Abstract: Deflection of cutting tools during machining on a lathe affects their tool life, surface roughness and dimensional correctness. For an optimum turning operation, correct selection of cutting parameters as well as tool extension length are essential. In this work, deflection of a T-42 CT H.S.S single point cutting tool is investigated by varying rake angle, cutting feed and tool extension length during turning operation on lathe. The selection of process parameters were determined by using Taguchi’s experimental design method. Cutting force components during turning operation were measured by lathe tool force dynamometer and detailed deflection analysis was conducted by using ABAQUS finite element program.