After finishing the second prototype, in the third and final prototype, I was trying to build the metal inner structure more reliable and more fit to the industrial design that I had sketched.
- Bandsaw the aluminum sheet
- sand and polish the edge into the shape desired
- drill holes on sheet for fixing steppers and other mechanism onto it
Soldering, I am becoming master at this eventually. I was using stepper motor easy driver and screw terminals for reliability. Also, I was using hall effect sensor and tiny magnet for calibration. I attached hall effect sensor to the aluminum sheet and magnet onto the time-pulley gear. As a result, each digital has four wires from stepper, three wires from sensor, seven in total, which means, for the whole six digits, it's 7*6 = 42.
In the video below you can see the first working prototype for calibration testing. It started from "B5" board and went back to "B5" after flipping.
I put all the circuit and electrical parts in box. Every time when I open it, either is for debuging it or checking which wire is loose... so I called it as my Pandora's Box.