I am interested in tightly spooling the wire on a coil former. The coil will then be used for another project and it has to be well packed. Instead of working form the theorical diameter of the wire when making the coil, I am interested in measuring it as it unwinds from it's original spool (more accurate).
So you're trying to wind inductors? Are these audio inductors?
I'm just thinking, who cares about the EXACT diameter of your wire (and whatever 0.01mm variations it has)... it's more important to get the correct inductance and DCR (within % tolerance) of your limited equipment? .... rather than worrying about it's diameter?
Maybe build an inductance meter using an Arduino (very possible, with high accuracy) and have your machine keep winding until the set inductance value is reached -- regardless of your wire diameter variations.