The Dahle 517 Guillotine has 2 blades, an Upper Blade and Lower Blade.
The Upper blade is the obvious blade that has a handle on the mounting, and is moved during operation of the guillotine. The Lower Blade is less obvious because it is static and is attached to the edge of the base of the guillotine.
The cutting action of the guillotine is a shearing action generated between the 2 blades, as the Upper Blade is Lowered against the Lower Blade.
Both blades will wear over time with usage. Replacement of the blades will restore the cutting abiltiy of your machine.
We recommend that they are both replaced at the same time in order to properly retore the cutiinng ability of the machine.