Abstract: Apparatus to burst form sets from continuous business form assemblies along burst lines, and adjustable to varying form set depths. An intermittently operatively cooperating pair of entry rollers and an intermittently operatively cooperating pair of exit rollers are on a frame. A first of the entry rollers is rotatable about a first axis of rotation and revolvable about a first axis of revolution. A first of the exit rollers is rotatable about a second axis of rotation and revolvable about a second axis of revolution. The revolutions of the entry and exit rollers are timed relative to each other and adjustably timed relative to the speed of the continuous business form assemblies. Both pairs of rollers operatively cooperate substantially simultaneously with each other. Both pairs of rollers operatively cooperate while burst lines of the assemblies are between the entry rollers and the exit rollers.