Abstract: A method of calibrating a scanning system comprising a machine and a measuring probe, includes the steps of error mapping the system statically and qualifying the stylus tip so that the system will provide accurate measurements, determining the positions of a number of datum points on the surface of an artefact with the probe stylus in contact with the workpiece and at zero deflection normal to the surface, scanning the surface through the datum points at a nominal stylus deflection and at the maximum speed which provides repeatable position measurements to make a second determination of the positions of the datum points, determining the errors attributable to the scanning process by subtracting the positions obtained in the first and second determinations, and storing the error values for correction of subsequent measurements of similar artefacts.