Jacquard Weaving and Designing

by T. F. Bell

The shed should be closed, and begin to open again when the reed is at the fell of the cloth. Too large a shed should not be made with the doups, on account of the strain on the yarn: a small clear shed gives much more satisfactory work. The front cumber board, containing the doup leashes, may be shifted a little forward or back if thought desirable, so as to get the cross shed to spring as easily as possible, the amount of elasticity in the warp varying this considerably. The slip heald is raised for every shot by cording it to the brander or griffe of the jacquard, which for gauze work is generally a single-acting one. Springs are used for holding down the slip—a light wire spring, or, better, a piece of round indiarubber about 3/16 in. in diameter, doubled if necessary. Bridles should be attached from the shaft of the slip heald at each end and fastened to the cumber board so as to bear the draw of the springs when the harness is down; the cords connected with the jacquard for raising this shaft may then be left slack, and the size of shed may be regulated or made less than the draw of the machine, if required.

It is very important to have the doups nicely adjusted; on this depends their lasting capacity, and sometimes a very short time is sufficient to cut them to pieces if badly set. But if correctly done they will generally last for a length of time, particularly if occasionally turned on the shaft, which is more essential in working with a linen than with a cotton warp.

One of the doup standard mails with a doup through it is shown at No. 1 ([Fig. 138]), where it may be seen that the doup is simply drawn through the eye of the mail, and not connected with it in any way. It is only held in this position by the warp thread passing through it, and whenever the thread breaks the doup falls out of the mail. This is a trouble to the weaver, at least till she gets accustomed to it, and mails, as shown at No. 2, have been made to hold up the doup. The remedy here is often worse than the evil. The mails wear the doups, particularly if the springs draw them tight down on the eyes of the mails; and besides, they have the disadvantage that the slip heald has to be built in them after the harness is mounted, whereas with the open mails the slips can be procured anywhere quite independent of the harness. The slip heald must be set so that when the harness is down the yarn will not be drawn through the eyes of the mails by the doup sinking too low. This may be guarded against by adjusting the bridles at each side, between the slip shaft and the cumber board. The loops of the doups should pass about 1/4 in. through the eyes of the mails when at the lowest or bottom position, and the front mails being about 1/4 in. lower than the others allows the loops of the doups to be just bearing lightly on the warp, all being held up straight. The slackening bar must be arranged to work in time with the doup standards, and should not slacken the yarn too much nor too little, just keeping it at a uniform tension. The great point with tender or weak yarn is to reduce all friction to a minimum, no matter by what it is caused, and if this is done the yarn and doups, if they are of a fair quality to begin with, should both work well; but a very slight difference in setting the doup may make a great deal of difference in the working of it. A doup that may be cut to pieces in working 20 yards of cloth might work 400 or 500 yards with so little alteration as not to be noticeable to those not accustomed to the work. The slackening bar must not rise so high as to raise the yarn that is above it, nor must it sink so low as to press the whip down on the back harness board, and it must be so regulated that within these limits it will give the proper amount of slackening, and prevent the whip warp from getting tight and drawing up the small back harness.

Fig. 138

Worsted makes the best weaving doups for strong work, but for lighter work cotton is mostly used, being finer and cheaper. Sometimes polished linen yarn is used and makes a very smooth doup, but does not give the wear.

Small metallic rings are sometimes used on the loops of the doups, and the warp drawn through these rings; this suits for yarn with much fibre on it, as it keeps the fibre from getting twisted into the doups, but the rings cut the doups faster than ordinary yarn working in them would.

Instead of a slip heald in front, doups with a lingo on each have been used, with the mails for the standards as shown at No. 2, Fig. 138, so that the doups cannot fall out of them, and the yarn when drawn up by the back harness in shedding raises the doups and lingoes up with it. The weight of the lingoes must be such as will suit the strength of the warp to be used—not too heavy for it to lift nor too light, so that in the cross shed the doups would be drawn through the mails. These doups being separate, are easily built in the harness and very easily repaired by the weaver when they break, but they break too frequently. It is, of course, only for a strong warp that this method of working is suitable, and even for it, although it works very well, the principle is not good.