IBM 3278 review (beam springs)

[andrewjoy]

ABS caps can be good , if you use good quality ABS. The ABS in the beamspring is better than 90% of modern PBT caps.

[jacobolus]

micrex22: the switch to PBT was not “upgrading the plastic”. It was switching from double injection molding (expensive) to dye sublimation printing (cheaper).

Most of the changes involved in switching to buckling spring keyboards were related to cutting costs, better supporting internationalization, and abiding by new German DIN standards (e.g. requiring dark gray on light off-gray color scheme, dramatically lowering switch/keycap/overall keyboard height).

The switch to cylindrical keycaps, moving of legends to the corners, switch to a rounded plate with uniform keycap shape, and adoption of dye sublimation printing all went along with needing to print dozens of variants of wacky niche European keyboard legends for every tiny special snowflake country. With double-injection-molded keycaps, such legends are much slower and more complicated to produce. With dye sublimation printing, you can be up and running with all new legends in the blink of an eye.

[seebart]

I presume these are the same "snowflake countries" that "outlawed anything tall or beautiful in the 1980s" in office equipment standards...

[E3E]

ABS caps can be good , if you use good quality ABS. The ABS in the beamspring is better than 90% of modern PBT caps.

ABS can definitely be lovely, but there is a difference in the feel of PBT to ABS, especially when they're textured. PBT has a dry feel that is really satisfying, in my opinion. I do like ABS as well, but it has a "warmer" feel to it. At least for me, it's easy to get the sense that it's a softer plastic because of how it holds texture compared to PBT.

So it's a bit down to preference for those of us that do enjoy PBT more than ABS (he says, while typing on ABS key caps). There is no doubt that the beamsprings' key caps were all very well-made and robust, super thick caps, but the plastic still has the same qualities of ABS, obviously.

That warm feel is actually something I preferred when I first got into the hobby. I was typing on Gateron blank PBT and it felt rough and "cold" to me, while the SA keyset I had recently gotten in felt warm and airy. I loved the feeling.

Right now, I prefer PBT, but ABS is still great, especially when thick.

[andrewjoy]

I prefer PBT too , but to say that the beamspring caps are "cheap ABS" compared to model F/M caps is wrong and thats more my point

[jacobolus]

I presume these are the same "snowflake countries" that "outlawed anything tall or beautiful in the 1980s" in office equipment standards...

Nah, it was just Germany which outlawed tall or beautiful things.

I’m just yanking all your chains here. It obviously makes a lot of sense to switch to a technology that makes it easy to change country-specific legends.

[seebart]

I presume these are the same "snowflake countries" that "outlawed anything tall or beautiful in the 1980s" in office equipment standards...

Nah, it was just Germany which outlawed tall or beautiful things.

I’m just yanking all your chains here. It obviously makes a lot of sense to switch to a technology that makes it easy to change country-specific legends.

Right...so Germany pulled that one single handedly on the rest of the entire world...sure thing. And I mean regardless of whether it makes sense or not I'm still quite sceptical exactly by whom and how that change was implemented! We had this discussion before and I goooogled all this a bit, it wasn't Germany alone, Germany was involved yes.

[micrex22]

micrex22: the switch to PBT was not “upgrading the plastic”. It was switching from double injection molding (expensive) to dye sublimation printing (cheaper).

Most of the changes involved in switching to buckling spring keyboards were related to cutting costs, better supporting internationalization, and abiding by new German DIN standards (e.g. requiring dark gray on light off-gray color scheme, dramatically lowering switch/keycap/overall keyboard height).

The switch to cylindrical keycaps, moving of legends to the corners, switch to a rounded plate with uniform keycap shape, and adoption of dye sublimation printing all went along with needing to print dozens of variants of wacky niche European keyboard legends for every tiny special snowflake country. With double-injection-molded keycaps, such legends are much slower and more complicated to produce. With dye sublimation printing, you can be up and running with all new legends in the blink of an eye.

You're right, there are different grades of ABS, but ABS is still ABS even if it's the highest quality. I prefer a good textured PBT, and it should be considered as an upgrade. In fact, ABS may be too soft and wear-prone to be used for a buckling spring mechanism underneath since it's not merely a simple cap, but also a part of the mechanism itself (not the case with two-piece, but that came later and only for certain key caps).

I think the main reason why doubleshots were omitted on buckling springs is because of the stem. There are no doubleshots that employ a part of the switch mechanism under mechanical stress (to my knowledge). This would be why late selectric IIIs used the same key form factor in doubleshots (or possibly lasered, I've never owned one in the flesh), but not the buckling springs:


Said Selectric IIIs also don't conform to the German DIN standards (with an offering of many 'spicy' colours with black keys), which means the origin of the buckling spring keycap shape was not influenced by it.

We could argue then "well why didn't they re-employ double shots when two-pieces came out", that's because there would still be some single piece keycaps (consistency needs to be maintained) and by that time, Model Ms were sold with the added function of having custom keycaps that could be swapped on the fly. Two-piece keycaps were more expensive to produce*, but presumably this made it easier and cheaper to customize large batches.

*Cost reduction on some M13s reverted back to single piece keycaps


That's my take on it anyways. I think there's a great tendency for everyone to assume 'cost reduced' versus 'practical'. A buckling spring mechanism is more practical because it's more compact, less prone to debris and malfunction, and generates a lot more noise (which was desirable for the time). And we are reminded by practicality with the 'cost increased' options the Model M offered that neither F or Beamspring had. Of course most of that was terminated with Greenock Ms but that came much later

[Chyros]

micrex22: the switch to PBT was not “upgrading the plastic”. It was switching from double injection molding (expensive) to dye sublimation printing (cheaper).

Most of the changes involved in switching to buckling spring keyboards were related to cutting costs, better supporting internationalization, and abiding by new German DIN standards (e.g. requiring dark gray on light off-gray color scheme, dramatically lowering switch/keycap/overall keyboard height).

The switch to cylindrical keycaps, moving of legends to the corners, switch to a rounded plate with uniform keycap shape, and adoption of dye sublimation printing all went along with needing to print dozens of variants of wacky niche European keyboard legends for every tiny special snowflake country. With double-injection-molded keycaps, such legends are much slower and more complicated to produce. With dye sublimation printing, you can be up and running with all new legends in the blink of an eye.

You're right, there are different grades of ABS, but ABS is still ABS even if it's the highest quality. I prefer a good textured PBT, and it should be considered as an upgrade. In fact, ABS may be too soft and wear-prone to be used for a buckling spring mechanism underneath since it's not merely a simple cap, but also a part of the mechanism itself (not the case with two-piece, but that came later and only for certain key caps).

I think the main reason why doubleshots were omitted on buckling springs is because of the stem. There are no doubleshots that employ a part of the switch mechanism under mechanical stress (to my knowledge). This would be why late selectric IIIs used the same key form factor in doubleshots (or possibly lasered, I've never owned one in the flesh), but not the buckling springs:


Said Selectric IIIs also don't conform to the German DIN standards (with an offering of many 'spicy' colours with black keys), which means the origin of the buckling spring keycap shape was not influenced by it.

We could argue then "well why didn't they re-employ double shots when two-pieces came out", that's because there would still be some single piece keycaps (consistency needs to be maintained) and by that time, Model Ms were sold with the added function of having custom keycaps that could be swapped on the fly. Two-piece keycaps were more expensive to produce*, but presumably this made it easier and cheaper to customize large batches.

*Cost reduction on some M13s reverted back to single piece keycaps


That's my take on it anyways. I think there's a great tendency for everyone to assume 'cost reduced' versus 'practical'. A buckling spring mechanism is more practical because it's more compact, less prone to debris and malfunction, and generates a lot more noise (which was desirable for the time). And we are reminded by practicality with the 'cost increased' options the Model M offered that neither F or Beamspring had. Of course most of that was terminated with Greenock Ms but that came much later

I'm not sure PBT is much harder than ABS is. I'd be very surprised if ABS keycaps couldn't stand up to the stress of the buckling spring mechanism.

[micrex22]

I'm not sure PBT is much harder than ABS is. I'd be very surprised if ABS keycaps couldn't stand up to the stress of the buckling spring mechanism.

It has to do with the resilience to mechanical wear, ABS is terrible at it. Eventually the ABS buckling spring key stems would start to hollow out themselves (gradually over time). At least that's what we can assume in theory based on results with ABS plastic in environments where they're in constant physical contact with something.

[y11971alex]

Didn't Greenwich make ABS spacebars? We can check them.

[Chyros]

I'm not sure PBT is much harder than ABS is. I'd be very surprised if ABS keycaps couldn't stand up to the stress of the buckling spring mechanism.

It has to do with the resilience to mechanical wear, ABS is terrible at it. Eventually the ABS buckling spring key stems would start to hollow out themselves (gradually over time). At least that's what we can assume in theory based on results with ABS plastic in environments where they're in constant physical contact with something.

If you're talking about shining up, that has absolutely nothing to do with the hardness of the material at all. It's not your fingers actually rasping away at the keycaps or anything, that'd make it softer than cheese .

[E3E]

I'm not sure PBT is much harder than ABS is. I'd be very surprised if ABS keycaps couldn't stand up to the stress of the buckling spring mechanism.

It has to do with the resilience to mechanical wear, ABS is terrible at it. Eventually the ABS buckling spring key stems would start to hollow out themselves (gradually over time). At least that's what we can assume in theory based on results with ABS plastic in environments where they're in constant physical contact with something.

If you're talking about shining up, that has absolutely nothing to do with the hardness of the material at all. It's not your fingers actually rasping away at the keycaps or anything, that'd make it softer than cheese .

What would you say it is exactly? Why does PBT not shine as easily as ABS but still shine anyway? PBT doesn't seem to react to much, especially compared to ABS. Is there still some component to the oils that cover our skin that messes with PBT plastic? I've always thought that there was a mechanical aspect to shine, more so than any chemical degradation.

[Hypersphere]

Abrasive wear involves the relative hardness of two materials in contact with each other, but this is only one of many mechanisms of wear (e.g., abrasive, adhesive, corrosive, and fatigue). Not all mechanisms are well understood and usually more than one mechanism is operating in real-world scenarios.

Depending on how hardness is measured (e.g., Shore vs. Rockwell), ABS is rated either harder or softer than PBT, but the rating depends on many factors including the presence or absence of flame retardants and/or other materials in the polymer matrix. However, relative hardness is only one aspect of wear.

Regarding the skin-polymer contact that occurs when typing, I suspect (but I do not know) that adhesive wear might be the dominant mechanism. Anecdotally, I have noticed that there is more skin-polymer friction with ABS than with PBT, which should lead to greater wear of ABS relative to PBT.

In addition, with skin-polymer contact, wear is mutual. Our fingertips tend not to wear out because the skin that is sloughed off is continually replaced. I suppose that some of the detritus that accumulates under the keycaps on our keyboards consists of bits of skin and plastic along with sundry other grotesque particles of mysterious origin.

[XMIT]

This would explain why I've seen some worn PBT caps on heavily used Model Fs. It's not that wear doesn't happen, it simply happens at a much slower rate!

[Chyros]

Abrasive wear involves the relative hardness of two materials in contact with each other, but this is only one of many mechanisms of wear (e.g., abrasive, adhesive, corrosive, and fatigue). Not all mechanisms are well understood and usually more than one mechanism is operating in real-world scenarios.

Depending on how hardness is measured (e.g., Shore vs. Rockwell), ABS is rated either harder or softer than PBT, but the rating depends on many factors including the presence or absence of flame retardants and/or other materials in the polymer matrix. However, relative hardness is only one aspect of wear.

Regarding the skin-polymer contact that occurs when typing, I suspect (but I do not know) that adhesive wear might be the dominant mechanism. Anecdotally, I have noticed that there is more skin-polymer friction with ABS than with PBT, which should lead to greater wear of ABS relative to PBT.

In addition, with skin-polymer contact, wear is mutual. Our fingertips tend not to wear out because the skin that is sloughed off is continually replaced. I suppose that some of the detritus that accumulates under the keycaps on our keyboards consists of bits of skin and plastic along with sundry other grotesque particles of mysterious origin.

Tbh I think the main reason ABS wears faster than PBT isn't from pure friction, but from dissolution. I looked this up a long time ago, and found ABS is slightly soluble in apolar compounds, while PBT is more resistant. The caps literally slowly dissolve in your skin oils.

[Hypersphere]

@Chyros: When I first glanced at your post, I thought you said "pure fiction" instead of "pure friction". The former version says it very well!

[Chyros]

@Chyros: When I first glanced at your post, I thought you said "pure fiction" instead of "pure friction". The former version says it very well!

It's the imagination just EATING AWAY at the keycap surface!

[E3E]

Very interesting! Several mechanisms of wear that could potentially be at work. I've never thought of adhesive wear. Literally with skin and oils lifting off tiny traces of the plastic and vise versa?

Dissolution definitely makes sense. I've had ABS key caps that start to show shine after just around two weeks or so of ordinary use, NOS vintage caps for that matter. I'd be very surprised if that was from mechanical wear and abrasion. Adhesion is still an interesting thought, hmmm.

A good test might be to only use a certain untouched set of keycaps while wearing gloves and see how shine develops on the caps. If shine does not develop at the same rate as it has while typing bare-handed, then I'd say we'd have a decent idea that it's something to do with bare skin on the plastic and the oils or whatever else comes along with that.

If it still shined at the same rate then maybe we'd have more proof for adhesion being a big contributor.

[Hypersphere]

Just dip your fingertips in silicone oil before typing. This should allow dissolution to take place, but it should reduce abrasion and adhesion.

[E3E]

Just dip your fingertips in silicone oil before typing. This should allow dissolution to take place, but it should reduce abrasion and adhesion.

I should just pour a bottle of acetone on some doubleshots and then start typing away.

Any idea for what could cause this kind of wear on PBT though? Do we have compounds in the secretions of our skin that can break down the plastic? What would cause adhesion? From what I'm reading, adhesive wear, like galling, is something that that seems to take considerable force. Seems like it's pretty related to abrasive wear as well.

So I would imagine that it's more of a degradation issue.

[andrewjoy]

Wear on PBT keycaps is mechanical wear in my opinion, it does happen after allot of use , i am typing on a 122F with XT caps on now that have been smoothed with extended use, they don't go shiny like ABS does , they do get a slight sheen on them but the surface just gets smoother. Note that it takes decades for PBT to wear , DECADES!

ABS wear has to have something to do with the olis in your skin, i have seen cheap crappy rubber dones shine after about a month of use.

I don't care how crap your plastic is , mechanical wear is not going to happen that fast. ABS is harder than skin, as in the skin will wear off when rubbed against the ABS , skin grows back and will eventually wear plastic down but its not going to happen that fast .

Oils and contaminants reacting with the plastic can happen very quickly, and the different ( cheaper) formula of ABS may react in a different way than the higher quality of ABS we see is something like a beamspring. It depends on additives , processing of the chemicals , differing volumes of Acrylonitrile Butadiene and Styrene who knows.

Without testing we don't know what causes some ABS to shine 100s if not 1000s of times faster than other ABS we would need to do chemical testing to know.

Where is our resident chemist when we need him ?


EDIT

http://omnexus.specialchem.com/polymer- ... ss-shore-d

Shows the hardness of different plastics .

As you can see , raw ABS , with no fire retardants is harder than PBT , ABS with fire retardants is slightly softer than PBT.

This small change in hardness is not going to result in PBT taking decades to wear down and ABS to take less than a month.

Yes ABS with fire resistance is softer than PBT , but not by that much, something much more interesting is going on.

[Scarpia]

ABS wear has to have something to do with the olis in your skin, i have seen cheap crappy rubber dones shine after about a month of use.

I don't care how crap your plastic is , mechanical wear is not going to happen that fast.

(...)

http://omnexus.specialchem.com/polymer- ... ss-shore-d
Shows the hardness of different plastics .

Interesting! And as for the ABS-reacts-with-oils-on-skin theory, I agree. It can't be mechanical wear when we've all had cheap keyboards go shiny after mere weeks of use.

Also, I just want to give a big +1 +1 +1 +1 +1 +1 +1 +1 +1 for backing up your argument with that link. It's refreshing to see commonly held beliefs like "PBT is harder than ABS" (I have read this so often that I never even thought to look it up) challenged AND having the argument backed up by data from a reliable source. That's good scienceing AND good argumentationing!

[davkol]

derp