Hi guys,
the steel part that the indicator touching was the spindle head(a machined bulky steel cube which i mount the BT40 spindle) its outer face may or may not be perpendicular with the indicator, the indicator is parallel with the moving axis since the touching point is a sphere the surface will always stay tangent to it so the indicator will only show the moved distance. There is no that much machining error on that touching surface in reality its mostly the camera's optics doing the distortion.
For me,
to get this kind of readings in linear movements and machined squares and rectangles being 10-20micron accurate is weird,
machined squares and rectangles being 20micron accurate but circles being like an ellipse in 30-60 degrees to both X and Y +60microns is weird,
sometimes getting 1-2micron positioning accuracy and mostly get 30-50micron positioning error in every axis during the measurements is weird,
in full 1 turn reading the actual pitch and in small increments reading this error is weird,
getting this positioning error in small movements and seeing that every axis return to zero after moving 500mm within couple of microns is weird,
At first i also thought that this looks like an mechanical error thats why i took apart the moving components(motors, ballscrew supports, ballscrews, nuts, couplings, etc) and realigned/fixed them all over again. Linear rails in every axis are schneeberger and aligned/paralleled within 15microns, of course there is an error in every guideway when u move the axis but it does not result a total error more than 10-15microns(in high speed movements).
But there are things which proves that this is not mechanical error(other than being checked all of the mechanical aspects), mechanical error should always be there and should be repeating. If it was ballscrews it would add with the distance moved but its not adding, it reaches to 50-60micron error in 10mm and stops, it does not add more to it.
i was sure that this is because of the pulse signal loss and differential drive gonna fix it when Russ suggested that but seeing the actual pulse reaching the driver and drivers performing the commanded pulse without loosing even 1 digit in 10000 pulse per revolution made me more confused.
Regards,
Hakan