glued in place. A similar trick I did to my NMB. Centrally mounted USB C ports work really nicely on these big boards, especially for clumsy sorts like me who forget just how long those original cords can be!

A bigger mod I'd kinda like to do someday is “the ANSI mod” where you swap out the loooooong spacebar for a Model M spacebar plus two extra mods, like this:



The AT actually has the sense pads for those two extra keys, they're just dormant. This mod requires drilling the plate, so it's more demanding than anything I've done. And I actually quite like the extra heavy AT spacebar feeling, anyway. Those two extra mods would sure be nice, though.

[fohat]

those two extra keys, they're just dormant.
This mod requires drilling the plate

I have done the mod, it is a very good way to go. It takes only middling Dremel skill, cutting out two half-circles a half inch in diameter in metal and some trivial plastic cuts (none of which need to be "clean" and are not visible in the re-assembled keyboard).

I have always wondered why IBM set up those locations, from what I have heard they never actually made any keyboards that utilized them. But apparently those engineers put in a lot of potential Easter eggs "just because" ....

Is that Lenin looking at us from your numpad?

[timw4mail]

I have always wondered why IBM set up those locations, from what I have heard they never actually made any keyboards that utilized them. But apparently those engineers put in a lot of potential Easter eggs "just because" ....

A realistic reason: they had planned to add extra keys, but they were nixed, and it was cheaper to use the board revision with the extra pads than design a new one.

The Model F series was cost-reduced compared to the beam-spring keyboards, but these were not loss-leader peripherals like keyboards and mice are these days.

[Muirium]

Exactly. Design one PCB which supports both layouts, it just makes sense, and gives us a sweet mod, decades later!

As for Lenin, you are quite correct, comrade…

Spoiler:

[Rayndalf]

They got so much mileage out of the Datamaster/5291/F XT assembly and wanted to have more options for later boards using the AT PCB. I don't think they expected to adopt the M so soon after the F AT.