Sewing machine

Article By:

Rockett, Frank H. Engineering Consultant, Charlottesville, Virginia.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.617300

A mechanism that stitches cloth, leather, book pages, and other material by means of a double-pointed needle or an eye-pointed needle. In ordinary two-threaded machines, a lock stitch is formed (see illustration). An eye-pointed reciprocating needle carries an upper thread through the layers of fabric, forming a loop beneath the material. A shuttle carrying a bobbin of under thread passes through the loop. Alternatively, a rotary hook takes the loop of upper thread and passes it around the bobbin of under thread. The needle withdraws, and a thread take-up lever pulls the stitch tight. The machine carries out these necessary motions and also feeds the material past the needle intermittently between each pass of the needle. A presser foot held against the material with a yielding spring adjusts itself automatically to variations in thickness of material and allows the operator to turn the material as it feeds through the machine. A cluster of cams, any one of which can be selected to guide the needle arm, makes possible a variety of stitch patterns. See also: Cam mechanism

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