Keep your Z-axis motors synchronised with this adjustable indicator.
The Anet 3d printers are equipped with two motors for the Z-axis movement that can easily loses position of each other.
With this indicator installed on each Z-axis motor you can accurate keep the wright alignment.
After installation, align your printer and move to zero Z position.
Use a pointy marker pen to draw a line between the pointers on the flexible couplings.
From now one the correct position can be checked on this zero Z position and any +8MM Z position.
If the motors have lost the synchronization, turn off the printer and rotate one of the couplings so that the markings realign.
For any later marking position adjustments, the position of the indicators can be adjusted or the markerline removed with some alcohol and redrawn.
4x M3x16 bolts and M3 washers are needed to mount two indicators.
The indicator was printed with a 0.2 layer height setting, 100% infill and PETG filament was used.