Topre Capacitive Switches and Longevity

[ozar]

Has anyone here ever actually worn out a keyboard that uses Topre capacitive switches?

Note that I'm not talking about breaking or screwing up the board because of some modification or haphazard handling, but I mean literally worn it out through heavy usage.

What I'm wondering about is how these switches might actually behave once they are worn out?

Do any of you happen to know?

[lam47]

Well I have only pressed my keys about 29,999,999 times so I am not sure I want to try the 30 millionth time in case I get some of that nasty sh*t chattering.

But no I doubt there is one that has worn out. It might be worth looking into the degradation of some older capacitive boards. If they use the same sort of rubber.

[xsphat]

Yeah, I don't think you'll find anyone who has worn out one of these babys. Not over here at least.

[ozar]

Yeah, I don't think you'll find anyone who has worn out one of these babys. Not over here at least.

Yes, xsphat - I really figured if anyone here had worn one out it might be you.

Surely a few long time users of the HHKB Pro have typed countless hours on one and then have decided that it has served its purpose and gone on to purchase a new one.

I'm guessing the switches would take on a rather mushy feel like that of a bad rubber dome board, but don't know.  Perhaps someone using the search engines will find this thread and stop by to fill us in on what to expect if any of us ever put in enough strokes to actually make it happen.

[cmr]

it seems to me that you might eventually wear the dielectric off, or destroy the rubber dome or the spring, but i don't think there's a way to wear out the actual capacitor unless you somehow managed to corrode them

[xsphat]

I'm on my third Torpe made board in two years, my previous two are in use by members here, so I can't help you. If this keyboard begins to fail or screw up at all, I'll buy another right off. I don't think that'll happen any time soon though (better not for the price I paid).

[ozar]

I'm still not sure how long Topre switches might actually last in the long run, but I did notice right away that the switches on my new HHKB Pro 2 and Realforce 87U boards felt quite a bit tighter than those on my used HHKB Pro2 board, that isn't even a year old, yet.

Perhaps they loosen up to a certain point and then stay that way until failure, or maybe they just keep on getting looser and looser with heavy usage until they fail.  I'm preferring the tighter feel of the newer boards at the moment, but should I ever figure out an actual pattern of wear with these switches, I'll report back with the findings.

[bigpook]

correct me if I am wrong here but what are we looking at with the Topre keys?

A spring and a rubber dome. I would think the rubber dome would degrade before the spring wore out. But I could be wrong. Either way, I would think it would be years before it became a problem.

[ozar]

So, I wonder if it's the rubber domes degrading, the springs loosening up, or the keycaps just not fitting as tightly anymore that causes the looser feeling with the keys on the used board, or perhaps it's simply a combination of all three?

Don't know just yet where any long term wear will occur, but if the keys continue to loosen up over the years, I'd be a little worried because I do prefer the tighter feel of the new boards.  It's probably going to take some heavy typing over a period of a few years to know for sure.

[Korbin]

I would guess that the reason why it is so hard to tell how long it would take for a topre switch to fail is because if you campare the longevity of a membrane board what is the first thing to fail? The contact point. Since Topre switches touch nothing at the actuation point it would be hard to assess what the highest point of failure would be. Maybe the electric capacitance sensor maybe?

I'm just taking a guess though.

[patrickgeekhack]

I've been thinking about the longevity of the Topre switches for a while (like many who want to try one at some point). Then I realised that many people have been using their plain rubber dome keyboards for years. Maybe they are not as good as they used to be when new, but they still work. At work, there are some rubber domes which are still being used even after more than eight years. My colleague is still using the first Microsoft Natural keyboard. He has been using the same keyboard before I started on my present job (8 years).

EDIT: If one can get 10 years out of a Topre which cost around USD $228, the keyboard would have cost USD $22.80 per year. Not bad for a good keyboard.

[patrickgeekhack]

Plus a standard rubber dome you're mushing the thing all to hell just to get the switch to register.  With a Topre you have a capacitive switch design that doesn't require it AND a spring that should increase longevity.  I wouldn't be surprised if a heavy typist on a Model M doesn't feel a difference in springs after that amount of time as well.

Better things to worry about.  Like where you put your Coke can.

Just get another can. Question for you. Since you've had the chance to try both the Topre and the blue cherries, which one do you prefer and why?

[quadibloc]

Since the switch is a non-contact capacitative switch, it might well be reasonable to say that it "never" wears out. However, there is still a spring - and a rubber cone - in the switch as well, to provide tactile feedback, and to push the key back up after you push it down. Those things are moving parts, and experience flexure, so not only can they wear out, they will, if the keyboard is used enough. That this "enough" might exceed the 50 million keypress life quoted for today's Cherry switches, though, is quite possible.

I suppose that if a key instead operated a mechanical linkage that lifted a weight against gravity, the expected lifetime could be made considerably longer. Finally, a steampunk project with some practical usefulness!

[keyb_gr]

I suppose that if a key instead operated a mechanical linkage that lifted a weight against gravity, the expected lifetime could be made considerably longer. Finally, a steampunk project with some practical usefulness!

That would, however, mean you'd either have to store some pretty lengthy levers somewhere or end up with a severely heavy keyboard - a good 100 times 50g means 5 kg for key weights alone. Plus you'd still have a linear characteristic only. For offset linear with spring support you'd still have a good bit of weight there.

MX blacks aren't looking so bad compared to that.

[rdh]

That would, however, mean you'd either have to store some pretty lengthy levers somewhere or end up with a severely heavy keyboard

Nearly all keyboards still have the rows of keys offset sideways from
each other, which was originally to make room for levers.
I'd bet lots of mechanical typewriters used gravity instead of springs
to return the keys.

On the other hand, the keys usually had a lot longer travel than 4 mm,
and probably didn't return very quickly, either.

[rdh]

Plus you'd still have a linear characteristic only.

On the manual typewriters, you got audible feedback when the typebar
hit the platen, but you could avoid bottoming out with a little pratice,
because inertia would carry the typeface forward.

A keyboard using weights instead of springs would similarly have more inertia
during the keypresses, so the force you'd feel with your fingertips would vary
depending on how quickly you strike the keys.

Linear, but with a somewhat different feel than spring-based switches, I think.

[keyb_gr]

A keyboard using weights instead of springs would similarly have more inertia
during the keypresses, so the force you'd feel with your fingertips would vary
depending on how quickly you strike the keys.

And I'm not sure whether that would be a good thing. I guess not, especially if you're a fast typist.

[rdjack21]

I like the Blue Cherry board better.  Like most people, I think a clicky tactile board is the way to go.  I mean,  the whole idea is getting feedback when you press something.  Don't have to explain that to a musician.  

I alternate a LOT though.  If my hands are tired I will switch in the 87U.

As a counter I prefer the Topre boards. And as a person in the minority I prefer a quiter board that means I prever a brown cherry over the blue cherry board. But when I'm feeling the need to type on something that makes a racket then I pick up the Model M because I find the nosie the Model M makes to be more pleasing to the ear. Where as the high pitched rattling of the blue cherry just gets on my nerves after a little while.

[patrickgeekhack]

As a counter I prefer the Topre boards. And as a person in the minority I prefer a quiter board that means I prever a brown cherry over the blue cherry board. But when I'm feeling the need to type on something that makes a racket then I pick up the Model M because I find the nosie the Model M makes to be more pleasing to the ear. Where as the high pitched rattling of the blue cherry just gets on my nerves after a little while.

I guess I'll never the know what a Topre feels like until I try one for myself. As you probably know, I am a big blue Cherries fan.

[MsKeyboard]

patrickgeekhack,

About the only way I can describe typing on a Realforce is to compare it running your finger through some keys on a high end piano.  You don't really bottom out the key, the action comes up and meets you half way.

I had spent a lot of time on the Modular Mac lately, in Blue cherry, and I am now really enjoying the Realforce.  I was concerned from all the discussions here that I would find problems with the "light" weighting, but I am not having that issue.

I do not spend near the time on a keyboard that some of the other members here do, but I have had the opportunity to try just about anything on the market, and some that never made it.  There are a lot of great keyboards, and somebody out there will just love each and every one.  Don't let someone else make up your mind.  That is what is so great about this forum, lots of opinions, lots of testing, and everyone feels open enough to share their likes and dislikes. Absolutely no lack of knowledge here.

Come by sometime, and I will let you try any keyboard we have.

[rdjack21]

I guess I'll never the know what a Topre feels like until I try one for myself. As you probably know, I am a big blue Cherries fan.

The question then is how do you like brown cherry? The Feel of the Topre boards is hard to describe and you truly don't know what that feel is until you type on one for a week or so to let it settle in. Some people like them and some don't. If you really like an audiable click you may not like it because it is a very quit board. But on the other hand if you like cherry browns or even black Alps you may like the Topre.

But on another note. If you are happy with the blues stay with what you like. If they feel lacking in some way then contiue looking. Because the Topre boards are so expensive I tend to think you should try them last that way when you evaluate it you will know if the extra cost is worth it to you or could you settle for a cheaper board. To me they are worth the cost but not every one feels that way. I primarily ended up on the Topre because the heaver boards hurt my fingers after an hour or so (BS and White Alps). Blue cherry switches produce a really high pitch click that gets on my nervs after a while and for some reason I don't type with confidance on them. Brown cherry's are ok and I could live with them but at the time I bought my brown cherry board I had also ordered a Topre. I had the Brown for about a week before the Topre showed up and once I put my fingers on it there was not going back for me. So now my wallet has been depleted and will continue to be depleted until I get most if not all of the Topre variants.

[patrickgeekhack]

patrickgeekhack,

About the only way I can describe typing on a Realforce is to compare it running your finger through some keys on a high end piano.  You don't really bottom out the key, the action comes up and meets you half way.

I had spent a lot of time on the Modular Mac lately, in Blue cherry, and I am now really enjoying the Realforce.  I was concerned from all the discussions here that I would find problems with the "light" weighting, but I am not having that issue.

I do not spend near the time on a keyboard that some of the other members here do, but I have had the opportunity to try just about anything on the market, and some that never made it.  There are a lot of great keyboards, and somebody out there will just love each and every one.  Don't let someone else make up your mind.  That is what is so great about this forum, lots of opinions, lots of testing, and everyone feels open enough to share their likes and dislikes. Absolutely no lack of knowledge here.

Come by sometime, and I will let you try any keyboard we have.

Thanks. Are you in the US?

[patrickgeekhack]

The question then is how do you like brown cherry? The Feel of the Topre boards is hard to describe and you truly don't know what that feel is until you type on one for a week or so to let it settle in. Some people like them and some don't. If you really like an audiable click you may not like it because it is a very quit board. But on the other hand if you like cherry browns or even black Alps you may like the Topre.

But on another note. If you are happy with the blues stay with what you like. If they feel lacking in some way then contiue looking. Because the Topre boards are so expensive I tend to think you should try them last that way when you evaluate it you will know if the extra cost is worth it to you or could you settle for a cheaper board. To me they are worth the cost but not every one feels that way. I primarily ended up on the Topre because the heaver boards hurt my fingers after an hour or so (BS and White Alps). Blue cherry switches produce a really high pitch click that gets on my nervs after a while and for some reason I don't type with confidance on them. Brown cherry's are ok and I could live with them but at the time I bought my brown cherry board I had also ordered a Topre. I had the Brown for about a week before the Topre showed up and once I put my fingers on it there was not going back for me. So now my wallet has been depleted and will continue to be depleted until I get most if not all of the Topre variants.

That's the problem. I don't know how the brown cherries feel like because I don't own one yet. This is why I'm also considering a Filco with brown cherries, but I can only buy one keyboard at a time :-(

[rdjack21]

That's the problem. I don't know how the brown cherries feel like because I don't own one yet. This is why I'm also considering a Filco with brown cherries, but I can only buy one keyboard at a time :-(

Get a cheap Compaq MX11800 to try them on. That is what I did before I got the Filco. I will probably put mine in the market place this week some time. The feel on the Compaq is pretty much the same as the Filco but the layout is not all that great.

[MsKeyboard]

Patrick,

Yes, we are in Beautiful Northern Arizona, Near Sedona.  The weather is a little warm right now, but still nice.  If I remember right, you are in Canada?

No better excuse to take a holiday, come over and try some boards, play tourist.

Later........

[timw4mail]

Of course, there isn't any good keyboard supplier, or at least none that I'm aware of, in Michigan.

[MsKeyboard]

Ahh! Ripster, you are familiar with our famous "Sedona" vortex's.  Can't guarantee their existence, but any residual "power" from being momentarily in our custody is transfered to the customer, free of charge.

As for D V C, it is latin for "Diligentia - Vis - Celeritas" – "Accuracy - Power - Speed".  Did not like my old motto, but should probably change it again.

[patrickgeekhack]

Patrick,

Yes, we are in Beautiful Northern Arizona, Near Sedona.  The weather is a little warm right now, but still nice.  If I remember right, you are in Canada?

No better excuse to take a holiday, come over and try some boards, play tourist.

Later........

I only wish  I could take a holiday, but I will have to pay for 3 persons, well 2.25 persons (wife, daughter and I). But, I've already used my vacation days this year to go there.

Besides, by the time I've paid for the trip and accommodation, I won't have any money left to buy keyboards :-)

Your offer is very tempting. If money was not a problem I would be in Arizona soon :-)

[patrickgeekhack]

Get a cheap Compaq MX11800 to try them on. That is what I did before I got the Filco. I will probably put mine in the market place this week some time. The feel on the Compaq is pretty much the same as the Filco but the layout is not all that great.

Shipping cost makes buying used keyboard less attractive for me. USPS will charge $30.

[patrickgeekhack]

There are quite some thread about Topre that I don't know where I should post this question (mainly because I participated in quite a few of them).

I know it's said already that there is a subtle tactile point on Topre. It's has also been said that the keys will fire about midway through the travel distance. My question is, does the tactile point coincided with the key firing? They are about the same on the Alps, Cherry and Buckling spring.

I've read somewhere that capacitive switches design does not have tactile point and therefore tactile point for user feed back had to be introduced by some other mechanism.

[itlnstln]

There are quite some thread about Topre that I don't know where I should post this question (mainly because I participated in quite a few of them).
 
I know it's said already that there is a subtle tactile point on Topre. It's has also been said that the keys will fire about midway through the travel distance. My question is, does the tactile point coincided with the key firing? They are about the same on the Alps, Cherry and Buckling spring.
 
I've read somewhere that capacitive switches design does not have tactile point and therefore tactile point for user feed back had to be introduced by some other mechanism.

Apparently, there are several (many?) ways to design a capacitive switch mechanism.  That said, other than BS perhaps, all switches' (that I can think of) tactile points are "artificial."  The tactility in an Alps switch is created by the leaf in the switch; there were linear Alps as well (yellow, I think) with the same basic design as the whites and blacks.  Same with Cherrys.  The tactility is determined be the shape of the slider, but it is not inherent to the switching mechanism itself.  Again, in the Topre, the rubber domes' function is to provide tactility and resistance, but the tactility is not part and parcel to the function of the switch.

[patrickgeekhack]

Apparently, there are several (many?) ways to design a capacitive switch mechanism.  That said, other than BS perhaps, all switches' (that I can think of) tactile points are "artificial."  The tactility in an Alps switch is created by the leaf in the switch; there were linear Alps as well (yellow, I think) with the same basic design as the whites and blacks.  Same with Cherrys.  The tactility is determined be the shape of the slider, but it is not inherent to the switching mechanism itself.  Again, in the Topre, the rubber domes' function is to provide tactility and resistance, but the tactility is not part and parcel to the function of the switch.

It's true that the click in clicky switches is artificially introduced. This is why I was wondering if Topre managed to synchronize the click with the tactile point of the rubber domes. I doubt the tactile feel comes from the springs.

[rdjack21]

Ever since I noticed that you asked this question I've been typing and feeling when the key I am hitting at a particular moment registers and when hit the tactile bump in the key (sorry that is the best I could do because Topre switches don't really feel like a mechanical switch or a rubber dome either but it does have a feel when you would think that a key press should be activated) . And I think they have pretty much nailed it when pressing the key at a normal speed and at slow speed. But when you press the key as slow as you can key registration varies somewhat why it does I'm not sure but I bet it has to do with the tolerances in the spring and in the firmware of the board.

[patrickgeekhack]

Ever since I noticed that you asked this question I've been typing and feeling when the key I am hitting at a particular moment registers and when hit the tactile bump in the key (sorry that is the best I could do because Topre switches don't really feel like a mechanical switch or a rubber dome either but it does have a feel when you would think that a key press should be activated) . And I think they have pretty much nailed it when pressing the key at a normal speed and at slow speed. But when you press the key as slow as you can key registration varies somewhat why it does I'm not sure but I bet it has to do with the tolerances in the spring and in the firmware of the board.

Thanks for testing this. I guess key activation is based on typing speed.

[Bollwerk]

In the Topre-discription it is said, that Topre has originally been used by terminalboards in Tokyo.

Has anyone seen such a thing yet?

[rdjack21]

Thanks for testing this. I guess key activation is based on typing speed.

I think it has to do more with the sampling rate they use for measuring the capacitance of the spring. So when you are typing at a normal rate it hits pretty much dead on. But when you really slow it down it will register the key closer to the top of the capacitance thresh hold which may be a little sooner than the tactile bump. This is all conjecture but it is what I think is happening.

[AndrewZorn]

thought it would be better to bump this than to start another thread, but...

I am still abouuuut to get something, and when looking around saw this on YouTube (I know, bear with me):

http://www.youtube.com/watch?v=KmsaAgY_22I

Key Specification
Electric capacitance system (4.0 mm stroke)
Cylindrical step sculpture
19.05 mm pitch

Load of key
45±15g
※According to strength of each finger.

Key Life Expectancy
30 million keystrokes or more
※The durability of the membrane system is about 10 million strokes.

Key top print
sublimation print
※It never disappears because ink soaks into the keytop.

Raw material of key
PBT(polybutylene terephthalate)
※Durability is higher than ABS.

Weight
1.2 or 1.5kg
※It stabilizes because there is an iron plate in the inside and the rigidity is also high.

Other
No chattering
6 key rollover(USB model) or N key rollover(PS/2 model)
There is "101 ASCII layout model", too.(PS/2 model)

I haven't watched the video, but what grabs my attention is the bolded part.  This is what I keep fearing.  How can a normal membrane last so short (one of the big talking points in a "MECHANICAL" keyboard), but the rubber in a Topre last so long?

I know 10m is still a lot but the fact that it is rated as being significantly less durable than its cheaper contenders is not reassuring...

[patrickgeekhack]

thought it would be better to bump this than to start another thread, but...

I am still abouuuut to get something, and when looking around saw this on YouTube (I know, bear with me):

I haven't watched the video, but what grabs my attention is the bolded part.  This is what I keep fearing.  How can a normal membrane last so short (one of the big talking points in a "MECHANICAL" keyboard), but the rubber in a Topre last so long?

I know 10m is still a lot but the fact that it is rated as being significantly less durable than its cheaper contenders is not reassuring...

I initially had the same reaction. But, I think she's was trying to say that a regular rubber dome keyboard durability is 10 million but the Topre switches can last 30m press.

[AndrewZorn]

aaaah didnt think about it that way...

I thought (as you already know) that membrane was mentioned separately in order to suggest that the spring or something is the only part that will make it to 30m.

[takasta]

I own a Topre myself, and i'm not too sure why either. Rubber dome keyboards tend to wear down after couple months of typing and you can feel them being different. However with mechanical and topre key switches, the typing feeling pretty much feels the same ever since day 1 of buying the keyboard. Topre key switches have a spring underneath which i guess gives it that durability. Not sure about that, but i'm pretty sure that your rubber dome keyboards don't have a spring underneath each of the keys haha. It's pretty much smoosh, smoosh. Personally i own 2 cherry blue boards, and a brown board. Personally favorite has got to be the realforce though hands down. I watched alot of Topre videos before actually purchasing my 1st Realforce. I does give you a very good feel of what the keyboard feels like just hearing it haha. When i finally went to japan and got to try all the different HHKB / Realforce, i felt like I was in heaven haha finally trying them all out. Too bad i didn't see an 87U though, only an 86U. I finally settled on a 103UB. Whilst not as portable, it still pleases me just as much. If you're gonna get a keyboard, save up and get a RF. You won't regret it. + I don't mind the numpad since i play DOTA and it comes in handy quite alot haha.

[Rajagra]

Cheap membrane keyboards push two layers of the membrane together to make electrical contact. The contact areas can physically wear out, leading to poor conductivity so they stop working. Since Topre switches are capacitive, that isn't an issue.

EDIT> NVM, talking at cross purposes I suspect.

[rdjack21]

The Topre keyboards do not have a membrane in them. If you really want to understand how the switch is put together go take a look at this wiki page Topre/Realforce Reference -all things topre. It should be noted though that the wiki is under construction but the switch section is completed and should be accurate (I'm working on it as I can). You may also want to take a look at HHKB Pro 2 Exposed make sure and go to the discussion section as well as that is where the majority of the pictures are. Another good article is Realforce 87U Opened Up it does not have as many pictures as the HHKB Pro article does but you can clearly see how it is put together.

A Topre switch will not work with a membrane because it is a electrostatic capacitive non-contact switch. The domes and springs must be mounted directly onto a PCB for this to work. In all reality the only points of wear on a Topre keyboard are the domes and the key sliders. Topre uses a very high quality rubber for the domes so really no issue there and the same goes for the the key sliders as well. Oh you could also say that the springs could also wear out but again Topre uses high grade materials for those as well. I did not really count the springs because they really contribute very little to the over all feel of a Topre board and the domes take all the stress not the springs.

[AndrewZorn]

it would be a lot easier if the HHKB wasn't priced as if it had MORE keys...

it only their prices were on a per-key basis, not a "ha!  we know what you want..." basis

G11, a 'premium' membrane board: $60 for >103 keys, ~$.50 per key (and base underneath it, "overall size")
Majestouch 104, mechanical board: $130 for 104 keys, $1.25 per key (and base underneath it, "overall size")
Realforce 103, Topre: $2.12 per key (and base underneath it, "overall size")
Realforce 87u, Topre: $2.94 per key (and base underneath it, "overall size")
Happy Hacking, Topre: $4.06 per key (and base underneath it, "overall size")

of course there is more to it than that (electronics, cord), but still...

EDIT and I thought that by "membrane" it was referring to the rubber.  it's a mix of translation and me trying to complicate the translation (and the whole thing in general).

[Rajagra]

I haven't gotten around to melting a Topre key to confirm.  They're too expensive.

Just lend a Topre board to Ram1.

I wonder - maybe the role of the spring has been underestimated. A fully compressed rubber dome can be a bit 'lazy' at popping back up. But the spring doesn't have that problem. It should push the dome away from its squashed position, after which its own springiness will take over. And the less time the rubber spends squashed, the longer it should last.

[joniho]

HHKB Pro HG Japan, Topre: $73.33 per key (~$4400 for this beauty)

http://www.pfu.fujitsu.com/hhkeyboard/hhkbprohg/hg_j.html

[Rajagra]

HHKB Pro HG Japan, Topre: $73.33 per key (~$4400 for this beauty)

http://www.pfu.fujitsu.com/hhkeyboard/hhkbprohg/hg_j.html

Does it really look like that, or have they used a solarising effect on the picture?

In any case, the fancy lacquer they use sounds like what they use on gardening tools out there. :lol:

[rdjack21]

Man I wish people would quit posting that board. I start to drool every time I see it.

[Hak Foo]

it would be a lot easier if the HHKB wasn't priced as if it had MORE keys...

it only their prices were on a per-key basis, not a "ha!  we know what you want..." basis

G11, a 'premium' membrane board: $60 for >103 keys, ~$.50 per key (and base underneath it, "overall size")
Majestouch 104, mechanical board: $130 for 104 keys, $1.25 per key (and base underneath it, "overall size")
Realforce 103, Topre: $2.12 per key (and base underneath it, "overall size")
Realforce 87u, Topre: $2.94 per key (and base underneath it, "overall size")
Happy Hacking, Topre: $4.06 per key (and base underneath it, "overall size")

of course there is more to it than that (electronics, cord), but still...

EDIT and I thought that by "membrane" it was referring to the rubber.  it's a mix of translation and me trying to complicate the translation (and the whole thing in general).

Also consider other non-premium mechanicals:

Unicomp Customizer 104 - $69 for 104 keys = 66.3 cents per key.
Cherry G80 - $65 for 104 keys if you can get it = 62.5 cents per key.
ABS M1 - $45 for 104 keys = 43.3 cents per key.
DSI ASK-6600U - $50 for 104 keys = 48.1 cents per key.

[timw4mail]

Also consider other non-premium mechanicals:
Unicomp Customizer 104 - $69 for 104 keys = 66.3 cents per key.
Cherry G80 - $65 for 104 keys if you can get it = 62.5 cents per key.
ABS M1 - $45 for 104 keys = 43.3 cents per key.
DSI ASK-6600U - $50 for 104 keys = 48.1 cents per key.

Dell AT101W - $15 for 104 keys = 14.4 cents per key
Model  F AT - ~$100 for 84 keys = ~84 cents per key
Scorpius M10 - ~50 for 104 keys = ~48 cents per key

Considering how little these other keyboards cost in comparison, the Topre boards really have an astronomical price.

[quadibloc]

In all reality the only points of wear on a Topre keyboard are the domes and the key sliders. Topre uses a very high quality rubber for the domes so really no issue there and the same goes for the the key sliders as well.

That may be, but I can understand why this would make people nervous.

A rubber dome seems inherently more likely to wear out than a metal spring. The fact that it is the spring, though, and not the rubber dome, that pushes back on the key does mean there is a difference between that design and a membrane keyboard that would attempt to be a good-quality membrane keyboard by using a similar high quality of rubber.

All the rubber dome does is change the key's tactile characteristics.

One could imitate the Topre with a membrane keyboard, then, by adding springs to the keys - and changing the dome design appropriately. Then, the rubber domes would have less work to do, and the difference would be contact switching instead of capacitative switching. But such an imitation would fall short in one important way: even if the spring pushes the key back up, the dome would still have to spring back up by itself (assuming the spring is on the plunger, not inside the dome as in the Topre).

So I suppose an interesting question comes out of this. Were there any spring plus rubber dome keyboards, and were any of them any good, even if not as good as the Topre?