jrobson: mmm a dwell I don't think so, because what I need is constant axis move instead.
BR549: Yes I am using CV. But the X axis makes a 180° move so it has to stop, so it has to decelerate... and then the A axis decelerates accordingly. Thats the problem. / : The X decelerating is ok because it would give the smooth return for the screw, but the A should go on at continuous feed.