The trimmer includes: a pusher 2 that pushes the bound material 1; a pusher moving device that moves the pusher; a positioning part 111 that positions the bound material pushed by the pusher; an allowable position memory that memorizes an allowable position range relevant to the pusher; an allowable reaction force memory that memorizes an allowable reaction force range relevant to the pusher; and a determiner that determines whether a length of the bound material is normal or abnormal. The determiner determines that: the length L of the bound material is normal; or the length L of the bound material is abnormal.

The trimmer includes: a pusher 2 that pushes the bound material 1; a pusher moving device that moves the pusher; a positioning part 111 that positions the bound material pushed by the pusher; an allowable position memory that memorizes an allowable position range relevant to the pusher; an allowable reaction force memory that memorizes an allowable reaction force range relevant to the pusher; and a determiner that determines whether a length of the bound material is normal or abnormal. The determiner determines that: the length L of the bound material is normal; or the length L of the bound material is abnormal.

A method and a device for trimming printed products on the front edges and/or on the lateral edges. The products are inserted into moved receiving compartments along a closed circuit, the compartments being open on at least one side, and include blades moved along in this region, which act together with stationary counter blades. The depth of insertion of the products is restricted by a support such that the front edges of the products are in the direct vicinity of the open side of the compartments, advantageously protruding with their front edges over the moved along blades for the frontal trimming. The edges of the products extending perpendicular to the folded edge are fixed prior to carrying out a trimming by way of a clamping and moving arrangement and only released for the passing on of the printed product.