Abstract: Slitter knives on a paper winder are moved to new positions by a bar to which the knife supports are coupled by means of a pin, carried on each support, and which engages in one of a number of holes equi-spaced along the bar. The bar is reciprocated so that the supports may be moved, in either direction, by successive increments equal to the hole pitch. The supports are moved in this manner until they each reach the nearest and most expedient hole to the new position. The bar is then moved one more pitch and as each support is determined to be at its new position its pin is withdrawn from the hole and it is clamped to stationary rails.Mounted on the bar opposite each hole is a switch arranged for operation by the pin, and connected to a central micro-processor which continuously monitors and controls movement of the knife supports.