...Based on a reference points (which are included in PCB production files during DIY manufacture) it is possible to layout different PCB layers during drilling, UV exposing, gluing &final cut. Each time PCB was dismounted from a CNC and mounted again, it will have some angle of rotation over a zero point (X=0, Y=0).
Manual measurement of this rotation angle is performed with help of laser module mounted on the same CNC. For each reference point, travel CNC with a laser module and fine tune X/Y coordinates to target at the center of a drilled point (laser light will dim out). ...