mloquilts

I have a whole set of these rulers that I got from Nancy's Notions several months ago. As far as I'm concerned, they don't sharpen my blades. In fact, they seem to dull them. The rough edge is only on one side of the ruler, so they can be used as one would any ruler, cutting from the other edges. One thing I do like about them is that they have a non slip back so they do stay in place well. I even called the manufacturer asking if I was holding my cutter wrong, but the guy I talked to said it shouldn't make any difference. Anyway, they are of good quality but I wouldn't buy them thinking they will sharpen your blades. Has anyone been able to sharpen their blades using this ruler?