Apparatus for cutting patterns from successive contiguous segments of an elongated layup of sheet material has a zoned vacuum table which includes an endless bristle mat conveyor, for shifting a layup along the table to position a segment of the layup in the cutting zone of the table and for holding the layup segment in the cutting zone, and a carriage assembly, which moves a cutting mechanism relative to the table and in cutting engagement with the segment to cut patterns from the segment in response to signals from a programmable controller. A rotary encoder mounted on the carriage assembly has a pinion which engages a rack carried by the conveyor to detect movement of the carriage assembly relative to the conveyor when the carriage assembly returns to its starting position after completing its cutting cycle. A responsive circuit connects the encoder to the conveyor drive motor and energizes the drive motor in response to the relative movement detected by the encoder to cause the conveyor to move the layup in the return direction and through a distance equal to the distance traversed by the carriage assembly in returning to its starting position whereby the next successive segment of the layup is accurately positioned in the cutting zone. An error sensing circuit detects the magnitude and direction of an error in positioning the layup and alters the data in the controller to nullify the error. A vacuum device cleans the bristle mat while the conveyor is in motion and also reduces the vacuum holddown force applied to the layup while it is being shifted by the conveyor.