A general quality assurance system to perform in-process inspection through on-line monitoring is proposed in this paper. Technical issues related to the model based indirect measuring approach to retrace the quality control target are discussed. This research analyzes the dynamic characteristics of dimensioning and geometric tolerancing through surface topography generation through incorporation of random tool motion analysis in the evaluation of machining accuracy. Statistical methods for estimating metrological indices, such as roundness and straightness, have been developed to assist in the determination of control limits designed for on-line detection of disturbances external to the normal machining process.