__________ is used to move the carriage automatically during threading.

Explanation

Explanation:- The lead screw is used to move the carriage automatically during threading. sin θ = ​L h sin θ = ​ L H The lead screw is a long threaded shaft used as a master screw. It is brought into operation during thread cutting to move the carriage to a calculated distance Mostly lead screws are acme threaded. Important Points The bed is mounted on the legs of the lathe which are bolted to the floor. It is made of cast iron and its top surface is machined accurately and precisely. The feed rod is placed parallel to the lead screw on the front side of the bed. It is a long shaft which has a keyway along its length, The carriage handwheel is used to manually position and/or hand feed the carriage in the longitudinal or axis.