Abstract: A drafting machine head in accordance with this invention is provided with a rotatable drawing ruler carrier whose angular position on a graduated circle is incrementally detected by means of scanning elements and is converted into displayable angular valves by an up/down counter, and with one or several electronic data stores, characterized in that it contains an electrically actuable locking unit (10, 11) for the rotary movement of the drawing ruler carrier (13), which unit is active in any angular position and is connected through an electronic comparator (25) to the data store or stores (23) in such a way that the valves detected on the graduated circle (12) and the valves contained in the data store (23) trigger the locking if they are in coincidence.By this means a drafting machine head is provided which can be set to a higher degree of accuracy and is less subject to wear than is known from the prior art.