This evening I'm cleaning, repairing and refurbishing a Comptometer model 3D11 from the 1950s. This was the last Comptometer the company made and has its final speed and accuracy improvements before the world moved to electronic calculators.

So I made some progress with refurbishing the Comptometer this weekend. I freed up many stuck registers, but that revealed an issue with the carry mechanism on a few digits I will have to investigate further.

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@sbeebe The register is in the front of the device lined up with each column of keys. In the picture everything is currently blank but once you depress a key it would add to the corresponding register. I demo a similar (but a few decades older) Comptometer in this thread.

social.librem.one/@kyle/107113

Once I finish cleaning and repairing this one I'll follow up with a thread demoing and explaining it.

@kyle Fantastic! Thank you for sharing. What a cool machine. It seems like they are peak mechanical prowess.

@sbeebe Yes I would say that Comptometer and the Curta are great examples of peak mechanical calculators, with a Marchant Silent Speed being another if you include electrically-driven ones.

@kyle impressive, so much mechanical complexity at glance, seeing that many components together is a lot more entertaining than a circuit board.

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