A locking assembly for the spindle of a tool includes a locking member, a biasing member interconnected with the locking member, and a collar surrounding a portion of the spindle. The spindle includes a spindle slot that receives the locking member to lock the spindle with respect to the tool housing. The collar may be rotated into an unlocked position in which the biasing member holds the locking member out of engagement with the spindle slot. The collar may also be rotated into a locked position in which a cam surface in the collar acts on the biasing member to apply a biasing force on the locking member toward engagement with the spindle slot. The biasing member may deflect to accommodate rotation of the collar into the locked position with the spindle slot not aligned with the locking member.