yep the cutting surface matters.....folding tables, plastic taps, ironing boards can develope "bows" in them over time....I finally ended up ordering an ironing board online which was expensive because the ones they had around here developed sagging parts in the surfaces and I was getting baggy yardage when I ironed it.....same with cutting strips on my cheap folding table....I now like to cut strips on my sewing cabinet which is wood or on my wooden heavy folding table...doesn much better so it isn't just ruler that can be causing problems....