• Original Odhner Model 27

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My first calculator – the one that started the whole madness. I stumbled upon this one on the 12 July 2020 in the middle of the Covid-19 pandemic in a flea market.


Model: 27

Year: ?

Configuration: 8x13x10

Serial number: 27-257038

Price paid: 110 sek (13 usd)


A typical pinwheel mechanism with a stationary setting up rotor with 10 input digits. The product and multiplier slide has 13 and 8 digits respectiveley. Resetting the product and multiplier is done individually by the cranks on each end of the slide. The buttons on the front are used to move the slide in steps but it can also be decoupled by the lever bellow them and moved freely. The setting rotor can be reset by the brass slide on the left combined with the main crank.

The calculator also has a transfer mechanism which is activated by pressing the button on the right and then turning the product reset crank one turn, resetting the product and transferring the number to the rotor.


Some external damage and a seized-up mechanism. Got it working after a (couple of) complete disassemblies and thorough cleaning. Now works like a charm!

Last Updated on November 5, 2021