The blade holder has a movable plate and a fixture. A rotatable bolt in operative engagement with a block attached to the plate. A motor is in operative engagement with the bolt. The motor rotates the bolt to move the plate towards the fixture to grip a first set of blades until a torque threshold value is reached. The processor determines a number of blades included in the set of blades based on the number of rotations of the bolt. A first grinding portion of a rotating abrasive belt is applied against the set of blades (having width (W