Abstract: A plotting head is provided for a slender shaft of consumable marking material, such as pencil lead or graphite, which is capable of producing uniform line intensity at any plotting speed as long as a light stylus pressure is applied to the shaft. The head includes a magazine capable of storing a plurality of such shafts, a feed mechanism for advancing the shaft of marking material as it is consumed during a plotting operation, and an indexing mechanism for rotating the magazine and placing a new shaft of marking material in registration with the feed mechanism each time a shaft is substantially consumed. A torque motor in the feed mechanism maintains a substantially uniform stylus pressure on the shaft when line traces are being drawn and also energizes the indexing mechanism to bring a new shaft of marking material into the plotting position when the old shaft is substantially consumed.