How the Original Odhner pinwheel calculator works

I'll show and describe how an Odhner pinwheel calculator works. It is an Original Odhner model 24.
For more information about this and other calculators in my collection, please visit my website:
www.jaapsch.net/mechcalc/
0:00 Introduction
0:29 Pinwheel
1:14 Carry mechanism
3:27 Latch
4:26 Input clearing mechanism
7:00 Counter increment mechanism
10:45 Counter carry mechanism
13:34 Back transfer mechanism
15:20 Input display mechanism
16:02 Outro

[@abcstardust]

Thank you for this informative Video!

[@MattDavey68]

Thanks for this. I just baught a model 227 which is very similar to this. I will ber doing a refurb on it very soon.

[@jeffainsworth2696]

Problem with odhner 39 which is very similar to this model revolution counter reset handle jammed and not able to turn it can only be made to work and freed up by replacing zeros with any number on all wheels except the outside two at either end, have tried retiming with no luck any one any ideas please

[@robertlozyniak3661]

I wonder what a machine with this many digits would have been used for. Perhaps calculations involving international banking?

[@jaapsch2]

I'm not sure. As far as I know the main advantage of having this many digits is that you can essentially split the register into two or even three sections that hold separate results from related calculations. For example, if you want to calculate the multiplications 123*456 and 123*789 you can do this in one go by inputting 456000789, multiplying it by 123, and reading off the answer in two 6-digit sections.

[@EmmanuelCoirier]

The uppers teeth on the wheels are indeed used by the input register display that is missing here, as you thought. They engage with the pins on the right side of each digit roll. The digits rolls are the same for the three registers : they all have a pin on the left of the roll for the carry, even if this pin is of no use for the input register, which never travels from 9 to 0 or 0 to 9.

[@jaapsch2]

@@EmmanuelCoirier Thank you for confirming this!

[@19ghost73]

Useful also if You do want to calculate with high precision fractions, i.e. results with many digits right of the decimal point.

[@GeriIndustrialDesignerPrivate]

ibm