Chapter III.

Chapter III.Head Motion Looms and Dobbies for Making Fancy Effects—Tying Up Harness—Construction of Loom Webs, Lisle Webs, French Web or Railroad Weave and Cable Webs—Making Good Selvages and Preventing Long-Sided Effect

Head Motion Looms and Dobbies for Making Fancy Effects—Tying Up Harness—Construction of Loom Webs, Lisle Webs, French Web or Railroad Weave and Cable Webs—Making Good Selvages and Preventing Long-Sided Effect

So far we have mentioned only plain looms, or those limited to the capacity of eight or twelve pick cams. Before we consider any of the varied constructions relating to elastic webs it will be well to speak of fancy looms. There are different types, adapted to a wide range of fancy effects, but the fancy loom most generally used is what is known as the chain head, an example of which is shown at Fig. 1. Such looms are usually of 18 and 24 harness capacity, and are operated by a figure chain of the length required to produce the desired figure. Chains are made up of a series of bars, one bar operating with each pick of the loom and having on it space for a roller or sinker for each harness to be operated.

Wherever a roller is placed on the bar, the corresponding harness will be raised, and wherever a sinker is used, the corresponding harness will be dropped. A series of rollers following each other will hold the harness up, and likewise a series of sinkers following each other will keep the harness down, thus maintaining at all times an open shed.

The shedding operation is very simple. In the fancy head there are two cylinders, each of which has gear teeth running the entire length. These cylinders operate continuously in opposite directions. The teeth of the cylinders do not go around the entire circumference as will be noticed on the upper cylinder shown in Fig. 1, but there is a blank space provided so as to allow for the engaging of the gear wheels brought into position at the right time as the cylinders revolve.

Between the two cylinders are vibrator gears, one for each harness, and to these gears are attached arms which are connected with the different harnesses. These vibrator gears can be thrown into position by the chain rollers or sinkers, so as to come in contact with the teeth of either the upper or lower cylinder, and are so timed that they take their position at the moment when the blank part of the cylinder presents itself. A vibrator gear engaging the upper cylinder is turned so as to lift the harness connected with it, while a vibrator gear engaging the lower cylinder drops that particular harness. The harnesses stay in their relative positions until the chain calls for another change.

Both cylinders and engaging gears are made of hard chilled steel, so that wear and tear by hammering at the time of engagement are reduced to a minimum. To further soften the engagement, the speed of the cylinder is controlled by elliptical driving gears, which reduce the speed of travel just at the moment when the engagement takes place.

The timing of the various movements of the head is so well controlled that there is little risk of any part failing to maintain proper relationship with the other parts. But in the event of any accident or breakage occurring which interferes with the free motion of the head, such strain is taken care of by a soft pointed set screw on the head driving shaft, which shears off and so prevents further serious damage.

The capacity of the head is such that by careful arrangement of figures and repeats it is quite possible to make several simple designs to run side by side in the same harnesses and this is often done. Of this we may write more later.

Fig. 1.—Fancy Loom for Weaving Narrow Fabrics

Fig. 2.—Double Index DobbyFig. 3.—Overshot Dobby

Fig. 2.—Double Index Dobby

Fig. 3.—Overshot Dobby

A popular machine for light fancy warp figures is the overhead dobby shown at Fig. 2, which may be used as auxiliary either to the plain cam loom or the fancy head loom. It is placed on a well braced, rigid frame and built as high as convenient so as to reduce the angle of the harness strings. It is driven directly from a two to one shaft, which may be either underneath the loom or at the end, and is connected with a threaded adjustable rod, which is attached to a slotted lever and can be adjusted to govern the depth of the dobby shed.

It is customary to put two of these dobby machines over each loom, but having only one main drive the two machines are coupled together and work in unison. Such an arrangement has the double advantage of a less acute angle at the harness tie-up, and also affords facilities for a distinctly different pattern on either half of the loom. It minimizes the risk of the harness threads cutting into the compart boards, and prolongs relatively the life of the dobby harness. Furthermore it allows for a straight tie-up on either machine so that there is no limitation to the length or character of the design, as is often the case where two patterns are run together on the same machine, or where point tie-ups are used, as would very likely be necessary if only one machine was installed to cover different designs on both halves of the loom. As we have previously stated it is not advisable to limit capacity for the saving of a few dollars in the initial cost.

Another type of loom employed in the making of fancy goods is what is known as the overshot loom. It is used for the introduction of a silk weft figure effect, and is probably the most pronounced form of elaboration introduced. It differs from the old rise and fall method in the economy of operation. The overshot continues to weave the body of the goods right along while the auxiliary shuttle is putting the silk figure in at the same time. Not only is it economical in the respect of greater yardage, but the method employed in binding the figure limits the use of silk to the actual figure displayed, and does not carry the silk, which is the most expensive material in the fabric, to the extreme selvage at every pick, as is the case where the rise and fall method is employed.

In the overshot system a specially designed dobby, shown at Fig. 3, is used for operating the lightly weighted threads of the binder warps. Two pairs of knives are employed, one of each pair operating far enough to raise the threads used in the binder warp to the level of the top main shed, while the other one of each pair carries the threads which are used for figure purposes to a higher level, so that the overshot shuttle may pass under them. This occurs every alternate pick of the loom, the body shuttle making two picks while the upper or overshot shuttle makes only one.

In levelling the harness, setting or timing of the loom, and making the shed for overshot work, the plans followed are identically the same as in ordinary single shuttle work, as the upper shuttle and upper shed are distinctly auxiliary and subordinate to the main shed. The binder warp, being necessarily but lightly weighted in its relationship to the upper and lower cloths it is binding together, allows for the figure threads to be strained out of their normal position, so that the upper shuttle may pass under them. In order to conform to this strained position of the binder figure threads, the upper shuttle must be acutely pitched downward at the nose so as to get a good clearance, and thus avoid any binding in its passages through the shed. This peculiar downward pitch of the shuttle is very important and cannot be over emphasized. It is shown in Fig. 4.

The overshot dobby is so constructed that a different set of draw knives operate on each alternate pick of the loom, one on the binder lift and the other on the rubber lift. This not only allows for a silk figure made with the shuttle but affords facilities for the introduction of a warp figure also, a combination which can often be made very effective, as shown in Fig. 5.

Fig. 4.—Showing Auxiliary Shed and Pitched Shuttle as Used in Overshot Work

Too much importance cannot be attached to the rigging of the dobby harness. A 30/9 ply linen cord is desirable and a lingo of about 16 to the pound. After deciding on the character of the tie-up required, and when the harness has been threaded in the compart boards, the lingoes should be looped on the strings, and then left to stand and settle for a couple of days before leveling. It is better still to run the dobby machine for a few hours, lifting all the harness and then dropping them, so as to settle the strings and take out any kinks or loose places which are bound to exist in a highly cabled linen cord of this character.

The labor required in the tying up and leveling of a string harness suggests the advisability of great care in determining the tie-up to be used, so that changes of pattern can be made easily without involving changes in the tie-up. In order to prolong the life of the harness, in the adjustment of which so much time and care must necessarily be spent, it is advisable to apply a dressing of boiled linseed oil, which should be thoroughly worked into the strings by running the harness for several hours, using one and one change cards. This should be followed by a dusting of talc or soapstone, which will add much to the smoothness of the finish.

To reduce the friction of the strings which operate in the several outside compart boards, where the strain and wear are particularly acute, and also to prevent the strings from cutting into the boards themselves, it is good practice to fix strips of ground glass between the different rows of strings, just above the compart boards. These strips of glass may be threaded through drilled holes in the compart board frame.

Before enlarging further on details of fancy looms, it will be well to retrace our steps and consider the construction of some of the simpler forms of web, such as are made on what we have described as plain looms. The webs best known, perhaps, are those such as are used for men’s ordinary garter wear, and for cutting up to retail in the regular dry goodsand notions trade. They vary from one-quarter to 2 inches in width. There are several distinct classes of these goods, the best known of which are the loom webs, the lisles and the cables, all of which are of single cloth construction, in which the filling is the main feature. There are generally two cotton warps used in such goods, one of which is commonly called the binder and weaves two up and two down, while the other is called the gut or filler, and works with the rubber warp, one up and one down. The selvages of these webs are made with the filling, which passes around a wire at each pick, the wire remaining stationary while the web is taken away from it in the process of weaving. An illustration of a loom web of this character is shown at Fig. 6. The draft and cam arrangement are shown at Fig. 6A.

Fig. 5.—Combination Warp and Shuttle Figure Produced on Overshot Dobby.

Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10

It is customary in some factories to use only one harness to carry both rubber and gut, inasmuch as the weaving of the two are the same and they both go in the same cavity or pocket of the web. Where such a method is employed there is always a tendency for the gut threads to get out of their proper places, and to fall together in pairs at irregular points, which will produce an objectionable “rowey” appearance in the goods. This will be noticed more particularly in white and light colored webs.

Fig. 6A.—Harness Draft and Weave for Three-Quarter Inch Loom Web

Fig. 7A.—Harness Draft and Weave for One-Half Inch Lisle Web

Fig. 8A.—Harness Draft and Weave for Three-Quarter Inch French Web

Fig. 9A.—Harness Draft and Weave for Three-Quarter Inch Cable Web

In the harness draft shown, it will be seen that one harness is employed for the rubber and one for the gut. It is thus possible to shed the gut harness so as to open more than the rubber, having it travel both higher and lower than the rubber harness at each alternate pick of the loom. By this movement the gut threads will be kept in the desired position, and at the same relative side of the rubber threads in each of the several pockets designed to carry them both. If, from any unusual cause, any of the gut threads get away from their proper places it is easy by this arrangement of separation to lift the gut harness at any time, insert a thread of cotton between the gut and rubber threads, and put them in their proper places when commencing to weave again.

The weave employed in the making of webs of this kind, although of a very simple character, involves a condition which does not favor a straight well woven fabric unless great care is taken to offset troublesome tendencies. The nature of the weave is such that at one pick the binder harness changes, while on the next pick it remains open and does not change, the rubber and gut harness changing only. The result of this movement is such that one shed clears for the reception of the filling much better than the other, so that at one side of the web the filling will hug the edge wire, shown at W in Fig. 6A, while at the other side of the web the failure to get a good clearance prevents the filling getting so snugly around the wire. Therefore, as the web draws away from the edge wire in the process of weaving, the tendency is for one selvage rubber cavity to be small, while the other is large, which means that at the open side there is a freedom for contraction of the edge rubber which is not present at the other side, and a long-sided uneven web is the result.

To counteract this it is essential that great care should be taken to get a good clearance of the shed. The shed should be timed as early as possible, so as to give every particle of fibre on the warp a good chance to separate and clear itself. When space permits, the front reed should be set slightly over on one side of the reed space, so as to create a little longer pull on the filling as it draws from the shuttle on the open side, and correspondingly eases up the draw of the filling on the other side. The warp stock used, however, may be of such a character that the loose fibre on it makes even these precautions ineffective altogether to counteract the trouble, and it may then become advisable to put in a fine edge wire on the open side of the web to offset the creeping tendency of the selvage rubber thread when contraction takes place after the web comes through the press rolls.

The feature which is aimed at, and which is most desirable in the appearance of such goods, is a clean cut prominent rib at the rubber line, and the avoidance of a flat paper-like look and feel of the web generally. The prominence of the rib varies, of course, according to the size of the rubber thread used, and the binder warp employed in dividing the same, but even the very best of conditions may be spoiled if proper care is not taken to get all the prominence of rib possible. Use as fine a binder warp as is practicable, compensating for any loss of weight or excess of contraction by using a heavier gut, which again of itself helps to fill in the rubber cavity and thereby lends additional prominence to the rib. All the weight possible should be carried on the binder warp up to a point of safety, and care should be taken to get a very easy, uniform delivery of the warp from the beam so as to avoid any erratic jerky movement of the warp lever.

The warp beams which are used on this delicate type of work should be well balanced and true to center, and the flanges free from any irregularity which would in any way interfere with the easy and uniform operation of the warp lever.

The gut, which weaves in with the rubber thread, is used for the two-fold purpose of giving additional body to the fabric and of regulating in a measure the length of stretch in the goods. The more gut there is used, the less becomes the power of contraction of the rubber warp, and the shorter the stretch produced.

Aside from the fineness and body of the goods, the element of stretch largely governs the market value of the fabric, so that good judgment and great care must be exercised in the assembling of the different sizes of yarns used. Weft, binder and gut all play their part in the governing of the stretch, as also does the number of picks put in the goods. Any excess of weight on the binder warp also materially reduces the stretch. In fact, any one of these features, wrongly adjusted, may result in the difference between the profit and loss.

In making the selvage of these goods a hard steel wire is used, around which the filling passes at each pick. This wire, shown at W in Fig. 6A, is highly tempered piano wire, of the very best quality obtainable. Sharpened to a needle point at one end, with a loop turned at the other end, it is fastened at the back of the loom by a cord which has an adjustable slip knot, so as to be able easily and quickly to regulate the length of wire running in the web. It is then passed through a harness heddle eye on the rubber or gut shaft, and through a reed space next outside the selvage rubber thread. The constant wear of this wire on the reed dent makes it necessary to have this dent of hardened steel so as to withstand the constant wear of the wire, which is always being crowded against the dent by the nipping action of the filling as it draws against the wire in the process of weaving, and the repeated beat at the same place in the dent at the weaving line. In any event, after a short time the dents in the reed will be cut so that it becomes necessary to frequently replace them with new ones, and for this reason it should be so arranged that they can be easily and quickly removed from and replaced in the reeds.

The lisle web, being perfectly plain, is similar in general character to the loom web, except that it is made with high grade combed and gassed yarns for the filling in place of cheaper stock used on the loom webs, and is woven with four threads for the binder warp between each strand of rubber, instead of two as in the loom web. The harness draft of the one-half inch lisle web shown at Fig. 7, together with the weave, is shown at Fig. 7A. The construction is as follows: Binder, 36 ends 80/2; gut, 8 ends 40/2; rubber, 10 ends 32s; reed, 21 dent; picks, 78 per inch; stretch, 75 per cent.

It will be seen that all the binder threads operate two up and two down, but change at each pick in rotation, making the repeat every four picks of the loom. In a weave of this character the changes of the harness are distributed uniformly at each pick, thus making it much easier to get uniform conditions on each selvage. It differs from the loom web in this respect, where the alternating light and heavy pick has to be contended with.

Like the loom webs, prominence of the rib over the rubber thread is the main feature aimed at in the general appearance of the fabrics, and therefore everything possible should be done which will emphasize this. The binder warp must be of fine yarns, and the warp must be weighted so as to cut the warp line down sharp and clear up to a point of safety, beingcareful at the same time not to go to excess so as to narrow in the goods or cause undue chafing of the rubber warp. The yarn most generally used for filling is 26-2 comber and gassed high grade stock, of about 15 turns per inch. It should be a well-rounded lofty yarn so as to obtain all the covering property possible. It should be spun with the utmost uniformity, as the slightest irregularity in the yarn will be noticeable in the goods.

The dyeing and bleaching of the yarn used for filling is also of the greatest importance. It is not an unusual occurrence to find otherwise perfect goods made unmarketable as first class by the use of a filling yarn which has not been properly processed. This faulty condition of the yarn may be caused in a variety of ways; such as an irregular boil, poor circulation of liquor in the kier, irregular drying, etc. Even when the color appears to be perfect, poor processing will often prevent the smooth running of the yarn from the shuttle, causing it to drag and thus create irregular and crooked selvages which result in the repeated breaking of the selvage rubber threads and ruin the goods.

The many difficulties of this character which were encountered when skein yarn was more generally used for filling led to the introduction and almost general use of warp yarns for filling purposes, inasmuch as the method of processing the warp yarns gives results which are not nearly so variable. Furthermore the long unbroken runs of thread obtainable by quilling avoid the many knots which are present when using skein yarn. Knots are unsightly and objectionable when appearing on the face of the goods.

Chafed and broken edge rubber threads, however, are not always the result of the conditions named, by any means, but may be caused by a variety of other things. Not infrequently the edge wire may be weaving too long in the web so as not to draw out freely. Sometimes it may be a bent wire that causes the trouble, or it may be the rubber rolling around the wire. Many times defects are caused by the edge wire having cut into the dent, so that it has a file-like effect as the rubber thread passes by in weaving. All these things require looking into, and when trouble comes the cause should be found and not guessed at.

Another plain web which has attained considerable popularity, and which is a kind of intermediate grade between the loom web and the lisle, is what is known as the French web or railroad weave, shown at Fig. 8. In almost all respects the general treatment of this web is the same as already described, and it differs only in the draft, which is shown at Fig. 8A. It allows for the use of a somewhat finer yarn than is generally employed in the loom web, and the draft changes at every two cords, which gives it a peculiar “rowey” appearance from which it derives the name of railroad weave.

There is one feature associated with all these plain webs which it might be well to speak of. The high tension at which it is necessary to work the rubber warp, together with the light weight required on the cotton warp and the crowding together of the picking, creates a tendency for the goods to rebound at the front reed, accompanied by a backward and forward sliding movement when passing over the rod at the breast beam. This movement is liable to polish the goods, which is an objectionable feature. To counteract this it is advisable to let the web pass over a small, felt-covered wood tube, which revolves and responds to the movement of the bounding web. In this way there is no friction to glaze or polish the web and interfere with the bloom of the yarn. The same polish will occur as the goods pass through the press rolls, unless they are felt covered.

The most popular web now made up into men’s garters is what is known as the cable web, shown at Fig. 9. With the pronounced prominence of the two-dent rib, which gives it a character peculiarly different from the plain web, it is well adapted to this class of goods. Simple in appearance, it nevertheless requires special care to manufacture, particularly when we remember that it is not unusual to be required to make a finished stretch of not less than 100 per cent. The harness draft and weave are shown at Fig. 9A. The construction is as follows: Binder, 34 ends 80/2; Gut, 24 ends 20/2; Rubber, 18 ends 28s; Reed, 20 dent; Picks, 80 per inch; Stretch, 100 per cent.

The filling, floating across the wide spaces under which lie the rubber threads in pairs, is very easily thrown out of place, the result of which may be an unsightly seersucker appearance, as shown in Fig. 10, which the process of finishing aggravates rather than corrects.

Trouble may manifest itself by the filling over the ribs opening up and allowing the gut threads to prick through. To prevent this objectionable feature it is necessary to use a good quality of moderately soft yarn for the gut, not necessarily of high grade stock, but a yarn which is uniformly spun and not at all hard or wiry. As these goods are being woven and on full stretch, the gut threads, of course, are perfectly straight and accurate in line, but when contraction takes place, to probably one-half the former length, these heavy threads, which form probably about 25 per cent. of the weight of the entire web, should bend or fold uniformly and dispose of themselves in such a manner as not to appear in any way on the face of the web, snugly housed away in the several pockets or cavities. If the yarn composing these gut threads is spotty or irregularly spun, this uniformity of fold inside the pockets will be broken up and the appearance of the face of the goods is likely to be marred by unsightly specks of cotton pricking through, which can be both seen and felt.

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