Abstract: A guiding apparatus in a sewing unit for seaming superimposed layers of cloth having intersecting seams defining areas of increased thickness. The apparatus includes a pair of spaced channel type guides within which the layers of cloth are guided during their advance to the stitch forming instrumentalities. The areas of increased thickness are disposed intermediate the two guides which are both movable to and from positions of close proximity with the stitch forming area. As the guide most remote from the machine's needle approaches the latter the guide adjacent the needle is timed to be withdrawn to an inoperative position permitting the approaching guide to assume the withdrawn guide's operating position thereby permitting the areas of increased thickness to be presented to the stitching instrumentalities without passing through the channels of either of the guides.