Many parameters influence the positioning errors of machine tools. Amongst them are the link geometric errors that describe the relative location between the machine's successive rotary and prismatic joints and, the motion errors, describing the non-ideal motion of a joint. A method is proposed that uses a telescoping magnetic ball-bar to indirectly calibrate these errors on a five-axis machine tool. The motion error sources are individually modelled as polynomial functions of each joint coordinates. This modelling method conveniently incorporates the link geometric errors. Once the polynomial coefficients are identified, it is then possible to predict the tool versus workplace position and orientation errors resulting from these error sources.