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mwu
Joined: 05 May 2015
Posts: 39
Location: SC, USA
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 Posted: Sun Jun 16, 2024 12:56 pm Post subject: |
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| Ravlen wrote: | Oh, I should have posted this first, but I was able to extract the last bit of broken pin from the shaft, which is why I was able to work on other things finally.
 
I found the correct size hollow pin to fit in there, but I was not able to get any to fit all the way in correctly (without bending). I tried a solid pin and that worked fine, so I'm using that for now. |
I took the bottom off of my Type II and took a look at the pin because the Type I uses a roll pin instead of a solid or hollow pin. I verified that at least in mine, the pin you reference is in fact a roll pin in my Type II. Based on the engineering drawings, the hole should be around 1x6mm. Something like this: https://www.mcmaster.com/91611A067/ |
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Ravlen
Joined: 11 Feb 2024
Posts: 15
Location: Japan
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| Posted: Tue Jun 18, 2024 2:25 pm Post subject: |
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Some additional information. I contacted Romano (someone shared their email in another thread, but I believe they run http://www.curtaservice.it/?) and asked if they had any advice, and shared this with me (and said it was OK to share on the forum):
| Quote: | I figured out what the problem is.
It must have been caused either by a fall or by somebody forcing the curta, which altered the correct alignment between zero positioning disc, step drum and tens unit (which also cut off the step drum pin). Now, if what you mention is the only issue your curta has, that is if it calculates correctly both in addition and in subtraction mode, without any carry error and without getting stuck, the problem can easily be solved.
What you have to do is reassemble the curta without the lock pin and grind a lot in addition and subtraction mode, slowly and fast. If everything goes smoothly, you can use a suitable file to smooth out the small part of the lock disc that protrudes into the lock pin hole in zero position.
If the curta, instead, has other problems or doesn’t calculate correctly, then you’ll have to correct the misalignment from the zero positioning disc to the lock disc trying to understand what got bent (pins or other). |
So my plan is to reassemble and double check the functioning as best I can, without the carriage lock pin. If there are other issues, I'll work on those first, before resorting to filing down the locking disc if necessary. I could already tell that at least 2 carry levers were not working perfectly on the first assembly, so there's definitely work to be done first. |
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Ravlen
Joined: 11 Feb 2024
Posts: 15
Location: Japan
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| Posted: Tue Jun 18, 2024 2:30 pm Post subject: |
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| mwu wrote: |
I took the bottom off of my Type II and took a look at the pin because the Type I uses a roll pin instead of a solid or hollow pin. I verified that at least in mine, the pin you reference is in fact a roll pin in my Type II. Based on the engineering drawings, the hole should be around 1x6mm. Something like this: https://www.mcmaster.com/91611A067/ |
Oh, thanks a lot! I found that type of pin online (in Japan, where I'm located), but could not find the correct dimensions! I'll have to see if they deliver internationally, or perhaps to one of my coworkers in the US. I did think it could be a pin issue, though the fit is sooo tight I found it hard to believe I could have inserted a solid pin without aligning it perfectly... but now I'm starting to doubt myself. I shall have to replace the pin and double check that as well, thanks!
I do have solid pins, but I also have some split pins used for watch bands that might work as well, so I've got plenty of things to try before I pull out the metal file and permanently alter the locking disc... |
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