which implements an overcast stitch sold by porter sewing machine inc of beverly mass other stitchers may be used to join the materials with border tape or with a gusset for example in a preferred embodiment stitcher 80 includes a controller and encoder so that stitches may be counted stitch counting may then used to determine when the top panel is completely joined because stitchers are known in the art they will not be further discussed in a preferred embodiment stitcher 80 receives an electronic signal from controller 200 instructing the stitcher to slow the stitching speed as discussed below stitcher 80 ordinarily receives the materials along a true direction indicated as 34 a 34 the materials are joined along respective edges with known techniques a corner detector 40a is positioned at a fixed distance relative to the needle to detect the presence of a corner of the top panel in a preferred embodiment detector 40a is an ultrasound proximity detector and is fixed to a side of the work surface 11 five inches longitudinally from the needle other detectors may be substituted the detector 40a provides a first indicative signal to the controller upon detecting the corner upon receiving the first indicative signal the controller instructs the stitcher 80 to slow its stitching speed this is.