IBM keycap comparison

[y11971alex]

The set on the right is from my Selectric from 1969/70; left, my recently purchased 5251. I decided to take a look at what design features changed during the decade that separated them. Very surprisingly, almost nothing did.

[seebart]

Hmm...good idea. Does not suprise me at all that nothing changed. I still have a Selectric set somewhere.

[Daniel Beardsmore]

Little if anything has changed with Tai-Hao ABS doubleshots between the early 90s and the present day. A rare few things in the world really do remain unchanged. Sadly it doesn't compensate for all the meddling that goes on with everything else.

Now get off my lawn.

[seebart]

Little if anything has changed with Tai-Hao ABS doubleshots between the early 90s and the present day.

Now get off my lawn.

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[y11971alex]

I'm also surprised to find the 5251's caps seems to have come off a newer mould. The Selectric's caps seems to have rounded inner edges.

[seebart]

Right, I'll have a look at mine but I don't know how old they are.

[Ratfink]

Doesn't surprise me either, mostly because I've already looked at beam spring and Selectric keycaps side-by-side in person. But it also doesn't surprise me on principle: if it ain't broke, don't fix it.

[E3E]

Little if anything has changed with Tai-Hao ABS doubleshots between the early 90s and the present day. A rare few things in the world really do remain unchanged. Sadly it doesn't compensate for all the meddling that goes on with everything else.

Now get off my lawn.

It still puzzles me as to why they let go of the Cherry profile caps. I guess that's coming from more of an enthusiast's mind. It probably wasn't profitable compared to their current design.

You can definitely tell that the molds from the old keyboards and the new alps cap sets are practically the same, indeed.

[Daniel Beardsmore]

You mean keycaps that look identical to the ones they make now, but were Cherry profile?

Some of their older keyboards had keycaps that looked like Cherry made them. Now, I know that Cherry were tipped off to cloning at one stage in the past by a company ordering nothing but levelling mechanisms (to be used in conjunction with clone switches) but I seem to recall that these Cherry-like keycaps on Far East keyboards are Alps mount, suggesting that they're not real Cherry even if they look like they are.

[zslane]

Doesn't surprise me either, mostly because I've already looked at beam spring and Selectric keycaps side-by-side in person. But it also doesn't surprise me on principle: if it ain't broke, don't fix it.

Except that for IBM the overriding principle became "make it cheaper", not "if it ain't broke, don't fix it". That's how we got cheap dye-sub cylindricals on buckling springs as replacements for expensive double-shot sphericals on beam springs.

[Mr.Nobody]

Except that for IBM the overriding principle became "make it cheaper", not "if it ain't broke, don't fix it". That's how we got cheap dye-sub cylindricals on buckling springs as replacements for expensive double-shot sphericals on beam springs.

Dyesub on PBT isn't cheaper than Doubleshot on ABS...is it?

[y11971alex]

Several sources in the Toronto Meetup on Feb. 18th told me that these caps are double shot PBT due to the texture of the plastic. Conflicting assessments!

[emdude]

Several sources in the Toronto Meetup on Feb. 18th told me that these caps are double shot PBT due to the texture of the plastic. Conflicting assessments!

I am going to go out on a limb and say that that is a silly statement; ABS key caps that have not been heavily used will obviously retain their original texture and double shot PBT is a modern development in key cap molding (i.e. I cannot think of any vintage keyboard that has been confirmed to use that process). Also, beam spring key caps CAN yellow, like in the photo below.

Spoiler:

[Daniel Beardsmore]

To answer my own question, both:

wiki/File:Tai_Hao_TH-5150-CAT_keycaps.jpg
wiki/File:Newfame3.jpg

So either Cherry were paid to make Alps mount keycaps, or someone replicated Cherry keycaps perfectly:

w/images/7/78/Cherry_G80-3700HAU_--_keycaps.jpg

[y11971alex]

Several sources in the Toronto Meetup on Feb. 18th told me that these caps are double shot PBT due to the texture of the plastic. Conflicting assessments!

I am going to go out on a limb and say that that is a silly statement; ABS key caps that have not been heavily used will obviously retain their original texture and double shot PBT is a modern development in key cap molding (i.e. I cannot think of any vintage keyboard that has been confirmed to use that process). Also, beam spring key caps CAN yellow, like in the photo below.

Spoiler:

I would politely rejoin. First off, the yellowing is not consistent, and the pattern in which the yellowed keys are distributed show no clear correlation with factors that are known to cause yellowing, like UV light exposure. Secondly, the 3101 that I owned (but no longer own) had yellow keys, but they are moulded differently from the keys that remained white:



This is the reverse side of a key that remains white the last time that I saw it.


This is the reverse side of a key that had yellow legends, specifically the "6" key.

[seebart]

I would agree with emdude, although I will say that I am sure we have not solved this question eventough (or exactly because) we have seen so many different examples of keycaps by now. Yes, I also own yellowed Beamspring keycaps. Some of the more interesting older examples were my Cherry M7 keycaps which are quite nice ABS:

keyboards-f2/hal-kb-2100-hal-ct-2100-co ... ?hilit=HAL

I'd have to check my Beamspring and Selectric keycaps to see which are yellowed.

[emdude]

Several sources in the Toronto Meetup on Feb. 18th told me that these caps are double shot PBT due to the texture of the plastic. Conflicting assessments!

I am going to go out on a limb and say that that is a silly statement; ABS key caps that have not been heavily used will obviously retain their original texture and double shot PBT is a modern development in key cap molding (i.e. I cannot think of any vintage keyboard that has been confirmed to use that process). Also, beam spring key caps CAN yellow, like in the photo below.

Spoiler:

I would politely rejoin. First off, the yellowing is not consistent, and the pattern in which the yellowed keys are distributed show no clear correlation with factors that are known to cause yellowing, like UV light exposure.

It's certainly unusual when it happens (I cannot offer any explanation as to why either), but this can be observed in other keyboards. Like with this AT101W for example:

Spoiler:

[y11971alex]

All the yellowed keys are bigger than single size. The only keys that are bigger but unyellowed are the CAPSLOCK and TAB.

[seebart]

All the yellowed keys are bigger than single size. The only keys that are bigger but unyellowed are the CAPSLOCK and TAB.

Yes in that case it's quite "linear", there are plenty of other examples where the yellowing is completely random across the keyboard.

[emdude]

And to that end, I can provide more examples (though for these, the yellowing is not quite as serious):

Northgate Omnikey:

Spoiler:

Apple A9M0330:

Spoiler: