A bit holder has a shank at a proximal end thereof and a blind bit-accepting hole at a distal end thereof, shaped to receive a correspondingly-shaped tool bit. The bit holder has at least one locking mechanism which includes an angled path defined in the bit holder, opening into a side of the bit-accepting hole, extending away from the bit-accepting hole in a proximal direction at an acute angle A from a central axis. A locking element is slideable in the path. A sleeve around the shank is biased towards the bit-accepting hole by a spring, such that a distal end of the locking element extends slightly into the bit-accepting hole. Moving the sleeve towards the proximal end of the bit holder retracts the locking element from the bit-accepting hole, thereby releasing the bit. A spring-loaded plunger in the blind hole may be used to eject the bit automatically when the locking mechanism is released by the sleeve.

A machine tool includes: a frame; a hollow ram disposed on the frame in a reciprocable manner; a hollow spindle to which a tool is mountable, rotatably supported by the ram, and having a lever hole penetrating the spindle in a radial direction and extending in an axial direction; a drawbar including a collet, reciprocate in the spindle, and urged toward a basal end of the spindle; a lever connected to the drawbar and extending radially outward of the spindle through the lever hole; a trigger fixed to the frame; a feed unit that reciprocates the ram, advances the ram toward a distal end to machine a workpiece, and retracts the ram toward a basal end to bring the lever into contact with the trigger for the drawbar to advance with respect to the spindle to open the collet.