Jacquard Weaving and Designing

by T. F. Bell

Before starting the machine the needles should be examined to see that they are all free, and that they will spring out easily after being pressed back. The griffe should be perfectly horizontal and all the knives properly set; the holes in the cards and cylinder should exactly correspond, and when the cylinder comes in the needles should be fair in the centre of the holes; if not, the cylinder must be set as described (see description of Figs. 26 and 27).

The driving of heavy single-acting jacquards will be further considered under Twilling Jacquards.

When any of the hooks or needles in a jacquard get bent or broken, they can easily be straightened, or taken out and replaced by others. By putting a thin blade of iron or wood down through the needles alongside of the hook to be replaced, and springing open the passage, the old hook may be drawn out and a new one put into its place. The tail cord must, of course, be cut off the bottom of the hook, and a new one tied on. For changing a needle take off the spring-box and draw up the pin which fastens the row of needles at the back; then the needles in this row may be taken out till the defective one is reached, and the row made up again; or, the old one may be renewed without taking any of the others out. A flat blade is used to slide through the hooks and keep clear the place for the needle to be put in.

Card Frames.—The cards for jacquard work are usually hung on a frame as O, [Fig. 18], wires sufficiently long to catch on both sides of the frame being tied to the lacing of the cards. The number of cards between each wire may vary to suit the space and the quantity of cards. Sixteen to twenty suit very well, the former for small and the latter for larger sets, and for very small sets twelve or fourteen might be more convenient. The frame may be made of round iron rod, or of flat or bar iron, and should be of the shape shown in the sketch, and not semicircular, as is usually the case, which presses the cards together in the centre; almost flat at the bottom, with just enough of a slope to make the cards slide back, is much the best. Of course, for a few cards it does not matter much what shape it is. P ([Fig. 18]) is the frame for the rollers over which the cards travel to the cylinder. They should be so sloped as to make the cards travel up nicely with sufficient drag on them, and not too much; on this depends a good deal the proper working of the cards, particularly when the machine is running at a high speed, and when springs are not used to steady them on the cylinder. It is usual to have a roller below the cylinder, attached to the frame which holds the cylinder, and the falling cards pass over it. Sometimes the cards, when falling, are shaken, so that some of the wires may not catch on the frame, but pass through it, or the ends of some of the wires may be bent and cause the same result; if the weaver neglects to put these up on the frame before the cards work round to those that have fallen, the wire may catch on it and prevent the cylinder from turning, or, perhaps, pull it out. Sometimes a crank or bend is made in the frame at the outer end, so that the wires can pass up through it without catching. The frame should just be sufficiently wide to enable the cards to pass freely through it with, say, one-eighth of an inch clearance at each side; then, if three or four inches at the outer end is cranked, or set out so as to be a little wider between the two bars than the length of the wires, they will pass up through without catching. Frames of the shape described are, of course, only suitable when the cards are to be wrought forwards—that is, with the cards falling between the cylinder and the machine; but if they require to be wrought both backwards and forwards, as is sometimes the case, the card frame must be made more of a semicircular shape, and the rollers must be set so as to give a sufficient fall to the cards, and keep them firm on the cylinder.

As has already been said, the nature of the shedding of a single-acting jacquard is objectionable for speed in working, for ease on the yarn, and for heavy work, or for well-covered work. The jacquard harness is levelled so that the yarn is all sunk, and the shed is entirely a rising one; it can easily be understood that when the griffe rises to open one shed, it must again fall before it can begin to rise to form the next shed. Now, mostly all tappet motions, and a great many dobbies or shedding motions, either have the yarn springing up and down from the centre, or have one portion rising and the other portion falling at the same time, so that in them the second shed could be open at the same time that the griffe in the single-acting jacquard had fallen to begin to rise the second shed; but as this would be much too soon, they can take a greater time to accomplish the work, and thus have a much slower and steadier motion.

It has been attempted to work the single-acting jacquard on the centre-shedding principle, and machines are at present being made in France of this class. It is only necessary to let the board on which the upright hooks rest fall at the same time that the griffe is rising in order to accomplish what is required, and the method of working is good, and would suit well in dobbies where the heddles can be taken firmly down. But in the jacquard the drawback is in the harness: the constant rising and falling causes a vibration in it, and does not admit of nearly so firm work as when the rising shed alone is used.

Fig. 30

One of these machines is shown in [Fig. 30]; they are a very compact and neatly made machine, and contain a much greater number of hooks than one of the English machines. [Fig. 26] gives one of the hooks in this machine, and the way in which it acts is there explained. It will be seen that the frame for the cylinder is inverted; F is the face-plate or needle board as it rests when the cylinder is not pressing against it, being held in this position by the spring H pressing on a stud on the bar I, which extends from the face-plate to the clap-board G. The cylinder frame is driven by a rod, C, connected with a lever. E, E¹ are two racks on the ends of the hole board on which the hooks rest, and D, D are two levers with quadrant racks on each end, which work into the racks E and E¹, and also into the racks on the slide bar a¹. This slide bar is fastened to the griffe A A, which is raised by a connecting-rod from a horizontal lever to the stud a. As the griffe is raised one end of the racked levers, D, is also raised, and the other end sinks, taking down the hole board by pressing on the racks E and E¹. The hole board is fixed so that it will easily slide up and down. If the griffe is raised two inches, the hole board falls rather more than one inch.