A control system for an apparatus, such as a machine tool (100), for forming a straight configured contour having co-ordinates in at least two directions (X, Y, Z). The apparatus incorporates a workpiece support (102), a contour forming means (107), and incremental drives (M u, M u and M u) to effect relative movement between the support (102) and the contour forming means (107). The components of the straight configured contour in each of the directions (X, Y and Z) are reduced to the number of nominal increments corresponding to a predetermined distance along the contour. A continuous feed of input pulses is provided to a computer for continuous counting in respect of each direction. A drive pulse is fed to a respective incremental drive (M u, M u or M u) to effect movement in the respective direction (X, Y or Z) each time a predetermined number of respective input pulses have been counted, the predetermined number being inversely proportional to the number of nominal increments relevant to the direction. A curviliner contour may be formed from successive straight configured contours.