The invented hob is suitable for machining the involute gear, non-involute gear and the spline tooth. Its characteristic changes the original separate structure of hob and cutter arbor into an integral arbor structure, on which the axial notch is cut and in said notch the coarse cutting bit and fine cutting bit are super posed. At two ends of the notch there are shaft shoulder locating piece, holddown washer and holddown nut separately to make the coarse and fine cutting bits axially located. The advantages are good integral rigidity, high accuracy for working component part, convenient for assembling and disassembling bit, capable of regrinding coarse cutting bit, the fine cutting bit is disposable, simple for machining the coarse and fine cutting bits and capable of bulk prodn. |