There is disclosed a method of controlling, and a control system for, an apparatus, such as a machine tool (100), for forming a straight configured contour, or a straight configured segment forming part of a curvilinear contour, and having co-ordinates in at least two directions (X, Y and Z), said apparatus incorporating a work piece support (102), a contour forming means, such as a milling cutter (107), incremental drives (M.sub.X, M.sub.Y and M.sub.Z) to effect relative movement between said support (102) and said milling cutter (107) in said directions, and involving determining the components of said contour or segment in said directions (X, Y and Z) as a number of increments of length equal to a predetermined distance, providing a continuous feed of input pulses in a computer (S B C), continuously counting in the S B C, in respect of each said direction, a predetermined number of input pulses in the ratio of the inverses of said number of increments, and subsequently feeding via motor control (MCB) and motor drive (MDB) boards,(i) a drive pulse to one of said incremental drives (M.sub.X, M.sub.Y or M.sub.Z) to effect movement in one of said direct directions (X, Y or Z) over said predetermined distance each time the predetermined number of input pulses relevant to that direction have been counted, and(ii) a drive pulse to at least one other of said incremental drives (M.sub.X, M.sub.Y or M.sub.Z) to effect movement in one other of said directions (X, Y or Z) over the same predetermined distance each time the predetermined number of input pulses relevant to that direction have been counted,whereby said movements combine to form a relative movement between said support (102) and said milling cutter (107) such as to produce said contour or said segment.