Subclass 1/14: Thread cutting; Automatic machines specially designed therefor on an external or internal cylindrical or conical surface, e.g. on recesses (B23G 1/16, B23G 1/22, B23G 1/32, B23G 1/36 take precedence) Machines with a toothed cutter in the shape of a spur gear or the like which is rotated to generate the thread profile as the work rotates specially adapted for making conical screws, e.g. wood-screws