I looking at the feasibility into designing a mechanical clock driven by a stepper motor with no escapement as I'm after a true sweeping second hand. I would like to be able to correct the time with something like this - Ultra-precise Real Time Clock - v2.1 ( ChronoDot - Ultra-precise Real Time Clock [v3] : ID 255 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits ). I'm wondering what would be the best way to get feedback from the clock works to tell the arduino the time on the works.
If you have the conventional coaxial connection to the 3 hands, you could selectively make them reflective at different distances from the center, have 3 sensors, and be able to detect the 12:00:00 condition. Drive to that and then assume your stepper won't miss steps to set the time.
At least it would be impressive while setting the time. Kind of like a cheap movie: "Time Passes"....
Thanks for the replies, yes it will be driven off one stepper, I might even add an idler gear off the main hour hand gear to detect position. Terry I had a look on your site, I do like the look of the light beam sensor, all I would need to do is mill a slot in the idler gear.