The 45mm Rotary Cutter is the most popular size rotary cutter of all. It cuts a wide variety of fabric, paper, felt and works great when cutting multiple layers of thin materials. To unlock the sliding button, push down on the small button while sliding. The blade should glide freely over fabric. To alter the blade movement, turn the screw toward HEAVY for tightening and LIGHT for loosening. Tungsten Steel Blade. Integrated Blade Cover.