A blade mounting assembly for mounting a rotary blade to an arbor comprises an outer washer including a hub configured to extend through a bore of the blade, the hub defining a central bore sized to receive a spindle of the arbor. The hub further includes a locating surface arranged to contact the shoulder when the spindle extends through the central bore. The washer includes an engagement surface contacting the left side face of the blade when the hub extends through the bore of the blade. The engagement surface is disposed a fixed axial distance from the locating surface relative to the length of the hub. A fastener engages the outer washer to the arbor with the locating surface in contact with the shoulder. The assembly further includes a biasing element configured to be disposed over the hub between the shoulder and the right side face of the blade.