Detecting assembly for a multi-axis machine tool

A detecting assembly for multi-axis machine tools having a spindle and a turntable and has a detector, a lens device and a computer. The detector is connected to the spindle and has a mounting frame and two detecting segments. The mounting frame is connected to the spindle and has a connecting rod, a bottom board and multiple mounting boards. The detecting segments are mounted on the mounting boards and each has a light source and a sensor. The lens device is mounted on the turntable, extends into the detector and has a supporting shaft and a spherical lens. The spherical lens is mounted on an upper end of the supporting shaft to align light emitted from the light sources with corresponding sensors via the spherical lens. The computer is electrically connected to the detector to receive signals of the detecting segments of the detector and has a signal processor.