Review on HFS (R) Heavy Duty Guillotine Paper Cutter -12'': Precision Cutting with Razor Sharp Paper Cutter Blade by Michelle Langley

There is probably no one in the world who has more experience with this type of paper cutter than I do. To understand why this and all similar wire cutters don't cut straight, consider the cutting mechanism. It is essentially a horizontal arm with a blade on the left end and a handle on the right end. Since the structure holding this mechanism in place is not 100% rigid, the whole mechanism rotates clockwise slightly when you pull down on the handle (which is on the right side). This clockwise rotation causes the blades to cut at say 180.25 degrees instead of the desired 180 degrees. Because the paper at the bottom of the stack is more subject to the full skew effect than the paper at the top, these sheets are shorter. Cutting thinner stacks minimizes the problem. Also, sharper blades help since you don't have to apply as much torque to cause rotation.