Elastic and non-elastic narrow fabrics : $b and a chapter on narrow fabrics made on knitting machines — John Shaqi
Elastic and non-elastic narrow fabrics : $b and a chapter on narrow fabrics made on knitting machinesBrown, Samuel
History
Elastic and non-elastic narrow fabrics : $b and a chapter on narrow fabrics made on knitting machines
Brown, Samuel
Elastic fabrics; Looms; Rubber industry and trade; Textile fabrics; Weaving
The overshot method, which we have previously referred to, is another
form of double shuttle web which has in it elements of economy differing
from the cross shot but equally important. This kind of weaving is
designed as a substitute for silk jacquard webs, which it has to a great
extent supplemented. Before its introduction it was customary to use a
slow running “rise and fall” lay movement, when making a silk figure with
the shuttle, putting in one pick of silk filling to each two body picks,
so that the output of web was only about one-half of what is possible
in overshot weaving. In the old method the silk used to pass from edge
to edge of the goods at each pick of the figure shuttle, and where the
figure did not appear it was buried between the upper and the lower
cloths.
In the overshot method the silk figure is bound down at the edge or
border of the figure and none of the silk is entirely buried out of
sight. In the overshot the body shuttle runs all the time, while the
figure or silk shuttle only runs with every alternate pick. The main
body of the goods is woven in every respect the same as in a single
shuttle web, and it may embrace all the weaves, such as plains, twills
or fancies, which are common to single shuttle weaving. Arrangements are
made, however, for the production of an auxiliary shed, by a movement
which pulls certain threads above the main shed, and while these are
open to pass the extra shuttle under them, and thus bind in the figure
filling. The lower part of the lay has straight shuttles, while the
upper bank of shuttles is tipped down to conform to the formation of the
auxiliary shed they are designed to pass through.
The binder threads from which the overshot figure is generally operated,
are weighted very lightly so that the individual threads will easily
stand the strain they will be subject to while making the auxiliary
shed. The Crompton & Knowles overshot dobby is generally used for this
purpose. This special machine is provided with two horizontal draw
knives, operating any or all of the 30 hooks, and is so arranged that
the connected warp threads may be lifted at either or both picks to the
height of the main shed, or to the additional height of the auxiliary
shed.
[Illustration: Fig. 5.—Simple Overshot Design]
[Illustration: Fig. 5A.—Draft for Fig. 5]
In Fig. 5A is seen the draft of a simple overshot figure covering 23
hooks, which are operated from one knife drawing in unison with the
binder harness, while the other knife is operating on the alternate shed,
or the heavy pick, and working in unison with the rubber harness. It will
be noticed that in the overshot design both sides of the figure do not
operate alike, but follow one pick behind the other. This is so arranged
that the binder may come up at the right pick to properly bind down the
silk in the goods, and so avoid any irregularity or ragged appearance at
the border of the figure.
MAKING OVERSHOT DESIGNS
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