A lawn mower cutting blade spindle assembly having an elongate spindle shaft and a spindle shoulder projecting radially outward from the lower end thereof. A bearing assembly mounted within a spindle housing provides rotational support for the spindle shaft. Mounted on the upper end of the spindle shaft is at least one pulley configured to be driven by a drive belt connected to the mower's engine. A compression nut screwed onto the upper end of the spindle shaft is used to place the pulley or pulleys and bearing assembly in compression against the top face of the spindle shoulder. The spindle assembly also includes a cutting blade attached to the bottom face of the spindle shaft with a through-bolt and cutting blade attachment nut. Significantly, the cutting blade can be detached from the bottom face of the spindle shoulder without disturbing the compression placed on the pulley or pulleys and bearing assembly.
