The Curta.org Bulletin Board

[Axel]

Hello,
My name is Axel, I live in France, and two months ago I bought a type 2 Curta calculator (SN 500713).
This machine had a problem, it increased numbers on the results even when all the selectors were on the "zero" position...
So I disassembled it entirely, and noticed that the interior was completely stuck by oxidation.
All the carry levers were bent, nine carry levers springs were out of service, and one transmission shaft circlip was broken...
This Curta is in perfect condition on every other regards ! So I decided to manufacture all broken parts...
First I made a tool which permits the fabrication of circlips, and now I imagine a making method for the ten carry springs.
I'll post photos as soon as it's done !

I'm looking for any information about small numbers Curta II, schematic, repair manual, etc...

Greetings from France !

Axel

(Sorry, I didn't find how to join photos with my post...)[/url]

[Ravlen]

Hey, I'd love to hear about your project. This is very similar to my own Curta type II repair project, see https://curta.org/phpBB2/viewtopic.php?t=779

I'd love to see how you fabricated the circlips. I managed to create carry lever springs by hand, but have not figured out a good way to do the circlips. I broke one during maintenance, and would love to make multiple spares.

For sharing pics here, I've used https://imgbb.com/

[Axel]

Hello Ravlen, and thanks for your response.
This evening I'll try to post photos about my homemade circlip fabrication, based on the link you sent.
Have a very nice day !

Axel

[Kmcqueen]

Lots of information and scanned manuals etc. here........

https://curta.li/05_anleitungen/index.php

(in general this website has tons of great info and pictures!!!!
https://curta.li

[Axel]

Hello, here are photos about circlips fabrication.
I started with an old watch main spring...
https://ibb.co/ScmQKRk
https://ibb.co/G2S0jY3
https://ibb.co/ZNYDPJw
https://ibb.co/SQg5vL1

[Axel]

[Ravlen]

Oh, thanks a lot for the pics, that's an interesting way to do it!

I had actually considered buying a watch spring for this, but I couldn't figure out the exact dimensions of the watch springs for sale online. The numbers didn't seem to show the actual width/thickness. For example, I found things like this: https://www.amazon.co.jp/-/en/dp/B0CQBBQFDC, but have no idea what size ETA 2824-2 or ETA 2836-2 would be...

Do you know the right type of spring I should look for?

I'll try to make a video to show you how I do the carry springs with small pliers. It doesn't seem very precise, but surprisingly the majority have seemed to turn out accurate enough.

[Axel]

Hello Ravlen, the spring must be 1 mm width, and around 0.10 mm thickness.
For example you can follow the link below, or maybe contact a Japanese watches parts provider.
You will have to heat the piece of string to dark red, and remove it very slowly from the fire. So you could work on it, and after correctly shaped you'll have to heat it again to dark red (but not directly on the flame : circlip layed on a metal sheet), and drop it in oil until cold.
I do like that, and it works correctly..


https://ressortdebarillet.ch/collections/ressorts-de-barillet-swiss-made-recherche-par-hauteur/products/1-00-x-12-x-305-x-9-00-mecanique