JPH0380B

A sewing machine for making a threefold hem in each of the legs of a pair of trousers has a folding guide member for turning a bottom edge of the trouser leg inwardly of the trouser leg, a revolving roller positioned below the folding guide member for rocking motion in a direction rightwards and leftwards, and a detecting plate positioned above the folding guide member for the detection of the passage of at least one seam in the trouser legs over the folding guide member and movable up and down. When the bottom edge of each trouser leg having been folded to provide a double-layered bottom edge has been set on the machine and circumferentially stretched by the revolving roller, an inner fold of the double-layered bottom edge of the trouser leg is scooped up and folded inwardly by the folding guide to form a threefold hem and, during the continued revolution of the trouser leg in a direction circumferentially thereof by the action of the revolving roller, the detecting plate can detect the passage of the seam in the trouser leg, permitting the machine to initiate a stitching operation from a predetermined position preceding a sewing needle. After one complete revolution of the trouser leg and upon the detection of the passage of the seam by the detecting plate, the machine can terminate the stitching operation at a location which has passed a predetermined distance beyond the starting position.