A machine tool includes a lever arm extended from a column, a working spindle and a guiding member attached to the lever arm and having an upper guiding surface and a lower recess formed by an anchoring surface, the guiding surface is located farther away from the column as compared with the anchoring surface of the guiding member, a tool cartridge is attached to the lever arm for supplying tool elements to the working spindle, and includes a seat having a cam surface, a guiding roller attached to the seat for engaging with the guiding surface of the guiding member and for selectively separating the tool cartridge from the working spindle and the guiding member.