THE LOOM
The loom can trace its genealogy away back to early Babylonian times, and the modern power-driven machine does not differ in its broad principles of operation from its ancient progenitor—the hand loom.
FIG. 68.—RING-SPINNING FRAME
FIG. 69.—THE HEDDLES OF A LOOM
Every industry has a vocabulary of its own to furnish names for its machine parts and products peculiar unto itself, and in this respect the textile industry is by no means an exception. The threads that run lengthwise in a piece of woven cloth are known as the “weft,” “woof” or “filling.” In the loom the warp threads are threaded through loops on what are known as “heddles”; in fact, there are two “heddles,” A and B, Figure 69. Alternate warp threads (C) pass through the loops of one heddle, and the other threads through the loops on the other heddle. When one heddle is raised and the other lowered, the threads form a wedge-shaped space (D) which is known as a “shed.” The filling thread is sent through the shed and is then pressed closely into the wedge-shaped space against the cloth already woven by means of a “reed” (E) which is a comblike member with teeth or flat pieces of metal that pass between the warp threads. This done, the position of the heddles is reversed, so that A is now lowered and B raised, thus binding the warp thread in place and forming another shed for the next warp thread; and thus the process continues.
The filling thread is placed in a shuttle (F) which carries a bobbin on which the thread is wound. As the shuttle is thrown back and forth through the shed, the thread is unwound and trails behind it. Formerly the shuttle was thrown back and forth by hand, but years ago, long before the invention of the steam engine, the flying shuttle was invented. In other words, a mechanism was provided for striking the shuttle a blow and throwing it across the warp from side to side. By this means the speed of operations was greatly increased.
About the middle of the eighteenth century the drop box was invented. This consists of a receptacle for shuttles carrying different colors of thread which may be selected in a definite order and thrown back and forth so as to vary the pattern of the cloth.
In present looms a special machine is provided for taking the threads from the bobbins or cops and laying them in an even sheet to form the warp of the loom. These are wound on a beam and the machine is known as a beam warper. As the threads are apt to be somewhat fuzzy it is necessary to size them, and a machine known as a slasher is employed for this purpose. This machine coats each thread of warp yarn with a sizing compound or an adhesive and dries the sheet of warp preparatory to its use in the loom.
In common weaving the weft or filling threads run alternately under and over the warp threads with perfect regularity. A pattern can be formed by passing the weft threads under and over alternate groups of warp threads, and this is effected in the ordinary loom by threading the weft in groups through the heddles, i. e., instead of having every second thread pass through one heddle and the intervening threads through the other heddle; the threads are arranged in alternate groups of two or more. This gives a regular pattern, but it may be varied to form ornamental designs if the groups are varied. Such designs used to be worked out by hand very slowly and laboriously, with the result that figured weaving was very expensive.