Friden S10 gears

[M. S.]

Question: I'm restoring a Friden S10 calculator and I find one of the driving gears called "idler gear assembly" that is worn (see drawing from maintenance manual). Seams like it is made from this material that looks like pertinax. I see it used in other old calculators. this probably was a widely used material.

Anyone can tell me what this material is exactly and if it is still available as raw material (sheet, slate, ...)

Thanks in advance for your help!  

Mirko

[M. S.]

By the way: the photograph in the post is not of the Friden S10, but another calculator. just serves as an example.

Op donderdag 28 september 2023 om 14:29:42 UTC+2 schreef M. S.:

[Laszlo Kery]

Textile bakelite?

[Laszlo Kery]

Or in other words:

Fabric Reinforced Bakelite?

Laszlo Kery a következőt írta (2023. szeptember 29., péntek, 22:53:05 UTC+2):

Textile bakelite?

[M. S.]

I found out that it is indeed phenolic hydroxyl paper or cotton reinforced.

Thanks Lazlo!

BR, Mirko

Op vr 29 sep 2023 om 22:59 schreef Laszlo Kery <keryl...@gmail.com>

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[La Greenall]

When a device has moving parts, one of them is sometimes made to be 'sacrificial' i.e. it wears out so that its opposite number doesn't. The sacrificial part will be either cheap or easy to replace - at least that is during the expected working life of the machine, not half a century or more later!

So if you intend replacing this gearwheel, bear that i mind when choosing the material.

One possible modern material to try might be GRP - [fiber]glass-reinforced plastic. Printed circuit boards are often made of it, so you might be able to order a replacement pre-cut for you from firms such as PCBWay.

For other adding machines (Burroughs) I have had a lot of help from the owners of websites dedicated to them. One even supplied me with a small spare part. So it might be worth you contacting these:

https://www.curiousmarc.com/mechanical/friden-stw-10-mechnical-calculator
https://www.arithmeum.uni-bonn.de/sammlungen/rechnen-einst/objekt.html?tx_arithinventory[object]=21046
https://www.rechnerlexikon.de/artikel/Friden

Lawrence

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[M. S.]

Hi Lawrence,

Thank a lot for the tips and links. Very useful and interesting information indeed! My main and first problem now is getting the gear out to replace it ;-)

BR, Mirko

Op di 3 okt 2023 om 02:02 schreef 'La Greenall' via OldCalculatorForum <oldcalcul...@googlegroups.com>:

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