TWILLING JACQUARDS
Fig. 116
As has been stated before, one of the drawbacks to a pressure harness is the strain which the warp has to undergo when forming the shed. This necessitates having a good warp, which adds to the cost of the cloth, and in low-class goods this consideration may hinder the sale. Many methods have been adopted for working the ground of the cloth without using a pressure mounting. Some of these are explained under ‘half harness’ and ‘split harness,’ but none of these methods would produce cloth like the pressure harness. A twilling jacquard to act similar to the pressure harness, but without using the front mounting, or by dispensing with the leaves of heddles, was patented by Mr. Shields, of Perth, in 1859. This machine underwent several improvements, and now there are two varieties of it in use, one known as the Irish or Bessbrook machine, being patented by Mr. Barcroft, of the Bessbrook Spinning Company Limited, county Armagh; the other as the Scotch machine, the improvements being made by Mr. Shields and others. The principal difference between the two machines is that the blades or knives of the griffe have a horizontal or sliding motion in the Scotch machine to enable them to get clear of the heads of the hooks, whereas in the Bessbrook machine they turn out of the way or partly revolve. A full description of the Bessbrook machine is here given. [Fig. 116] is a view of the framing of the machine. K is the cylinder, which may be wrought by the swan-neck motion, as shown, but it is better to be wrought by a separate motion from the loom. D is a cord attached to the handle of the shears for reversing the cylinder; E is a brass bushing through which a shaft passes for raising the griffe. The shedding of this machine is exactly the same as that of an ordinary single-acting jacquard. The griffe rises and falls for every shot; the cylinder travels out and in, but does not turn till two or three or whatever number of impressions required are given by each card. To prevent the cylinder turning it is only necessary to raise the shears so that they will not catch it. This is done by means of the tappet A, shown in Figs. 116 and 117. The roller H on the shears rests on the tappet, which is turned by means of the rack wheel, which is fast on it, and the lever L, which is loose on the stud. This lever is pushed backwards and drawn forwards by the rod I, which is connected to an arm, either on the shaft for raising the griffe, or on one for working the cylinder, and the catch on the lever takes a tooth of the ratchet wheel at each draw, so that with four divisions on the tappet, and 12 teeth in the ratchet, three shots would be given to each card. If it is required to work the cylinder the reverse way, it is only necessary to tie the cord D on the end of the shears to a spiral spring made fast to any convenient part of the loom, then the roller C will be acted upon by the underside of the tappet, and the under hook of the shears will turn the cylinder when required. B is a spring acting as a pawl to keep the ratchet from moving backwards, and there is also a spring shown over the catch which moves it forward; both these springs serve to keep the tappet steady. There are two sets of hooks and needles in this machine—the ordinary set for working the harness, as shown at A ([Fig. 118]), and a set of twilling hooks, one row at each side of the machine, which are much stronger than the others. The ends of the twilling hooks are hooked round bars, which pass through the loops at the lower ends of the ordinary hooks, as shown at C ([Fig. 118]). These bars are kept in their places by a grid D, which is between the ordinary hooks and the twilling hooks. Each of the needles of the jacquard is connected with two or more of the ordinary hooks, as shown at A. The twilling hooks have also needles on them, but they are only for the purpose of keeping them in their places, and are not acted upon by the cards. The springs of these needles are on the ends next the cards, or at the back of the faceplate or needle, as shown at E. The centre support for the knives of the griffe is shown at F, with an end view of two knives G G. The ends of the knives enter the griffe frame at each side, so as to allow them to oscillate or partly revolve. This motion is given to them by a set of bars or flat needles, as shown at A ([Fig. 119]). A single needle is given at A1. These needles have each the notch in them over the top edge of two or more of the knives, and are acted upon by a barrel C with studs in it, set to the twill. This barrel rises and falls with the griffe, and is turned from one row of pegs or studs to the next one each time the griffe falls by the head or lantern on it coming down on a finger, as shown at A (Fig 120). B in the same figure is a strong spring to keep the barrel steady and make it turn the correct distance.
Fig. 117
The number of knives in the griffe must be regulated to suit the twill to be put on the cloth; they must be a multiple of the twill, and this to some extent regulates the number of needles that must be in each upright row. For example, an 8-leaf twill may have 16 or 24 knives, which would be twice or three times over the twill. If there are 8 rows of needles to 16 knives, or 16 rows of hooks, that would be 2 hooks to each needle, or if there are 24 rows of hooks there must be 3 hooks to the needle; but if only 2 hooks to the needle are required, there must be 12 rows of needles to 24 rows of hooks. The same principle holds good for a 5-leaf, or any twill. Eight or 12 rows of needles would not be suitable for a 5-leaf twill, neither would 10 rows of needles be suitable for an 8-leaf twill, if the same number of hooks have to be connected with each needle; but 10 rows of needles with 20 rows of hooks or 20 knives will answer for a 5-leaf twill with 2 hooks to the needle, or would answer for an 8-leaf twill with 24 rows of hooks, 4 of the needles to have 3 hooks to each, and 6 of them to have 2 hooks to each.
Fig. 118
Each of the twilling needles, A, [Fig. 119], must be connected with as many of the knives as there are repeats of the twill; thus, for 24 with an 8-leaf twill, the 1st, 9th, and 17th knives would be acted upon by the one needle, and so on with the others.
Now as to the action of the machine. When the pattern card presses upon the needles the griffe begins to rise, and when rising it must lift all the hooks required for the pattern except 1/8th part of them which must be left down (in an 8-leaf twill) to form the binding or texture of the cloth. In addition to this, 1/8th part of the ground warp must be raised for the weft to pass under it and form the ground texture. This is all accomplished by the one rising of the griffe. When the griffe is down, one of the twilling needles, A, [Fig. 119], is pressed back by a peg or stud in the barrel, which causes the knives connected with this needle to turn out of the way of the heads of the hooks, so that when the griffe is rising these knives will pass clear of them, leaving every eighth row of hooks down to form the binding of the raised or pattern warp. In the Scotch machines the knives slide back instead of revolving. As shown at H, [Fig. 118], there are projecting pieces of brass fastened on the knives between the twilling hooks. These hooks stand clear of the knives, but when the latter revolve the projections on them push the hooks forward to the next knife, which lifts them when the griffe is rising. The hooks draw up the bars to which their lower ends are looped, and raise the rows of ordinary hooks through which the bars pass, thus forming the twill on the ground in the same way, but in the reverse direction, that the knives passing clear of the adjoining rows of hooks form the twill on the figure.
Fig. 119
Fig. 120
The working of the texture requires the griffe to fall for every shot, which would be otherwise unnecessary, and the card must come in against the needles each time to push off the hooks that are not to be raised. This causes wear and tear, which cannot be avoided with this machine, but they work very well, though they are not by any means perfect. There is a good deal of friction on the needles, which causes them to wear quickly; but being so much easier on the warp than the pressure harness, and more easily managed, they are extensively used for large patterns in the fine linen damask trade. They will not make so firm a cloth as the pressure harness, and have the objection that all twills formed with the harness have when there is a gathered tie—viz. that a portion of the cloth will have the twill running in one direction and a portion in the reverse direction.
Like all single-acting jacquards, these machines have no counterpoise in themselves, and being very heavy require one added to assist the loom to raise them. Sometimes this is accomplished by means of a carriage spring placed on a beam or on the top rail of the loom frame; and an arm from the shaft, which raises the griffe resting on the spring, will form a sufficient counterpoise, the spring being made as strong as is required for the purpose. Unless the springs, which are made similar to those used for carriages, are nicely tempered, and the different pieces made so as to slide freely on each other, they are liable to snap when the loom is running quickly. The griffe is generally driven from the fly-wheel on the crankshaft in the same manner as for ordinary single-acting jacquards. It is, however, a better plan to drive it from a crank on a stud wheel gearing into the tappet-shaft wheel. This does away with the necessity for a counterpoise unless the machinery is very heavy, in which case a few strong spiral springs will suffice. The horizontal shaft for raising the griffe, or griffes if two or more machines are used, must be very strong, so as not to twist with the tortuous strain, which is very great. Three of these machines, with 500 or 600 needles to each, are required for tablecloth mountings when tied up for centred patterns—one machine to work the border, one the centre, and one the portion between the border and the centre; or two machines to work the double portion, and one the single portion. [Fig. 121] gives a view of a mounting tied up in this way, Nos. 1 and 2 machines being double mounting and No. 3 single.
Fig. 121
The Karl Wein Jacquard.—This machine is a twilling jacquard on the same principle as that last described, but performs its work in a more scientific manner. It was patented by Messrs. J. Tschörner and K. Wein, Kesmark, Hungary, and was first introduced into this country at the Glasgow Exhibition of 1888.
The following is a description of the machine exhibited there: The principal feature of this machine is perhaps that each knife acts independently in a grid, and is wrought by a tappet at the side of the loom, so that any row of hooks can be raised or lowered at pleasure, and this without any change of card. [Fig. 122] gives an end view of the framing, showing the upper and lower grids in which the knives or lifters slide. An end view of four of the lifters is given at A, 1 and 3 belonging to the top set, which work in the upper grid, and 2 and 4 to the bottom set, which work in the lower grid.
Fig. 122
A perspective view of eight of these lifters is given at B C, [Fig. 123], with upright slide bars D attached to them, which slide in the rack or frame E. These bars are for the purpose of making the lifters rise steadily and horizontally, as (which may be seen) they are not all lifted at their centre. Only one connection is fair in the centre, which would no doubt be an objection with a heavy harness to lift; but this arrangement is made to suit for the machine sitting across the loom, for a London tie, and some method of making vertical connections from the levers to the lifters is necessary. The above does very well for a narrow harness if light.
Fig. 123
Fig. 124
If the machine was fixed on the loom for a Norwich tie, or with the cards to hang over the back, then the connections from the levers might all be at the centres of the lifters and the bars D would only be required to steady them. The levers for raising the lifters are shown at F, with their fulcrum at I. G is a spring, one of which is attached to each lever to keep it down, as the tappet has not a positive rising and sinking motion, only raising the levers and allowing their own weight and the draw of the springs to recover them. One of the connecting rods from the lever to the tappet is shown at I. [Fig. 124] gives the principle of this tappet. A is the lever or treadle with its fulcrum at A; the connecting rod B connects the point of it to one of the top levers F ([Fig. 123]), and C is a bowl at the other end of it which travels on the tappet plate D. The tappet is made up of 17 plates struck to suit; 16 of these are for working the lifters and 1 for the cylinder; it sits at the side of the loom like a Woodcroft tappet. For an 8-end satin twill 16 levers are required, 8 for the bottom set of lifters and 8 for the top set. Fig. 123a shows two lifters B1 and C1 with hooks and needles. A hook and a needle on a larger scale are shown in [Fig. 125]. The hooks are flat pieces of iron cut to the shape shown, with small projecting pieces, as a, riveted to them, by which they can rest on the bottom lifting knives, as at C1 (Fig. 123a), so that when any of these knives are lifted a row of hooks will be raised by them. As before explained in reference to the Bessbrook machine, it is necessary when the pattern card presses on the needles for all the knives except one to act, and also for one of the bottom lifters to rise to form the texture of the cloth; the same must be in this machine, and can easily be regulated by the tappet, which should hold up the warp required for the pattern and work the ground texture as well. This is done in the following manner: Suppose there are 16 lifters, 8 top and 8 bottom ones. When the card presses on the needles, 7 of the top and 1 of the bottom lifters should be raised by the tappet, and the top lifter, which is left down, should be raised so far as to catch the heads of those hooks in the row belonging to it that are not pushed back by the card. For the next shot this lifter is raised and another one let down, but it is not let down far enough for the hooks to get off it, stopping at the same height that the first one was raised to, which is easily regulated by the tappet. If there are 3 shots to the card, another similar change takes place; then for the fourth shot all the lifters are dropped, the cylinder presses in, and all but one of the top lifters and one of the lower ones are again raised, and the twill proceeded with as before. It will thus be seen that the shedding for the twill acts as in a double-acting jacquard, but the lift at the change of card is similar to that of a single-acting jacquard. Of course the tappet must be struck to change the lifters according to the twill required on the cloth. In the Bessbrook machine there could be 16, 24, or 32 rows of hooks to 8 rows of needles by having 2, 3, or 4 hooks to each needle, or the number of hooks to each needle might vary and any number of needles might be used. There must be a knife for each row of hooks, but all the knives belong to the one griffe. In the Karl Wein machine there must be 2 lifters for each row of hooks, and 16 of them are enough to have for convenience. In the machine exhibited, 16 hooks, or 2 rows of 8, were attached to 6 needles, 4 needles having 3 hooks to each and 2 needles 2 hooks to each, as shown at B ([Fig. 125]), the thick vertical lines representing 1 row of hooks, and the thin lines the next row. There were 6 rows of needles in the needle board, and the point of each needle was cranked as shown at C; each row of holes for the needles in the needle board, or face-plate, stood between 2 rows of hooks: the first 3 needles were connected with 1 row of hooks and the second 3 with the next row, the cranks of the first and second set of needles being turned in the opposite direction so as to enable them to fall in with the rows of hooks. Of course there might as well have been 8 rows of needles with 2 hooks to each, or 4 needles to each row of hooks.
Fig. 125
If necessary to use more than one machine, some arrangement would require to be made for lifting them. It might be done by using a double set of levers with connecting rods similar to those used for twilling looms.
The twilling of the ground might be wrought by a griffe and hooks as in the Bessbrook machine, thus doing away with seven treadles and seven tappet plates, but this would make the twilling a single-acting shedding motion.
Since this was written the machine has been altered so as to make it more suitable to the requirements of the work in this country, but does not appear to gain favour, and this class of weaving is not very extensively used.
CHAPTER VII
GAUZE
The principle of weaving gauze with shafts and healds applies equally to making it with a harness, though perhaps the latter is simpler, as there is not the same trouble in the arranging of drafts; and, in intricate work, the number of doup leaves required for shaft mountings adds considerably to the trouble of the weaver and tackler.
The simplest, or in any case the most ready, method of weaving gauze in a harness, is to use an ordinary harness, and form the gauze by means of one or more doups and standards in front of it. Suppose we have have a 400 machine with the harness tied up in simple repeats of 400; any desired pattern can be put upon the cloth to the extent of 400 hooks of the jacquard as in ordinary harness work, but it cannot be made of any texture desired—it must be made to suit the working of the doups in front of the harness. If the open work is to be a plain gauze with one shot into each shed, then the pattern must be plain cloth, as the doup standard must be raised and sunk alternately for each shot; but any desired form or figure can be made in plain texture on the 400 hooks, and the cloth will consist of a plain figure on a gauze ground; or it might as well be a gauze figure on a plain ground.
Those not acquainted with figured gauze work, have considerable difficulty in understanding how to make plain or gauze as required on the cloth.
It is easy to understand that working the harness without the doups can make plain cloth, and also that working the doups and standards, and portion of the harness, for alternate shots, can make gauze; but the difficulty is to thoroughly comprehend how, when working gauze, to neutralise the crossing of that portion of the warp that is to form the plain figure. There are two ways of neutralising the crossing effect of the doups on any thread or number of threads that may be required for the figure: first, by not raising the mail or mails carrying the crossing threads, or threads in the doups, but forming the plain by raising the mails carrying the threads not in the doups, alternately with the doup standard; and, secondly, if the threads not in the doups are raised along with the doup standard, no crossing can take place; but this would not suit for working plain cloth, as these mails must be down when the doup standard is up in order to form plain cloth.
Fig. 126
If a different gauze is required, say one with 2 shots into each shed, or between the crossings, then the solid texture might be a rib or mat; or if it suited the pattern, as in the case of dice work, two doups could be employed, so that one could rest when the other is working the gauze. [Fig. 126] is a plain gauze and plain texture, common dice pattern, which could be wrought with shafts, but shows the principle of working with the harness as well. This could be wrought with one doup in front of the harness. To work the dice A the mails carrying the threads not in the doups would be raised alternately with the doup standard, and thus form plain cloth; and at the same time, to make the dice B a gauze, the mails carrying the threads in the doups would be wrought alternately with the doup standard. For the dices C and D, this would be reversed. In case of the gauze having to be made with, say, 3 shots into each shed, and 2 threads twisting round 2 to give openness of texture, it will be seen that it could only be wrought with one doup, provided 3 shots went to each shed of the solid dice, as the doup would require to be up for 3 shots in succession, and down for the same. If plain cloth were required it would be necessary to have a doup and standard for each dice, so that one could remain down when the other is raised for gauzing; this would allow the harness to work any texture on the solid dice, the doup of which is not gauzing. If it were required to work a diagonal stripe of plain and gauze, as shown in [Fig. 127], with 2 weft shots coming in between each crossing of the gauze, 6 doups would be required in front of the harness, whereas if only one shot came between the crossings only one doup would be required. It will be seen that there are 6 splitfuls of warp to one repeat of the pattern, and that the change from the plain to the gauze is at a different time for each; therefore, on account of the doup standards having to be raised for 2 shots in succession when a portion of the cloth is plain texture, it is necessary for each splitful of warp to have its own doup so that it can be crossed without interfering with the plain texture in the other portion of the cloth.
Fig. 127
This pattern would be better suited for a shaft mounting than for a harness with doups in front, but could be wrought with a gauze harness more easily than with either. The advantage of using a harness with doups in front, in this case, over a shaft mounting, would be that the plain stripe could be figured if desired, and the gauze stripe might go in steps of two or three splitfuls alike, which would give much bolder stripes.
When more than one or two sets of doups would be required to be used in front of a harness, it is advisable to adopt a true gauze harness, as the doup shafts come in the way of the weaver. A gauze harness has the doups in the harness, so that they can be lifted independently, which admits of indiscriminate figuring on either the gauze or solid portion of the cloth.
When using doups in front of the harness it is not necessary that the plain or solid cloth should be all a plain or unfigured texture; any suitable warp figure may be formed on the plain by the harness, but weft figures cannot be made on the upper side of the cloth, because, though the harness can be raised for any number of shots in succession to form a figure by the warp, having it sunk would not in the same way form a weft figure, as in crossing the gauze a portion of the yarn would be raised by the doup standard, which cannot be prevented, unless by having more doups than one. A harness with doups in front is better suited for working stripes than any other class of work, and it is in this class of work that gauze can be made most effective.
When figuring with gauze, unless several shots are thrown into each shed, or between the crossings of the gauze threads, and 3 or more warp threads are twisted together, the openness of the texture is not sufficient to make a good contrast between the plain and gauze unless the fabric is very light; and even with 2 threads round 2, and throwing 4 to 6 shots into each twist, the contrast is not so great as might be desired when the cloth is heavy. A portion of the weft, say every second or third shot, might be made to pass either over or under the gauzed texture and interwoven only with the solid portion of the cloth, the flushed or loose weft to be cropped off afterwards. In stripes, not only can this be done, but the warp may be set much thinner or wider in the reed for the gauze: say every second or third split may be left empty; or it may be of a different description of yarn—a fancy twist if desired, or in threads of different colours. A fancy stripe with three threads to the split in a reed, set 30 splits per inch, and every second split of the gauze portion left empty, makes a very effective pattern for fine work, with say 80 picks per inch; or 120 picks might be used, and every third or fourth one not wrought into the gauze, but flushed over to be cut off afterwards. There might be 2 thick threads or 4 finer ones to each split of the gauze, and 4 to 6 shots into each crossing, this, of course, to be regulated to suit circumstances and taste; one thing must, however, be remembered—viz. that when made too bold or open the warp ribs are liable to slide on the weft, and this is the chief defect in gauze when made open, especially when a smooth, clean yarn, as linen, is used.
Fig. 128
Fig. 129
Fig. 130
When working stripes, any pattern, or any texture or style of cloth, whether single, double, or pile work, may be used for the solid stripes, or the whole cloth may consist of stripes made of combinations of gauze and solid textures. One set of stripes may be wrought quite independently of the other by having the yarn on separate beams, and when only one set of stripes is gauzed, the others are not drawn into the doup heddles, so are quite independent of them. The doup heddles may be spaced or otherwise as desired. When working with doups in front of the harness, there must be a slackener for the crossing threads for each doup standard, same as for heddle work. Figs. 128, 129, and 130 show some of the methods of slackening in use. In Figs. 128 and 129, A is the yarn beam, B the back rail, C and D the vibrating bars or slackeners, C acts as a fulcrum; and in [Fig. 128] the bar D presses the crossing yarn down and is raised by the tappet E, which may be either above or below a lever on the end of the bar C, a spring on the lever regulating it, to hold it against the tappet. In [Fig. 129] the bar D is sunk to relieve the crossing yarn, by drawing up the cord G, which is attached to the jacquard or dobby, the spring H holding the lever E down when it is relieved. [Fig. 130] is similar to [Fig. 129], but for two doups; it is shown both in perspective and in end view, and will be clearly understood. C and D must be set at such a distance above each other as will permit of the traverse of D without C being moved. Two or more shafts of heddles might also be used which could hold the crossing yarn either up or down, same as the bars, till they are acted on by the jacquard or by a tappet.
Fig. 131
Fig. 132
Designing.—When designing a pattern for gauze, with doups in front of the harness, it is only necessary to set off a few hooks of the jacquard to work the doups and slackener, and design the fancy portion on the remaining hooks; or if the gauze and slackener are wrought with tappets the full jacquard will be available for the figured portion, the same as if no gauze were being made. If the doups and slackener are to be wrought by the jacquard the pattern can be painted on the remaining hooks, and the dots for working these can be added afterwards, agreeably to the texture of the gauze required. The doup standard and slackener should act together, and the doup or half leaf should rise when the harness carrying the crossing threads rises. If the doup standard is to be raised every second shot, as is required when plain cloth has to be wrought with one doup, it might be wrought by a tappet, and the doup or loose heald might be raised by the machine for every shot, as it must rise with its standard as well as when the harness raises any of the yarn drawn into the doup. The doup shaft is best held down by a light spring. Indiarubber about 3/16 or 1/4 in. in diameter suits very well. One spring at each side of either one or two ply of this should be sufficient. If the number of rows in the harness is such that it will correspond with the number of threads to be twisted together, or be a multiple of them, it will be all the more convenient, though it is not necessary for it to be so. For instance, if 1 thread is twisted round 1, =2, an 8-row harness would give 4 repeats of this in each row; but if 1 thread were twisted round 2, =3, then 1 row of the harness would give 2 repeats, or hold 2 splitfuls of warp and 2 threads over, so that another thread would have to be taken from the back of the next row. For this a 6-row harness would be more convenient, which could be got by leaving 2 rows of the machine idle, and designing the pattern on 6-row paper, or ruling 8-row paper to 6-row after the design is painted. To work fancy textures with gauze by means of a harness with doups in front, both must be arranged to suit each other, unless a large number of doups be employed. For instance, a 2-and-2 twill could be wrought with 1 doup leaf in front of the harness by making 1 thread of the gauze twist round 3, and throwing 2 shots into each crossing, as shown in [Fig. 131]. If 1 thread were to be twisted round 1 with a 2-and-2 twill, and 2 shots to the gauze crossing, 2 doup leaves would be required, as shown in [Fig. 132]. A 4-thread fancy twill can be wrought with 1 doup, as shown in [Fig. 133], 1 thread twisting round 3 and 4 shots into each crossing of the gauze. Satins or regular twills are more difficult to work, unless by making an irregular gauze. Take a 5-end satin, which has the threads over 4 and under 1. The gauze might have 4 shots and 1 shot into each crossing alternately, and be easily wrought with 1 doup; but if 2 or 3 shots had to go to each crossing it would be different, as the doup would require to sink for 1 shot out of 5, in order to let the threads drawn into it bind in the twilled portion of the cloth, or otherwise the binding would have to take place on these threads when the doup is down, which it could do if it suited otherwise. But it must be remembered that when solid cloth and gauze are working together, the former is made by raising the doup standard and those mails which carry the threads that are not drawn into the doup, leaving stationary the mails carrying the crossing threads, except where gauze is being made; therefore, in working a 5-end satin, if the doup held up any of the threads for, say, 3 shots, and then sank for 3, there would be no way of holding up these threads in the twill portion to make them pass over 4 shots, as a 5-end satin must do, for if the harness twines carrying these threads are raised, they will cause a cross to be made instead of completing the twill. Patterns of this description should all be wrought in a gauze harness. In the figures given the gauze crossings are represented by dotted lines where they are raised by the harness, for sake of distinction.
Fig. 133