A cutting tool clamp mechanism for a power tool includes a housing supported by a spindle, the spindle being configured to receive and drive a cutting tool along a longitudinal axis of the spindle. A clamping system is supported by the housing and includes an engaging portion movable relative to the spindle, the clamping system having an engaged condition, in which the engaging portion is engageable with the cutting tool to secure the cutting tool in the spindle, and a released condition, in which the engaging portion is disengageable with the cutting tool. A biasing member is positioned between the housing and the clamping system, and operable to bias the clamping system to the engaged condition. When the cutting tool is removed from the spindle, the clamping system is held in the released condition, and upon insertion of the cutting tool into the housing, the clamping system moves from the released condition to the engaged condition.