Abstract: Apparatus and method for fluid jet cutting of a roll of material in situ, e.g. a multiplicate wound roll of material, by which a fluid jet nozzle and a roll of material are rotated relatively to each other about an axis with the roll of material in radially inwardly disposed relation to the nozzle while a fluid jet, e.g. liquid jet, exiting from the nozzle is directed at a selective axial point along the extent of the roll of material to cut circumferentially into and through the roll of material in situ and the spent fluid is concomitantly collected radially inwardly of the roll of material, preferably in an arrangement having fluid jet cutter means including such nozzle, support means including mandrel means, e.g.