I have the Orbitol Rotary Sharpener (retail $37 in Canada) which does a reasonable job if the blade is not nicked. I find the first sharpening is about 75% as good as new, a second 50% and I usually can get a third use out of it. This really extends the life of your blade and to be safe they should be sharp. I shudder when I see quilters literally sawing through fabric. One pass is all it should take. I have found that Tailorform blades (Symak Sales) or Komfort Kut (H.A. Kidd)sold for $2.99 at Lens Mills and once a year or so on sale (half price) stand up to sharpening quite well and fit my Olfa cutters. When I find a good sale, I buy a dozen!