Abstract: A bookbinding method includes feeding body signatures 2a, from a plurality of body signature feeders 4 disposed in parallel, to conveyor 1 below the body signature feeders 4 and stacking the body signatures 2a on the conveyor 1; obtaining a back-saddle-stitched book a of the body signatures 2a by back-saddle-stitching a back portion of the stacked body signatures 2a from below; spraying paste 9 along a predetermined width on a back surface of the back-saddle-stitched book a; feeding a cover signature 2a from a cover signature feeder 10 to the top of the back-saddle-stitched book a; pressing a back side of the cover signature 2a via pressing apparatus 11 and bonding the cover signature 2a to a back side of the back-saddle-stitched book a; and cutting head, tail and fore edge margins via a three-side trimmer to obtain a saddle-stitched bound book.

Abstract: Apparatus for discriminating signature sets of abnormal total thickness from signature sets having normal total thickness in a saddle-wired preparing apparatus. The discriminating apparatus includes means for electrically detecting the movement of sensor wheels which are adapted to discriminate a signature set of normal thickness from one having abnormal thickness, means for timing the output of this detected signal through a mechanical detector, and solenoid means for switching a stitcher and a deflector lever.