Abstract: A lathe has a bed, a rack and a mechanized tailstock assembly. The bed has a track having a chamber and a slot. The rack is connected securely to the bed. The mechanized tailstock assembly is movably mounted to the bed and has an outer guide, two moving guiding brackets and a drive device. The outer guide is movably mounted on the bed aligning with the slot. The guiding brackets are respectively connected to the outer guide, extend into the chamber of the track and each guiding bracket has a guide wheel. The drive device is connected securely to the outer guide, engages with the rack and has a casing, a drive axle and a drive wheel. The mechanized tailstock can be moved simply and easily and accurately using the drive device and the guide brackets prevent it from falling away from the surface.