PURPOSE: To accurately process tooth to a base metal with a defect eliminated by screwing a female screw into the center part of the base metal formed with a material having a selflubricity, making a metal axis material to be threadedly engaged into the female screw of the base metal, threadedly engaging and tightening nuts, and thereby firmly fixing the base metal to the axis material.

CONSTITUTION: A female screw 3 is processed to the lower hole of the axis center part of a base metal 1 composed of a selflubricity sintered metal and having a size of a sufficient cutting part. Then an axis material 4 composed of a metal having a sufficient strength is processed to a given shape and size, and a male screw 5 is processed and formed to a part to which a toothed gear is to be intruded. Next the screw 5 is threadedly engaged into the screw 3 of the metal 1, furthermore, nuts 6a and 6b are threadedly engaged and tightened, and the metal 1 and the material 4 are firmly united. After the metal 1 is processed to a given size in the condition, the toothed gear can accurately be processed with a defect of the metal 1 eliminated by a cutting work of a spiral groove 7.