A machine for sewing cloth, leather, or books: a major industrial
and domestic labor-saving device. There are two main types: chain-stitch
machines, using a needle and only one thread, with a stitch that pulls each
looped stitch through the next; and lock-stitch machines, using two threads,
one through the needle eye and one the other, which interlocks with the
first in the material, from a bobbin/shuttle system (to-and-fro and rotatory).
Chain-stitch machines – the first to be invented, by Barthélemy
Thimmonier (1793–1859) – are now chiefly used for sacks or bags.
The lock-stitch machines now in general use are based on that invented by
Elias Howe (1846). Zigzag machines differ from
ordinary straight-stitch machines in having variously shaped cams
that move the needle from side to side.
|Cutaway of an electrically powered domestic sewing
machine using the lock-stitch system. Power is supplied by belt to
the main upper shaft which in turn drives the needle bar up and down
via a crank. Power is also supplied from the main shaft to the bobbin
and rotating hook under the working platform and via cams to the feed
dogs which move the material being sewn to across the working platform
under the pressure foot. Zigzag stitches are made by swinging the
needle bar to and fro at right angles to the path of the material.
Variously shaped cams can be loaded into the top of the machine to
control the needle bar, rotatory hook, and feed dogs for automatic
embroidery and fancy stitches.