A method of (measuring the waif thickness of an article comprising the steps of (a) providing an inspection machine having an inspection machine co-ordinate system associated therewith, the inspection machine comprising a thickness measuring probe; (b) providing an article in a first position relative to the inspection machine; (c) measuring a plurality of surface points on at least a portion of the surface of the article; (d) modelling the at least a portion of the surface of the article from the measured surface points to produce a surface model; (e) generating a probe path from the surface model in an article coordinate system fixed relative to the article; (f) transforming the probe path to the inspection machine co-ordinate system; and, (g) moving the thickness measuring probe along the probe path whilst making a plurality of spaced apart wall thickness measurements of the article.