ABS-cased Model M keyboards?

[Sheepless]

I've recently added another Model M to my collection. This one is a battleship from June 1986 (model 1389160). It has the F122-style upper case, with those ridiculous two-part legs, so I'm quite pleased with it, though it's badly in need of a bolt mod.

Anyway, what surprises me is that the case is badly yellowed, even after cleaning. I'm guessing that, unlike my other Model Ms, it's ABS (though there's no obvious material mark inside the case). I've read that the Greenock plant, at least, produced some ABS cases. Does anyone know how common these are?

I don't intend to retrobright it. Like me, it shows honest signs of old age, and I'm content to let it stand out from its beige younger siblings.

[Muirium]

That's a good attitude! It's not your only M and this imperfection lends it character.

IBM Greenock was definitely up to dodgy stuff. Hopefully with permission from above! ABS just wasn't IBM's style, but there's no denying it's era appropriate in general.

[Lynx_Carpathica]

I want pics of it.

[Sheepless]

That's a good attitude! It's not your only M and this imperfection lends it character.

IBM Greenock was definitely up to dodgy stuff. Hopefully with permission from above! ABS just wasn't IBM's style, but there's no denying it's era appropriate in general.

Thanks. Greenock certainly used ABS for some space bars, at least, because I have a couple. It's funny when the rest of the keys look good as new, being PBT, while the space bar is the colour of cheddar.

[Sheepless]

I want pics of it.

Sorry, can't at the moment, because it's in storage until I have time to mod it. I have very little space at home, so I have to be ruthless about moving stuff out to storage when it's not needed.

[Crizender]

I have an Italian M122 Gen 2 from Greenock that has yellowed, from what I understand they sometimes used ABS instead of the usual PVC. Overall its pretty uncommon to see, but cool nonetheless. I believe a few people in the Model M discord also have ABS ones.

[jsheradin]

Generally speaking, you need to design injection molding equipment for a specific type of plastic due to various flows, shrinkages, etc. A mold of this size for PVC probably couldn't be used with ABS and vice versa.

In case the dates are relevant, I have a Greenock M122 (1394167) made 15-08-96 with a PVC case and ABS spacebar. There's a mold tag that pretty clearly indicates PVC.

I wonder if IBM US' PVC molds/inventory were split up between Lexmark and Greenock when everything shifted.

Spoiler:

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[Sheepless]

I have an Italian M122 Gen 2 from Greenock that has yellowed, from what I understand they sometimes used ABS instead of the usual PVC. Overall its pretty uncommon to see, but cool nonetheless. I believe a few people in the Model M discord also have ABS ones.

Do you know the manufacture date of your M122? And are there any identifying marks inside the case?

[Sheepless]

Generally speaking, you need to design injection molding equipment for a specific type of plastic due to various flows, shrinkages, etc. A mold of this size for PVC probably couldn't be used with ABS and vice versa.

In case the dates are relevant, I have a Greenock M122 (1394167) made 15-08-96 with a PVC case and ABS spacebar. There's a mold tag that pretty clearly indicates PVC.

I wonder if IBM US' PVC molds/inventory were split up between Lexmark and Greenock when everything shifted.

Spoiler:

Capture.PNG

My Greenock M122 with the ABS space bar and PVC case is from August 1990, and has the grounding wire for the space bar.

[Crizender]

I have an Italian M122 Gen 2 from Greenock that has yellowed, from what I understand they sometimes used ABS instead of the usual PVC. Overall its pretty uncommon to see, but cool nonetheless. I believe a few people in the Model M discord also have ABS ones.

Do you know the manufacture date of your M122? And are there any identifying marks inside the case?

Its 09/09/1986. I've got it stored away at the moment so I can't have a look inside of it yet, however I don't believe there was anything Identifiable that would signify a difference between PVC and ABS.

[Sheepless]

I have an Italian M122 Gen 2 from Greenock that has yellowed, from what I understand they sometimes used ABS instead of the usual PVC. Overall its pretty uncommon to see, but cool nonetheless. I believe a few people in the Model M discord also have ABS ones.

Do you know the manufacture date of your M122? And are there any identifying marks inside the case?

Its 09/09/1986. I've got it stored away at the moment so I can't have a look inside of it yet, however I don't believe there was anything Identifiable that would signify a difference between PVC and ABS.

Thanks. So it sounds like something was afoot at Greenock in 1986. The part number of my top case is 1387194, and other marks inside say 4759, DN3255, and a date wheel showing April 86, a couple of months before the date on the back label.

Incidentally, while the upper case is similar to that of my F122, it shows signs of cost-cutting compared to the model F, lacking the brass inserts the F has in the screw holes. As much as I like model M keyboards, even from their early days they were on a downward trajectory compared to the F.