Today, I made 2 fixtures for the carriage castings including the number dials.
This number dials must not be exchanged because they are different! During the cleaning process in the ultrasonic cleaner, they stay in their original position.

Very cool!

Have you found that debris collects at the bottom of the fixtures, would slots help with flushing debris?

In respect to ultrasonic cleaning; I suspect the dials may be the most sensitive to chemicals. What liquid do you use for cleaning? What has been proven harmful?

I was thinking water with some dish soap and or a touch of vinegar.

@opensourcefan

For cleaning all parts of the Curta's I've serviced so far I use petroleum/kerosene in my ultrasonic cleaner - it gives my the best result.

Cheers
Sebastian

Hi everyone,
Since two years I don't use ultrasonic cleaner on any anodized part of a Curta.
Most of the time it works without problem but it may happen that the anodized part whitens (probably due to the fact of a too thin anodized layer). In such a case it's a disaster.
Now I use ultrasonic only on other parts.
For anodized parts now I do like this : the parts soaked for several hours in distilled water with neutral PH soap, then gently brushed by hand with a toothbrush.
Best regards,
Marc Pellacoeur.

then obviously I rinse.