I have been shopping for a another CNC for a couple of months now. Trying to compare everything that they advertise as far as components and accuracy. I have spoke to a few companies also. Seems like there is no standard to how different companies measure things. Some have told me that some companies only post the accuracy numbers or repeatability numbers of the best axis. They told me that if the Z axis has +/- .001 but the other axis is not near as accurate then they will advertise it as .001.