Sewing Machine

A machine designed to join pieces of fabric or leather by means of a lockstitch or chain stitch. The lockstitch, which is used in most modern machines, is formed from two threads and the chain stitch from a single thread.

History
The first sewing machine was patented in 1790 by the British inventor Thomas Saint. Saint's machine, which was designed to sew leather and canvas, used only a single thread and formed a chain stitch. No needle was used; instead an awl was used to pierce a hole through the material being sewed. Another mechanism placed the thread over the hole, and then a needlelike rod with a forked point carried the thread through to the underside of the work, where a hook caught the thread and moved it forward for the next stitch. When the cycle was repeated, a second loop was formed on the underside of the cloth with the first loop, thus forming a chain and locking the stitch. Saint's machine, however, never progressed beyond the patent model stage.

A French tailor, Barthélemy Thimonnier, built the first practical sewing machine in 1829. It employed a hook-tipped needle that was moved downward by a foot treadle and returned by a spring. Like Saint's machine, it produced a chain stitch. When Thimonnier installed 80 of his machines in a clothing factory the tailors of Paris wrecked them, and eventually he died bankrupt in England.

The American inventor Walter Hunt devised the first lockstitch machine about 1834. The machine, which employed both an eye-pointed needle and an oscillating shuttle, was not patented at the time of its invention—so when Hunt later attempted to obtain a patent, his claim was disallowed on grounds of abandonment. Working independently, the American inventor Elias Howe devised a machine that contained the same essential features as Hunt's and patented it in 1846. Subsequently another American inventor, Isaac Merrit Singer, patented a similar machine and was successfully sued by Howe for infringement of Howe's patent. Singer, however, was instrumental in the pooling of various patents in the sewing-machine field and in laying the groundwork for the mass production of the machines.

Other important inventions in the field included the rotary bobbin that was incorporated in 1850 into a machine patented by the American inventor Allen Benjamin Wilson, and the intermittent four-motion feed for advancing the material between stitches, which was part of the same patent. Singer devised the presser foot, a spring-tension device for holding the material firmly against the worktable, after the patenting of his first machine.

The earliest successful sewing machines were powered by the turning of a hand crank. Later a foot-treadle and crank arrangement was incorporated, enabling the operator to use both hands in guiding the material under the needle. All modern sewing machines are now equipped with electric motors activated by means of foot-operated or knee-operated controllers.

Operation
For domestic sewing, either a straight-stitch or a zigzag sewing machine is used. In straight stitching, the needle moves up and down, producing a straight line of stitches; in zigzag stitching, the needle moves up and down and side to side, resulting in a zigzag line of stitching. The zigzag machine is equipped for decorative stitching, monogramming, overcasting, blindstitching, and sewing on buttons, making buttonholes, and mending.

Most modern sewing machines employ two separate threads to form a lockstitch. The upper thread is led through an eye formed near the point of a needle. The under thread is carried on a bobbin and is linked or locked to the upper thread by means of a rotary or horizontal motion of the bobbin. In a typical machine employing a rotary bobbin, the sequence of operations is as follows. The needle carrying the upper thread moves downward through the material being sewed, and the thread is engaged above the eye of the needle by a hook on the rim of the bobbin. As the bobbin turns, the upper thread is pulled out to form a loop through which the under thread feeds. A tension device on the upper part of the machine controls the size of the loop. As the needle withdraws, the locked loop formed by the two threads is tightened by the pull of a lever take-up device to form a stitch. In a machine employing a horizontal bobbin held in a freely moving shuttle, the stitch formed is exactly the same. The shuttle moves through the loop of thread as the needle comes down, and then the shuttle returns to its original position as the needle moves up.

In addition to the large number of machines available for home use, about 2,000 different types of industrial sewing machines are designed for the manufacture of hats, shoes, and hosiery, as well as for the sewing of garments. Modern machines, domestic and industrial, are equipped with microprocessors to carry out automatic sequences of operations.

Sewing Machine
People use sewing machines to design and create their own clothing and household items. Advanced models are used for the mass-production of these products in factories. In order to sew two pieces of fabric together, a machine must first be threaded. Starting from a spool on the top right-hand side, thread is passed through several guides to control its path and tension. It is eventually pulled through a small hole in the bottom of the needle. Another thread comes from a bobbin case beneath the feed dogs and sewing surface and is used with the top thread to form stitches. Pieces of fabric are carefully pinned together, then positioned near the needle. Finally, the presser foot is lowered to hold the fabric firmly against the feed dogs, which are two small rows of metal teeth that move the fabric forward at a uniform rate when a power pedal on the floor is depressed and sewing begins.