Is it possible to convert an IBM Model M to Model F?

[cheater]

Given that the keycaps are the same, and therefore the parts they slide in (the round shafts the springs are in) are the same profile inside, is the underside of the plate the same between F and M? Could I take a Model M, install F flippers and springs and a self-made PCB, and have a model F? Asking because Model F doesn't come in some layouts and some of the less usual F keyboards fetch stupid prices which I don't want to support.

If they can't be "converted" like that - what are the major issues? I'm pretty handy with a dremel and I have enough chemical supplies here to be able to fabricate sturdy plastic parts by hand that behave like they've been injection molded, but obviously it won't be precision work like eg needed for sliders or for parts that clip into each other.

[Findecanor]

The construction of the barrel plates are different, but whether the shapes are the same, that is the question.
Model F barrels are individual plastic pieces in a metal plate. Model M barrels are a single piece of plastic, with plastic "rivets" penetrating the metal backplate and melted on the other side of it.

Someone has had this idea before: Check out the "Model MF" project.

[TNT]

Aren't those two completely different systems for signal creation? One is based on the change on capacitance due to the hammer connecting two contact plates on the PCB and the other one on closing a circuit between conductive parts on the membrane. That probably means, the electronic circuits on both variants wildly differ from each other. So you would need to rip out the membrane of your M, probably even replace the hammers, attach a custom fit PCB with new contacts, a new, custom made controller circuit, and bolt mod it back together. Even then this frankenstein creation will most likely still not feel like a Model F, because the plates in those are metal and not plastic and the dimensions of the barrels and springs etc are different.

Take everything I say with a grain of salt, I'm not an expert on these boards.

[hellothere]

One is based on the change on capacitance due to the hammer connecting the plates and the other one on closing a circuit between conductive parts on the membrane.

Sounds good.

[TNT]

The construction of the barrel plates are different, but whether the shapes are the same, that is the question.
Model F barrels are individual plastic pieces in a metal plate. Model M barrels are a single piece of plastic, with plastic "rivets" penetrating the metal backplate and melted on the other side of it.

Someone has had this idea before: Check out the "Model MF" project.

Also, this project is insane. I love it

[cheater]

Aren't those two completely different systems for signal creation? One is based on the change on capacitance due to the hammer connecting two contact plates on the PCB (.... a long diatribe ......)

a self-made PCB,

dude. stop yourself sometimes

[cheater]

The construction of the barrel plates are different, but whether the shapes are the same, that is the question.
Model F barrels are individual plastic pieces in a metal plate. Model M barrels are a single piece of plastic, with plastic "rivets" penetrating the metal backplate and melted on the other side of it.

Someone has had this idea before: Check out the "Model MF" project.

Also, this project is insane. I love it

Yep, I love it. It actually answers some questions that I wanted myself. My eventual goal is to make a custom layout F or beamspring, and seeing that there's a bunch of stuff out there being done that saves me a bunch of work, I love it. I had no idea that thread existed - thanks Findecanor!

[TNT]

Aren't those two completely different systems for signal creation? One is based on the change on capacitance due to the hammer connecting two contact plates on the PCB (.... a long diatribe ......)

a self-made PCB,

dude. stop yourself sometimes

To be fair, it was 3 in the morning after a long day. Why call it a diatribe tho, I wasn't trying to be mean, I was just trying to help :/

[Weezer]

Aren't those two completely different systems for signal creation? One is based on the change on capacitance due to the hammer connecting two contact plates on the PCB (.... a long diatribe ......)

a self-made PCB,

dude. stop yourself sometimes

There's no need to be mean. He didn't say anything rude. A conversion like you describe isn't feasible because you'd have to throw out every piece except possibly the case. That's why the MF project takes a ground up approach.

[fohat]

I continue to contend that it is the interplay of tensions and compressions between multiple metal plates that makes the Model F so "alive" and makes is "sing" as people have attempted to describe it.

Barrel stems, springs, pivot plates, those are all secondary - in my opinion.

But I will concede that having the pivot plates (the "feet") gently falling to rest on the pads to achieve capacitance is is inherently less demanding than compressing plastic sheets to make physical contact between printed traces.

[cheater]

So in this thread someone figured out that the model F flippers/springs are fully compatible with M barrel plates, except in some plates you need to modify 4 spots and that's it. So all you need then is a PCB and controller, which is pretty great. The pcb is easy to make.

Conclusion: leaving aside the four flippers that can be resolved, the flippers are compatible.

[Weezer]

Go for it. It's your keyboard.

[Weezer]

I continue to contend that it is the interplay of tensions and compressions between multiple metal plates that makes the Model F so "alive" and makes is "sing" as people have attempted to describe it.

This is interesting. I'm not sure that I agree entirely but I do think that the large pieces of metal help amplify the sound. It sounds like you might think that corrosion or rust on the springs doesn't play a part in the sound, is this accurate?

[zrrion]

The F ET, which has a plastic barrel plate from the factory, is very similar to any other F in sound so I am not sure the barrel assembly is the secret sauce

[Weezer]

The F ET, which has a plastic barrel plate from the factory, is very similar to any other F in sound so I am not sure the barrel assembly is the secret sauce

Hm I'm not familiar with the ET... I know the AT has a metal barrel plate but a plastic bottom case but I'm not sure if that's what you mean.

I think that the top factor in the key sound is the springs though. You can see how much a floss mod changes the sound for example.

[cheater]

The F ET, which has a plastic barrel plate from the factory, is very similar to any other F in sound so I am not sure the barrel assembly is the secret sauce

Do you mean the 122-key Model F? I don't know what the F ET is, sorry.

[fohat]

I'm not sure that I agree entirely

corrosion or rust on the springs

My opinions are based on direct personal experience of completely dis-assembling and re-assembling many Ms and Fs, enough to give me insight into their inner workings.

Can't speak to rust, I have cleaned up some light rust but have always discarded heavily rusted springs.

[zrrion]

Do you mean the 122-key Model F? I don't know what the F ET is, sorry.

ET is for Electronic Typewriter. Its a typewriter sort of in between the selectric and the wheel writer and it uses capacitive buckling springs like an F, but a plastic barrel frame like an M.

[cakeanalytics]

A review of IBM Electronic Typewriter, including typing demo
viewtopic.php?f=62&t=16727&p=466226

[Coeus]

Aren't those two completely different systems for signal creation? One is based on the change on capacitance due to the hammer connecting two contact plates on the PCB and the other one on closing a circuit between conductive parts on the membrane. That probably means, the electronic circuits on both variants wildly differ from each other. So you would need to rip out the membrane of your M, probably even replace the hammers, attach a custom fit PCB with new contacts, a new, custom made controller circuit, and bolt mod it back together. Even then this frankenstein creation will most likely still not feel like a Model F, because the plates in those are metal and not plastic and the dimensions of the barrels and springs etc are different.

It is the dimensions of the barrels and plates that matter here, surely.

A while ago now, I read the advertising for the recreated model F project. After having said that the model F feel was even better than the model M, I was then disappointed to find that the enhanced layout that has since become the standard was not one of those available. There would have been the chance to create something really unique - something that is not available 2nd hand on eBay at any price. So I got a 2nd hand Model F instead.

But also, the recreated model F project said that most of the cost was in things like the tooling for making the case and mechanical parts. By comparison PCBs seem to be reasonably cheap. I haven't order one myself but I know people who have designed new hardware, often to go with old computers, who have.

So if the intention is built a model F with the enhanced layout by using a model M as the starting point, that has the advantage that the case already has the right apertures for that layout. If the barrel plate can be re-used then that's another big step forwards.

[fohat]

I was then disappointed to find that the enhanced layout that has since become the standard was not one of those available.

You can get very close to a standard ANSI layout.

https://geekhack.org/index.php?topic=48 ... msg1048948

[Reshala]

As for the PCB, there's somebody in China who has already made some capacitive ones for SSK.

[cheater]

As for the PCB, there's somebody in China who has already made some capacitive ones for SSK.

Oh that's pretty cool.

[Coeus]

You can get very close to a standard ANSI layout.

https://geekhack.org/index.php?topic=48 ... msg1048948

Yes, the 122 key terminal keyboard is close but the model F version is not common and those that are around are much more expensive than the recreated model F. The Model M version of the 122 key is more common.