This project was about three years in the making.  The first attempt to open the old safe involved a stethoscope, progressed onto using Lego Mindstorms and finally was successful with the stepper/encoder configuration shown here.

The link 'History and details of auto dialer' has slides, video and text explaining how these safe combination locks work, details of the two auto dialers built and a full explanation of the core of the Python code written.