Refer to the following link to see images: https://www.in.tum.de/rbg/mediendienste/referenzprojekte/abakus-uhr/geschichte/bilder-der-herstellung.html
The principle is very simple. The spheres above the wooden board are worth 5 each and the spheres below are worth 1. This allows us to display every the time in the 24h clock-style.
I will split the project into two parts. The first part will be about rebuilding the clock with LEDs and in the following part we will add some more LEDs to display the seconds as well.