Topre PBT Spacebars

[Hypersphere]

@cookie: That's a good example of what I meant by saying that the indications and tests people use to differentiate different types of plastics are not conclusive in themselves. If several test and indications are in agreement, the weight of evidence gets better, but still not conclusive.

[chzel]

Perhaps they didn't use bromides (or whatever their name is) for flame-retardants?
Sure looks worn like ABS!

[cookie]

I concider the acetone test as a good method to see if it is ABS or PBT, you can apply a light coat on the underside of the cap to see if it is ABS. This will not harm the cap, even if it is ABS.

[Hypersphere]

I concider the acetone test as a good method to see if it is ABS or PBT, you can apply a light coat on the underside of the cap to see if it is ABS. This will not harm the cap, even if it is ABS.

Did you try this on the spacebar from your HHKB Pro 1?

[cookie]

Because it is well known that the spacebars are made from ABS, I haven't seen the need to try it out.

[Muirium]

There was a Model M with Greek legends on ebay a while ago with a horribly yellowed space bar, though the other keys were all good. Wish I'd saved a picture of it, ebay's useless for preservation.

Anyway, here's another one, which is subtler but still clearly different from the other caps:



Nice worn ABS spacebar you've got on your HHKB 1 there, Cookie! Striking indeed how it hasn't yellowed anything like as much as the case. Try taking it off and shooting pictures against a white sheet of paper and you might find the telltale ABS tan even so. Apparently ABS (like all commercial plastics) is a mixture of things — the S stands for styrofoam, which sounds so cheap! — and I dare say the fire retardant part of the mix was stronger for your HHKB's case. The part which protects all the rest.

[Hypersphere]

Strictly speaking, the "S" in ABS stands for styrene (vinybenzene). Close, however, as "styrofoam" is a closed cell foamed version of polystyrene.

Thus far, searching the net for the chemical composition of IBM spacebars has not yielded definitive answers, but there seems to be some degree of consensus that Model F and M spacebars were, for the most part, made of PBT plastic except perhaps for some of the Model M boards that were produced in Greenock, Scotland sometime in the 1990s.

When I can find the time and materials, I will run some density and acetone tests on spacebars from some of my IBM boards.

[Hypersphere]

Update:

Here is the result of my inquiry today to Unicomp:
-----
Message to Unicomp:

1. What kind of plastic was used in original IBM Model M spacebars? Was it ABS, PBT, or something else?

2. What kind of plastic is used in Unicomp spacebars? Is it ABS, PBT, or something else?

Thank you.

Reply:

Date: 2014-11-04 16:15:02
Name: Customer Service

Message:

IBM and Unicomp use PBT in all keys and spacebars.

Best regards,

Customer Service
-----

[Muirium]

Emphatic!

[matt3o]

we can't do this until later next year. I'll look into other options, but it seems this is not going to happen soon.

[cookie]

I will be happ if it is possible, even next year!
The good think is that all Topre spacebars have a 6 units width, so beside of different collor they don't need different molds for that!

[hasu]

some older topre KBs have PBT spacebars. I think Hasu said his NEWS KB has one.

This is news to me (no pun intended). Did hasu mention this in a thread somewhere or IRC?
As far as I know, the only PBT spacebars on Topre boards are for Japanese layouts.

From test with saturated salt water I can say that space bars from NEWS is not ABS. I saw Realforce(101) and HHKB(both pro and pro2) space bars floated and NEWS ones(both 411A and 5461) sank in the liquid.

You can see HHKB pro and NEWS space bars in this pic.


I can't declare its exact material but I can speculate that NEWS space bar is PBT and Realfoce and HHKB one is ABS from knowledge of keyboard community.

Followings are specific gravity of major plastics and saturated salt water solution has around 1.20.
ABS: 1.05
PS: 1.05
PPE: 1.06
PC: 1.2
PBT: 1.31
PA: 1.14
PPS: 1.34
POM: 1.41

[002]

Great info, hasu!
I'll add it to the wiki this weekend. I'll go through all my other Topre OEM boards and test them too.

[cookie]

Well the Question is, if PFU and Realfoce still claim that they can't produce PBT spacebars because of warping... How does it come that the NEWS spacebar seems to be made of PBT?

I am shocked and irritated!

[Hypersphere]

The other excuse I've seen is color matching, but if you are making both the spacebar and caps with PBT, I don't understand what the issue would be with color matching.

[mSSM]

Update:

Here is the result of my inquiry today to Unicomp:
-----
Message to Unicomp:

1. What kind of plastic was used in original IBM Model M spacebars? Was it ABS, PBT, or something else?

2. What kind of plastic is used in Unicomp spacebars? Is it ABS, PBT, or something else?

Thank you.

Reply:

Date: 2014-11-04 16:15:02
Name: Customer Service

Message:

IBM and Unicomp use PBT in all keys and spacebars.

Best regards,

Customer Service
-----

While that is good and all, I will only start trusting those guys after they deliver on their promise with the SSKs.

[matt3o]

does anyone have a spare topre spacebar even in very bad shape? I need to send it to the manufacturer to check feasibility

[Hypersphere]

I have a black one that I bought as a backup spare from EK. They are currently in stock and sell for $4.50. If the manufacturer is in the USA, it would be cheaper and more straightforward to have one sent to them from EK. I would be willing to pay for this to help serve the cause.

[matt3o]

oh they are pretty cheap, thanks for the headsup I'll take some. The manufacturer is in EU, but MOQ is like 2000-3000 pieces.

Still interested?

[Muirium]

European, and a sky high MOQ? Sounds like our old friends:

Spoiler:

[matt3o]

nope

[Muirium]

What the devil devlin?

[matt3o]

[Hypersphere]

oh they are pretty cheap, thanks for the headsup I'll take some. The manufacturer is in EU, but MOQ is like 2000-3000 pieces.

Still interested?

Yes, still interested. Let me know if you need any help that I would be able to provide.

[matt3o]

okay.

it can be done.

I need to make A LOT of them. Like I said, in the 2500-3000 range and they would cost around €10 each (but they could go as low as €5 based on quantity)

With those figures it would be mandatory the support of some vendors. If there's a real interest I can get this party started.

Important: I need to send one sample to the manufacturer. I can buy some from EK, but it would take time to ship from EK to me and then from me to the manufacturer. Does anyone in EU has one spare to speed things up?

[cookie]

I can send you the one from my pro1, but it has heavy wear:


Will they destroy the spacebar?

[matt3o]

the spacebar wearing is not an issue. they mostly need to see the stems. The spacebar won't be returned, sorry.

If anyone has one spare new spacebar I would get it and return a new one as soon as I get mine from EK.

[cookie]

If mine will do the job, I am willing to send it to you.

[Hypersphere]

@matt3o: You might want to send a recent one to be sure the specs are current. If it would help, I could send one of mine or order from EK and have it shipped to you or the manufacturer. EK is usually quite fast with shipping.

[matt3o]

thanks Hyper, I just wanted to avoid the usual 2 weeks from US to EU. I will be hopefully sending the spacebar to the manufacturer next week