Obviously there are quite a few parts that are unobtanium now.

What is the general opinion on having reproduction parts made? Given that the Curta is quite valuable in original condition, does it make sense to repair an otherwise functional unit with a broken clearing lever? Would replacing it with a *Good Quality* newly manufactured replacement de-value it? Would increasing the availability of "new" parts increase the value of damaged Curtas?

I am looking into options for having new metal replacements made. I have no intention of passing them off as originals and I even came up with a couple minor design tweaks to make them stronger. See below.

Original Top:
https://photos.app.goo.gl/381DU8ty1mk67APP9

New Top:
https://photos.app.goo.gl/tf7HKEPDBqECQ1qX8

Original Side:
https://photos.app.goo.gl/Ehg93RVGZAvtiJQZ8

New Side:
https://photos.app.goo.gl/dFX2VRASmkYitYv29

Original:
https://photos.app.goo.gl/FpAjaAb9e9k5whBW6

New:
https://photos.app.goo.gl/hgLiTSzzUqkJtRYB6

One first place I would mention the usability of a newly repaired Curta. For me the value of a Curta is given by the complete operational state and an overall nice and clean optic.
The monetary value of a Curta will not influenced by replacing a broken part with a non-original duplicate.

I think the clearing lever should be as close to the original as possible - it's not necessary to change the form.

Also important is the fact that you need the fitting rivet (and rivet tool) - and more important, the skills to replace the clearing ring on your Curta!





Good luck with this project...

Thank you for the input!

I agree, the value to me is in a fully functional Curta. The only reason to change the design would be to make the ring more robust and avoid future breakage. I believe the original part is aluminum, and I was going to see if there would be any problem using a different material. If it can be done, the original design may be stronger.

The rivets are not too complicated to make. They are small, but very simple.

I have been looking for information on the original assembly tools and have not found much. There are a few ways it can be done without the original tools.

The only related tool is the "Riveting tool 109.108":



A small spring-loaded tube helps to have the "10.033 - Flat spring" in position during the hit onto the rivet.








Overvew of the four related parts

murff wrote:

The only related tool is the "Riveting tool 109.108": A small spring-loaded tube helps to have the "10.033 - Flat spring" in position during the hit onto the rivet.

That looks about like what I imagined it would be. The punch point for swage is probably 90 degrees or a hair over that I would guess based on the engineering drawings.

Looking at picking a couple of suppliers to do a 2 piece sample run. One will be investment cast, the other CNC machined.

Excellent idea gents. I agree these machines wouldn't be devalued by a fabricated replacement part, "resto-mod" is what we're going for rather than originality. I wouldn't want a nonfunctional machine even if it was a rare one, #40579 lives on my desk and I use it frequently, as the maker intended, that's the charm of them for me too.

Pete wrote:

Excellent idea gents. I agree these machines wouldn't be devalued by a fabricated replacement part, "resto-mod" is what we're going for rather than originality. I wouldn't want a nonfunctional machine even if it was a rare one, #40579 lives on my desk and I use it frequently, as the maker intended, that's the charm of them for me too.

This is going to be a spare time project for me, but I fully intend to get some samples ordered in the next couple weeks.

For material, I have chosen 17-4 as it is easy to machine, strong, inexpensive, and can be PVD coated to get the black color. I have seen PVD coated 17-4 and a color and depth of finish can be attained that is very close to the original anodized aluminum. Because of the material change I am also sticking with the original design/geometry since it will be significantly less prone to breaking.

The second step is to get rivets made, however I am considering an alternative to the swage to attach it to the clearing ring. I need to study the engineering drawings and consider the design before making a decision. Regardless, the rivets are a fairly simple part and I can get them made too.