If it takes more than one pass of the rotary cutter to cut through fabric, it might be time to change the blade. Disassemble the parts of the cutter and lay them out in the correct order for easy assembly. I keep a container marked for used blades and when there's 4-5 in there I toss the lot. Use a Sharpie pen to write the month/yr. on the new blade to keep track of when you changed blades. Periodically check your blades by cutting strips of scrap fabric. Sometimes loosening the nut on the cutter will result in a smoother cut; these are often too tight when taken from the package so try this and it could improve cutting without having to change the blade.
Copyright Sharon Baggs, 2008