I asked my land lady. She does alterations curtains quilts.well everything! She says she puts a straight edge under the presser foot.(machine off and unplugged!!!) once the edge is lined up where she wants it 1/4 inch she draws a line with a pastel permanent marker all the way across the sewing bed. She says it keeps her from "veering across the field". She talks sewing like she drives a car. "Follow the road child!"