Guys, i will not post more here, as it seems its for another thread. But i think you are right. There is something wrong maybe i have wired things especially the grounding and shielding. As a ground wire from here to there changes the spindle speed. I am not mixing VDC and AC and Earth. When i say ground i mean the shield that goes to common earth , where all PSU earth wires are connected together. I think the VFD and the servo drives mess things up. It could be as the VFD to spindle shield is wired both sides, one side to line ground, other side to spindle and machine body.