The Curta.org Bulletin Board

[answerguru]

Hello!

So after years of searching, I finally purchased one of my dream objects, a Curta. Everything below is written as a relative Curta novice, although I've read a lot, have been an engineer for 30 years, part of which was work on very complex biomedical robotics and MRI systems. I'm not afraid to take anything apart and put it back together. Hopefully with no extra screws optimized out!

This Type II was found by a friend at a pawn shop and they were asking $800. I drove up there and on visual inspection it looked quite nice, with not a ton of wear. It included the metal case and a leather holder. However when I ran some of the test calculations, I noticed that not everything was in working and there was a loose part inside. Yikes! It did perform most calculations properly, but the last output digit would often roll to a 9 for no reason.

I used what I found to negotiate with the owner and finally was able to walk out with it for $400 USD. I have recently taken the bottom and shell off, just to do some inspection. The loose part was the brass bottom of one of the input shafts, which I slipped back into place. Here's what I have found:

Input digit sliders are sticky, hence a general service
Bottom plate is missing one of the 2 long screws
Cam preventing reverse cranking has come off. The screw holding the cam has sheared off and the spring may not be correct.
One of the small plates that hold the bottom of the input sliders in place is missing. I have added a small piece of tape to hold the brass ends in place.
The last output digit sometimes shows a 9, when it should be a 0 after an operation. The two gears on top of the shaft for that digit don't seem to stay positioned properly.
The crank will occasionally get stuck during a revolution.

Here is a link to some photos:

https://drive.google.com/drive/folders/1--OtuCovbL9EGLHtemwGq4xT1pHjG3Ms?usp=sharing

Just today I have emailed three places for possible repair discussions:
Curta Service in Switzerland, Bernd Schroeder in Germany, and Marc Pellacoeur in France. The website for the Italian repair guy is no longer operational.

Any expert opinions, thoughts, and rants are welcome!

Thanks,
Jonny

[murff]

Roman's website works perfectly:

International Curta Repair

(Avoid the Curta service in Switzerland - why? ...read the forum)

[answerguru]

It looks like it works perfectly on mobile, but on 2 different browsers on my laptop there is an SSL mismatch and is blocked (even if I add an exception for the site).

Anyway, thanks! I will email Roman.

[RAPA]

Romano is operational, I had a Type II inspected a few weeks ago.

And he usually responds right away.

romano.manaresi@fastwebnet.it

[answerguru]

RAPA wrote:

Romano is operational, I had a Type II inspected a few weeks ago. And he usually responds right away. romano.manaresi@fastwebnet.it

Thanks! I appreciate the info.

I'm going to forward my original request to this email just in case.

[Ravlen]

For IMG_6789.jpg, it looks like the carry lever is bent out of shape (which I think could happen easily if the anti-reversing pawl (IMG_6788.jpg) had fallen off and someone tried to crank it backwards.

[answerguru]

Ravlen wrote:

For IMG_6789.jpg, it looks like the carry lever is bent out of shape (which I think could happen easily if the anti-reversing pawl (IMG_6788.jpg) had fallen off and someone tried to crank it backwards.

Ahhh, good eye! I do know that the anti-reversing pawl was broken / dislodged - actually the pawl spring was not engaged and the screw had sheared off.

I just got word from Romano that everything has been repaired / upgraded and it was just shipped back from Italy to the US. Can't wait to see it fully functional and restored!