An apparatus for capping a stem web including a cooled roll, a first heated nip roll positioned to form a first nip with the cooled roll, and a second heated nip roll positioned to form a second nip with the cooled roll. The cooled roll has a diameter that is at least 30% larger than a diameter of the first or second heated nip roll. In an embodiment, the two nips are on opposite sides of a larger central cooled roll positioned between the heated rolls. In an embodiment, the reaction forces between the rolls are measured and controlled at each end of each of the heated rolls. The invention is particularly adapted to making abrasive particles that are attached to a driving mechanism via headed stem fasteners formed by the method.