I haven't used the pipe cutters, but cut stainless periodically with abrasive disc cutters quite sucessfully. A trick shown to me years ago regarding cutting a tube (applies VERY WELL to large tubes) is to take a known squarely-cut sheet of paper (longer than the circumference of the tube) and wrap the tube with it with the edge of the paper on the proposed cut line. By lining up the paper edge as it is wrapped around the tube, the line it forms will be a perfect 90 degree cut-line.