Cotton Weaving and Designing / 6th Edition

by John T. Taylor

Another and quite distinct effect is produced with doups. This is commonly called “lace” or net, and is often combined with gauze or other “open” leno effect in stripes known as “lace and leno stripes.” This lace effect is produced by making a thick end form a zigzag on the plain ground. The interlacing of the threads in a simple lace or net stripe is shown at [Fig. 139]. A thick end, A, is brought up first on one side and then on the other side of two plain or nearly plain ends, B and C. There are ten picks to the round, and by the side of this dent there is another thick end twisting in the opposite direction, first up one side, and then up the other of two more plain or nearly plain ends. Each thick end comes up for two picks at one side and then crosses under and comes up on the other side after an interval of three picks, and vice versâ. The marks represent the ends lifted. By the side of the lace there are two plain ends shown, which represent the unlimited number of ends used for the ground of the fabric. In weaving this pattern the draft and pegging given at [Fig. 140] would be used. By carefully following the design with the draft and pegging plan the principle will be easily mastered. The arrangement of the shafts is rather important. The doup is placed in front, the ground staves next, and the leno or net staves next. It is immaterial whether the crossing ends be taken through the first stave of the three used for the leno, or the back one—some prefer one way, some another—but it is necessary to get the leno staves as far back as possible to give the thread a better chance of crossing. Four staves are taken for the plain, as in ordinary weaving, to prevent overcrowding. The lifting marks on the pegging plan will be easily followed if the one in [Fig. 138] was understood. Where the fifth stave is lifted the loose half is lifted also, and both thick threads come up on the inside. Where the doup is lifted the slackener is lifted also, and the ends are brought up on the outside as on the sixth and seventh picks. More will be said on the arrangement of shafts in the chapter dealing with designs for leno. The explanations on the structure of the fabrics at this point are only for the purpose of enabling the requirements of the looms for weaving them to be understood. Some manufacturers prefer to work with the doups at the top of the loom, especially in weaving net lenos. In this case the crossing end is crossed over the others and slipped downwards.

It used to be considered that gauze and lenos could not be woven on double-lift machines. In other places than Lancashire this idea prevails to-day to a great extent, but of course this is a great mistake. The simpler kinds of lenos, such as pure gauze and crossovers, are sometimes woven on tappets, which are, of course, double-lift. The tappets are of the ordinary kind, drawn on the same principle as described earlier in this book; but the tappet which operates the standard ends is made to lift the staves halfway when the doup end is crossing. Tappets of this kind have been used for some time past, and it is not surprising that the same principle should be applied to double-lift dobbies. Instead of drawing the tappets to lift the standard ends half way or a little way to enable the ends to cross easier, the easing motion usually employed for dobbies is often used, and the tappets are of the ordinary kind.

In a double-lift dobby the healds begin to lift for one pick when the healds which are up for the previous pick begin to come down. In the case of [Fig. 137], when the doup is lifted for the first pick and begins to come down, the same end is being taken up the other side of B by the stave No. 1 being lifted. If the end B were not moved it would very soon be broken by the crossing end being made to act in this saw-like manner upon it. It is necessary, therefore, to lift the end B about halfway up at the moment the crossing end begins to come down and to pass to the other side of B. If the end A has not to cross for the next pick, it would not be necessary to lift the end B at all. In a single-lift machine the doup will get to the bottom before the first stave begins to rise, and therefore there would be no difficulty in the end crossing. In a double-lift dobby the staves containing the ends round which the doup thread crosses are lifted partly up every pick by a lever worked from the crank arm of the loom. This easing motion or “shaker” is shown at [Fig. 141]. AB is the crank-arm, and the upright CD is connected to the crank-arm at C, and to a lever ED at D. EG is another lever on the rod E, and the healds which are to be lifted half way are connected to this lever at G, as well as to the jacks in the dobby. As the crank revolves the oscillation of the crank arm imparts a similar movement to the lever ED, and to the staves which are connected to EG. This motion commences just at the proper time. Of course, when the crank-arm is lifting the healds, the cords connecting these healds to the dobby will be slack, as indicated at [Fig. 141]. By thus lifting the standard healds, the crossing is greatly facilitated.

FIG. 141.

This easing motion is not required where there is no crossing of the end immediately, as, for instance, in [Fig. 139], the doup end after being brought up on one side is never required up on the other side on the pick immediately succeeding, therefore the end has time to get down before being lifted on the other side and an easing motion is not required.

FIG. 142.

The method of slackening the warp when the doup lifts is shown at [Fig. 142]. This diagram shows a two-doup arrangement. For gauze and similar weaves it is not necessary to have a separate beam for the crossing warp, as one end pulls the other and the take-up is about the same; but for net lenos or laces after the manner of the fabric in [Fig. 139] it is necessary to have the crossing ends on a separate beam, as a great deal more in length of this warp is required than for the plain. Sometimes several beams are used, the only limit being the number which can be placed in a given space.

At [Fig. 142] the crossing warp from the bottom beam is taken over the slackening rod A, and over the carrier E. The crossing warp from the top beam is taken under the slackening rod B. A moves about a centre D, and B moves about a centre C.