greywulf - once you encounter a left homing machine, you'll understand. It is physically impossible to sew a straight stitch with the needle anywhere other than the far left position. If you can sew a straight stitch in the left, center and right, then you have a center homing machine. Most vintage zig zag machines only have those three setting for straight stitch. With my main sewing machine, I have center, 6 positions to the left and 6 to the right. When I set it to 4 right, I get a nice 1/4 seam when lining the fabric up with the edge of my regular foot.