Disclosed is a timber-working head (500) including a frame, a first arm (301) and a second arm (302) such that the first (301) and second (302) arms are pivotally connected to the frame. A first linear drive actuator is connected to the first arm (301) and a second linear drive actuator is connected to the second arm (302). The linear actuators are configured to pivot the respective arms (301, 302) relative to the frame to open and close them. At least one processor controls application of pressure by the first and second linear drive actuators such that the arms (301, 302) grasp timber to be processed by the head (500). The processor then determines whether the position of the linear actuators indicates that the timber is offset from a feed axis (502) of the frame beyond a predetermined distance. Finally, the processor controls application of pressure by either the first linear actuator or the second linear actuator to reduce the offset to be within the predetermined distance.
