specially adapted for making conical screws, e.g. wood-screws

Full Title

Thread cutting; Automatic machines specially designed therefor > on an external or internal cylindrical or conical surface, e.g. on recesses (B23G1/16, B23G1/22, B23G1/32, B23G1/36 take precedence) > Machines with a plurality of working spindles > specially adapted for making conical screws, e.g. wood-screws