Axial length indexable adjusting type combined tool and using method thereof

The invention belongs to the technical field of machining, and particularly relates to an axial length indexable adjusting type combined tool and a using method thereof. The combined tool comprises stop iron, a transposition disc and a positioning disc. The stop iron is used for reference positioning when being fixed on a lathe guide rail; a plurality of threaded blind holes are formed in the left side face of the transposition disc, and positioning screws are installed in at least two threaded blind holes. The transposition disc is installed on the positioning disc in a rotatable mode, and the positioning screw used for reference can be selected by rotating the transposition disc on the positioning disc. The combined tool can be used for assisting a common lathe in machining a multi-step shaft or a multi-step hole, the turning length of the step section is referenced and positioned by using a plurality of positioning screw rods with different lengths, rapid machining can be realized, repeated measurement wit