Automatic Closing Machines is used for side- and inside seams of trousers. It is applicable for a lot of different purposes. It has stepper motor for steering upper feed and control board. It consists of a powered rotary hammer for continuous application of a hammering force to the edge portion of a joint to be fold into a closed joint. A supporting frame with a vertically adjustable support permits varying the relative vertical spacing of the edge of the duct and the rotary hammer. The traversing mechanism automatically moves the rotary hammer back and forth along the track. It varies the distance of movement of the rotary hammer for any selected duct length. The apparatus is forming both for one-piece duct joints and two-piece duct joints.