Author Topic: One off of my Bucket List - Trommelwähler  (Read 534 times)

Offline Jim Stettler

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Re: One off of my Bucket List - Trommelwähler
« Reply #15 on: November 21, 2019, 05:56:40 PM »
didn't WE try this design? I faintly remember a 302 that was looking like that.
There was a 1940 concept set shown on Paul F's prototype page
http://www.paul-f.com/weproto.html
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Offline paul-f

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Re: One off of my Bucket List - Trommelwähler
« Reply #16 on: November 21, 2019, 07:00:49 PM »
didn't WE try this design? I faintly remember a 302 that was looking like that.

Perhaps you were thinking of this one...

http://www.paul-f.com/weproto.html#CylinderDial
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Online Jack Ryan

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Re: One off of my Bucket List - Trommelwähler
« Reply #17 on: November 21, 2019, 07:16:16 PM »
Can you clarify the materials used to make the cases of these telephones?

The 261 Trommelwähler was made from '52 on and in black or ivory duroplast (bakelite/melamin).

As I understand it, the black 261 was made of Bakelite (Phenol Formaldehyde) and the Ivory of Melamine (Melamine Formaldehyde).


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The 264 appeared in '54 and was also available in red and green. These colored models are extremely rare.

These were made from polystyrene.


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All these models never were issued by the Bundestpost (phone co.) but only available for PBX.

They were not used by the Bundespost but someone used them (possibly) other than on a PBX. There is a model with no button and one with two buttons.

Jack


Offline countryman

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Re: One off of my Bucket List - Trommelwähler
« Reply #18 on: November 22, 2019, 02:49:22 AM »
That sums it up pretty good I think.
Quote
These were made from polystyrene.
My observations accord with that. The way my 264 case broke does not look typical for ABS. It seems the material is somewhat more brittle, like polystyrene is. ABS may have been available when the case was made but not yet in common use as a material for phones.

I also agree with Tubaman's observation that the case is really thin and fragile. Interesting to see that WE prototype - I'm pretty sure the system would have caught on sooner or later, if touch tone had not happened...

Edit to add, in Dietrich Arbenz' book I now found confirmed the Fg tist 264 shell is from polystyrene. ABS was used from the 1960ies on by Siemens. For a possible repair I think this will not make a huge difference, besides using the appropriate material to produce a putty?
« Last Edit: November 22, 2019, 03:40:14 AM by countryman »

Online Jack Ryan

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Re: One off of my Bucket List - Trommelwähler
« Reply #19 on: November 22, 2019, 03:13:42 AM »
That sums it up pretty good I think.

Thanks for that.

Jack

Offline countryman

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Re: One off of my Bucket List - Trommelwähler
« Reply #20 on: December 01, 2019, 07:36:35 AM »
I now finished the repair. It did not come out perfect, but I like the result for a daily driver.
I made a putty by dissolving parts of a spindle where blank CDs came on, using acetone. After some trials on junk parts I closed the hole with this putty. It hardened well, but formed tiny bubbles, and the color is not true black any more, like the parts were before melting them. Useing Milliput might have been a better choice? It is available here on the continent from specialized modeling shops. I have not found any other epoxy that comes in black.
I'll not repair the microphone cap for now, but found a replacement from a military handset of the same period. It needed a little milling on the inside to remove some material - the donor handset (last picture) has a deeper recess for the mic. capsule.

Offline HarrySmith

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Re: One off of my Bucket List - Trommelwähler
« Reply #21 on: December 03, 2019, 09:03:57 AM »
Try some black shoe polish. It should help with getting it more black & also more gloss.
Harry Smith
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TCI

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there is only
do or do not"