The little blue sharpener I bought did not work very well. My son even sharpened a few blades for me, then said this thing is a waste of money. Now I go to Harbpr Freight Tools and buy 100 in a box for 15.00. They are called "carpet cutter" replacement blades and fit my 45mm rotary cutter. (They do not fit the 65mm). Now I change blades more often and end up with less frustration over skips!