Chapter VII: Card Clothing, Grinding, and Stripping

(154) As was shown in the preceding chapter, the cylinder, doffer rollers, &c., of carding engines are covered with a wire clothing, the proper construction of which is of high importance. It forms a sort of wire brush, in which the points are fixed in a special matrix, or “foundation,” as it is called. Formerly it was the universal practice to make the foundation of leather, but various considerations have led to its abandonment, except in the case of woollen cards where an oily or greasy material requires dealing with. In lieu of leather three specially prepared materials are now employed, one being what is called a cotton-wool-cotton, another cotton, and the third a natural rubber foundation. The first of these consists of two thicknesses of cotton cloth specially woven with a wool fabric cemented between them. The rubber foundation consists of a thin sheet of natural india-rubber imposed upon and securely cemented to a back of cotton and wool. Great care is taken that the india-rubber shall be pure, and in some cases the manufacturers of card clothing also produce their rubber sheets. The object aimed at in each case is to obtain a foundation which shall be strong enough to hold the wires securely, and at the same time be possessed of some elasticity, so as to aid the wires to recover their position when bent during work.

(155) It was at one time the practice to make the cards in sheets four inches wide, and long enough to cover the width of the machine, but this has been abandoned in favour of a plan by which they are made in long strips or “fillets.” These are long enough to completely cover the cylinder, on which they are wound in a way which will be hereafter described. Having obtained the fillet for the foundation, the next step is to introduce the wires. These are produced from a reel of specially drawn steel wire, which is frequently hardened and tempered by a continuous process. It is essential in conducting the latter that the wire should be free from scale, and, in the great majority of cases, this is attained. In fixing the wires into the foundation the preliminary step is to cut off from the wire carried on a reel a sufficient length, and bend it up into the form of a right angled staple, having two parallel arms joined by the third side. The extremities of these arms constitute two of the points to be fixed in the foundation, so that it will be seen these are always introduced in pairs, and not singly. In order to facilitate their passage through the foundation, two holes, pitched to correspond with the distance of the two points apart, are pierced in it, and immediately on the withdrawal of the piercer the staple is pushed in, and forced up to its place. Almost simultaneously with this operation it is set—that is, is bent to an angle as shown in Fig. 85. After one pair of wire points are fixed the fillet is traversed, so as to introduce another pair at the required distance from the last one. When the width of the fillet has been filled with teeth it is moved a little lengthways, far enough to begin the next line, and the direction of the carriage is reversed. It is highly important that the wire points should be set equidistant over the whole of the surface, so that when the cylinder is clothed, the regularity of the carding points will be unvarying. The whole of the operations of feeding, cutting, and bending the wire, piercing the fillet, forcing in the teeth, traversing and reversing the carriage, and traversing the fillet longitudinally, are automatically performed by a machine of great ingenuity, originally invented by Mr. J. C. Dyer. It is one of the best examples in the whole range of mechanics of the power of the cam, and works with great rapidity, being capable of fixing over 300 pairs of wire points per minute.

(156) The teeth can be set in the foundation in three ways—either plain, twilled, or ribbed, these settings being shown in Fig. 76, the dots representing the wire points, the back of the teeth being shown by the dotted lines. In the first case the teeth are in straight lines; in the second they are, as the name implies, set diagonally; while in the third they are in straight lines, but set so that they are in sets of three, each of which overlaps its predecessor. Generally, plain setting is very little used, fillets being commonly made ribbed, except in the case of the flat covering, which, when mild steel wire is employed, is usually twilled. In manufacturing cards for covering the flats it is common to commence with a large sheet equal in width to the length of the flat. The teeth are then set for a space equal to the width of the flat, when the sheet is rapidly traversed longitudinally until the point for starting a new flat strip is reached. These strips are cut out of the sheet, and thus leave the necessary margins for fastening to the flat. In America twilled setting is preferred, but, in this country, it is objected that spaces are left between each lap when fixed on the cylinder, which is very objectionable. This fault does not occur where ribbed fillets are used, and it is now almost the universal practice to use this setting for cylinder and doffing coverings. However the teeth are set in this respect, they vary also in their distance from each other, and this variation depends on the “counts” of the wire. This phrase is used to indicate the fineness of the pitch of the wire teeth, and the method of counting is based on the number of teeth in the width of the sheets formerly made. Thus, if there were 100 teeth in a sheet four inches wide, the counts were said to be 100’s, the same rule being applied to-day. Longitudinally, the pitch of the teeth was ten “crowns,” or points, to the inch, this being also retained as a standard of measurement. In this way it is possible, by knowing the counts of wire, to calculate easily the number of teeth per square inch. Thus, in the instance named, there would be 100 × 10 = 1,000 teeth in the four inches of width by one inch in length, which is equal to 250 teeth in every square inch.

(157) In clothing the various parts of the machine experience has shown that there can be wise variations made in the kind used. Every spinner has ideas of his own, and as there is a wide difference in the class of material treated no rule can be laid down. In clothing the licker-in, a tooth which is known as the “Garnett” is universally used. An illustration of this is given, in full size, in Fig. 77, the finer tooth shown being used when no undercasings are fitted, and the coarser when they are. It will be noticed that the former is a little more hooked than the latter, which enables it to carry round the cotton without flinging it below the licker-in. The presence of an undercasing obviates much of the necessity for this carrying power, and the tooth is only required to beat off the cotton from the lap and thus throw down the motes, etc. In covering the cylinders of roller carding engines, where medium counts of yarn are being spun, clothing with 90’s to 100’s wire is used, the rollers being covered with the same counts, the clearers with a finer wire, and the doffers from 100’s to 120’s. These, of course, are sizes which are commonly employed, and indicate the usual limits, but, as has been observed, practice varies considerably in this respect. In revolving flat carding engines the cylinders are covered with 110’s, and doffers and flats with 120’s for medium counts of yarn. It may be generally stated that the finer the counts of yarn spun, all other things being equal, the finer the wire clothing employed; but it can only be settled by practice what are the best counts to use in any individual case.

(158) As has been observed, the wires are, in the process of setting, bent to an angle, or, rather, a double angle, after leaving the foundation. A reference to Fig. 85 will show that they leave the foundation at an angle in one direction, and afterwards bend sharply in the opposite direction. The diagram given in Fig. 78 illustrates this construction. The foundation is shown by the letter =D=, to which the line =A B= is perpendicular, leaving the upper surface of =D= at =E=. The tooth is indicated by the line =A C E B^{1}=, and it will be noticed that the point of the tooth at =A= is perpendicular to the point =E= where it leaves the foundation. This is the correct setting, or nearly so, for the following reason. Some makers, it may be stated, prefer to let the point =A= be a little behind the perpendicular line =A E=. In working, the wire point is pressed by the material and is sprung backward, in which case it—when set as shown—will radiate round =E= and move in the circle shown by the letters =F A G=. Thus, if another set of wire points are imposed upon the lower ones, the flexure of the latter, in either direction, is followed by their recession from the former, and no danger exists of any interlocking, which, if it occurs, is injurious to both sets of teeth. As the relative positions of the upper and lower teeth are of the character described in the previous chapter, the adoption of the method of setting the teeth indicated is of considerable importance. It is, of course, possible to vary the angularity or “keen” as desired, and the more acute the angle =E C A= the more fibre caught and retained. Thus the proportion of waste made in a machine during work is largely dependent on the angular setting of the wires, and this is a point specially worth noting. The essential element is the approximate perpendicularity of the point =A= of the wire to that (=E=) where it leaves the foundation.

(159) With regard to the shape of the tooth a good deal can be said. Ideal carding would be obtained by the use of fine needle points closely set, as will be seen in dealing with the combing machine, but it is manifestly impossible to employ teeth of this description in a carding engine. Although they might be inserted and used in new clothing, as soon as they became blunt it would be impossible to restore their points owing to their position in the clothing. But the principle remains; and, failing the employment of needle points, the attention of makers has been directed to the production of a wire which will present to the cotton what is practically a needle—or more accurately—a knife edge, which can easily be renewed after wear. To Messrs. Ashworth Brothers belongs undoubtedly the credit of this important step, which brought in its train many changes in the general construction of the machine. They use a wire which is round in section, but which they grind at the side so that above the foundation it becomes oblong, thus presenting a sharp edge to the fibres while preserving all the necessary strength in the portion fixed in the foundation. Various other sections have been employed, such as double convex, triangular, and oblong, and by a special system of grinding the same kind of edge is produced. The teeth when fixed in the fillets are ground on their edges by thin emery disc wheels formed with bevelled edges, which pass between the teeth and grind them to a sharp edge. A pair of teeth of this character, magnified 13 times, are shown in Fig. 79, which is from a photograph lent by Messrs. J. Whiteley and Sons. It will be noticed that the line of the tooth is gradually tapered until the point, which assumes very nearly the character of a needle point, is reached.

(160) The question as to how far this “plough” grinding is a good thing is one which it is worth while dealing with at length. It is undoubtedly true that steel wire carefully hardened and tempered will, under equal conditions, wear longer than a softer variety, but it is sometimes argued that the advantage thus derived is counterbalanced by the grave faults often existing after a surface of this kind has been side ground. The idea of a needle point is the right one, but it is worse than useless unless the wire remains smooth. There are two evils to be guarded against—the barbing or hooking of the wire points and the striation of the sides of the teeth. Both of these faults are often produced in side grinding, this fact having been fully established by a number of investigations made by various observers.

(161) It is apparent that the abrasion of a wire surface by means of an emery wheel is sure to produce a certain degree of roughness. If any student of the subject will take the trouble to examine newly-ground clothing by the aid of a glass magnifying from 10 to 20 times, the scratches caused by the rotation of the emery wheel are easily seen. It requires very little reflection to show that this is sure to be detrimental. Mr. B. A. Dobson, of Bolton, who has gone very extensively into the subject, published with an address delivered by him in America an interesting series of photographic representations of side ground teeth. These were enlarged a number of times, and were then reproduced. Striated sides and barbed points are common in this series. Now the inevitable effect of such a tooth is to break or destroy the fibre, or remove from its surface a portion of the waxy covering. This leads to an increased waste in the subsequent processes, although that produced in the carding machine may be less. It is hardly worth while discussing the point further, but there is one fact which speaks volumes as to the general opinion on the subject. It is agreed that the treatment of the teeth by those of a wire burnishing brush has a very beneficial effect upon them, and the carding afterwards carried out is much cleaner and better. This is one reason why the brush used to strip the flats is occasionally made of wire. As the action of a burnisher is to remove scratches previously made, its use is a confession of their existence.

(162) The roughening of the wire teeth is not, however, inevitable. In Fig. 80 is shown a side view of a plough ground tooth magnified 32 diameters. In this the striations are most marked, and there needs no comment to demonstrate their existence. In Fig. 81 a similar tooth ground in a special manner, and similarly enlarged, is shown. The surface of this is so much smoother than the other, that practically it is perfect. At any rate it is so much better than the one shown in Fig. 80, which is ground in the usual way, as to be an entirely different article. Both of these photographs are supplied by Messrs. John Whiteley and Sons, and the system of grinding by which the tooth shown in Fig. 81 was obtained, is now in regular use by them. The objection is not to needle or chisel shaped teeth side ground, but to these plus striation, and if the addition can be removed, many of the objections rightly entertained will be obviated.

(163) When the clothing has worn it is desirable to grind it frequently but lightly. The practice of allowing the tooth to become very blunt prior to grinding is very objectionable, as it leads to heavy grinding and there is a danger of hooked teeth. It is impossible to state a general rule on the subject, as the periods of grinding depend so largely on the class of cotton treated, but it is better to give a light grinding to the wire every few weeks.

(164) In the last chapter, in paragraph 107, it is pointed out that the cylinder is drilled with a number of holes arranged in straight lines across its periphery, in which wooden plugs are tightly driven. These are intended to aid in fastening on the fillets, and before clothing the cylinder or doffer, it is desirable to mark the centre of each line of holes on each edge, and to set out the position of each hole in one line on a staff. In this way, when the surface is covered, the exact position of each plug can be ascertained, and the tack inserted without damaging the wire. As the cylinder surface is quite level, the fillets are in some cases wrapped on the bare face, but there is some danger of the clothing slipping, especially if made with a rubber foundation. To obviate this serious defect, the surface of the cylinder is covered with a specially woven cotton cloth, or with brown paper, the former being preferable. This covering is put on without any puckers or creases—a very essential thing—and is attached to the cylinder by a special kind of cement or paste. On a surface prepared in this manner rubber foundations will not slip in working. With fillets in which the foundation is a woollen one, these precautions are not necessary. If it is intended to employ rubber foundations, great care must be taken before proceeding to clothe the cylinder. The fillets must be kept in a room heated to the same, or a little higher, temperature than the card room in which they have to work. This treatment causes the fillet to expand to a certain extent, and should be continued for some hours prior to their being used. Thus when the fillets are fixed in their position they do not expand as they would do if kept in a cold room before being used. Woollen foundations do not expand by heat, and can, therefore, be used and fixed without the preparation named. For this reason they are suitable for employment in places where the direct sunlight can fall on them. Oil being detrimental to india-rubber, fillets with that foundation should never be used where oil is likely to fall on them. A certain disintegration of rubber foundations occurs in some cases in hot climates, but they are largely used in England.

(165) Having prepared the fillets for wrapping on, the operation is completed. Formerly they were wound on manually, but this is now almost invariably done automatically by a machine made by Messrs. J. Whiteley and Sons, which is illustrated in Fig. 82. One end of the fillet is securely fixed, and the cylinder is then started. The cross slide =K= is fixed on the frame of the machine, or on a special frame if preferred, when the doffers are being clothed, and the apparatus is then ready for work. On the slide =K= a carriage is fitted which is traversed by a screw, on the end of which is a chain wheel =L=, by means of which the necessary movement can be given from the chain-pulley =O= automatically, or it can be manually given by the handle =R=. The carriage bears a drum mounted on a cradle hinged to the carriage. The angular position of the drum is regulated by the tension screw, and the tension put upon the fillet, in pounds, is registered by a finger moving over a graduated scale. The card fillet is taken from the basket through the trough =D=, thence over the drum, from which it is taken to the cylinder. The cylinder is revolved by means of the handle =R=, and the card clothing is slowly wrapped on, the traverse of the carriage being arranged to be at the required speed. In lieu of the drum Messrs. Dronsfield Brothers use a stepped cone, which gives a similar result. Thus, cylinder fillets, when made of hardened and tempered wire, can be wound under a tension of 270lbs., while doffer fillets of the same quality only require one of 175lbs., and for roller fillets, which are only 1 inch wide, 120lbs. is sufficient. What is required is to so wrap the fillets that, without straining them, they adhere closely to the surface of the cylinder or doffer; and do not, after working, rise in places or “blister,” as it is called. After the cylinder is covered the fillet is fastened at its free end, and is then allowed to rest for a few hours, so that it adjusts itself throughout its length. It is necessary to shape the fillet at each end so that, when wound, no break in the carding surface occurs; and, for this purpose, it is usually cut to a shape which permits the first and second coils and the last two to lie close together. It is then tacked on in the way previously described, a special tool being used to drive the tack and avoid damaging the wire.

(166) In fastening the clothing upon the flats several methods are pursued. A reference to Fig. 83 shows two of these. In =A=, which is 2 inches wide, and =B=, which is 1-3/8 inches wide, the edges of the flats are drilled with small holes, and the strip of clothing is similarly punched. One side of the strip is then fastened to the flat by means of lead rivets, and it is then drawn tight along its whole length by a special clip. The other edge is, while the strip is held in tension, riveted firmly in a similar manner. A machine for this purpose, made by Messrs. Dronsfield Brothers, is shown in Fig. 84. Another method is one originated by Messrs. Ashworth Brothers, and is shown in =C= and =D=. In this case the strip is attached by means of wire stitching, the flat being sawn at its edge at regular intervals, as is very clearly shown. A third plan is illustrated in Figs. 85 and 86 in partial perspective and transverse section, this being made by Messrs. John Whiteley and Sons. A clip is passed through the clothing and flat, and is then clenched, as shown separately in Fig. 87. The strip of clothing is then drawn tight, and the second clip fixed in the same way. This method is rapid and effective, and possesses one important advantage. By it the margins of the flat strip are protected from being frayed by the revolving brush used to clean them.

(167) In dealing with the construction of the flats it has been shown that there is a movement towards the use of shorter ones, for the reason that it is felt to be desirable to prevent any deflection by having a stiff flat. Upon this point the consideration of the advantages of various systems of fastening the clothing largely turns. It is quite clear that any removal of metal, either by drilling or sawing, is likely to weaken the flat. It is, however, not so readily seen which is the most weakening, but actual experiments show that wire sewing is so. Mr. B. A. Dobson, of Bolton, has made a series of tests of flats, both drilled and sewn, to ascertain the deflection during working and grinding positions, and the side deflection. These establish very clearly the superior strength of the riveted flat, which is very considerable. For instance, a flat 45-5/8 inches long by 1-3/8 inches wide, with the same thickness in flat and web, gave the following deflections when loaded with a 1lb. and 2lbs. weight respectively. Unclothed, sawn for wire sewing: 1st, when face up, 1/380th and 1/200th inch; 2nd, when on its side, 1/330th and 1/166th inch; and, 3rd, when face downwards, 1/660th and 1/400th inch. Unclothed, drilled for rivets, the deflections in the three positions named were as follows: 1st, 1/1000th and 1/500th inch; 2nd, 1/400th and 1/275th inch; and, 3rd, 1/875th and 1/400th inch. The reason for this is not far to seek. The riveted flat has throughout its length an unbroken metallic surface along its edge, while the sewn flat is broken at intervals to permit the passage of the wire. For the reasons given in paragraph 118, the difference between 1/660th and 1/875th inch is material, especially when the settings of the flats are supposed to be regulated to the 1/1000th inch.

(168) In Fig 88 is illustrated a plan by which the necessity for piercing the flat either with holes or nicks is entirely obviated. This is patented by Mr. Tweedale, manager for Messrs. Howard and Bullough, and consists in the employment of a metallic clip, which grips the clothing at one side, and is bent round and under a small rib on the underside of the flat. The clip is closed by means of a special machine, which runs rapidly along the flat, the two sides being gripped simultaneously, and the fillet stretched by the same machine and at the same time. With this construction the maximum strength of the flat is preserved throughout all its positions and under all working pressures. A similar arrangement is used by Messrs. Ashworth Brothers, but the shape and construction of the clip and the method of fixing slightly varies from that described. It is to be noted, however, that the width of the flat strip must be rather less in each case than that of the flat, and that the strip must in consequence be stretched so as to cover the surface. It is essential that the clips shall be fixed so as to be in contact with the planed edge of the flat throughout its entire length. The edges of the flats ought to be quite straight, especially if they are closely pitched, as otherwise they would come into contact in places. If, therefore, the clips referred to are not pressed closely against the sides of the flats throughout their entire length the danger of touching is increased.

(169) Messrs. Platt Brothers and Company have recently devised a fastening of tinned wire, which is bent up by special machinery so as to form a continuous series of staples, the pitch of the points of which is about 1/2 inch. The staples are connected at the points, so that a length can be produced sufficient for fastening any flat. Holes are drilled in the flat through which the staples are pushed, and are pressed downwards and held. While in that position the points are clenched similarly to Messrs. Whiteley’s clip, and the clothing thus secured. This arrangement is practically a system of sewing without the disadvantage arising from the sawing of the edge of the flat. A strength equal to a riveted flat is obtained, with the advantage of a continuous grip along the flat strip. All these arrangements, however, imply the use of special machines to fix them, which is a condition not always attainable in a mill. For these reasons, where it is difficult to return the flats to a machinist for re-clothing, the use of rivets is most desirable.

(170) No less important than the proper fixing of the clothing in position is the operation of grinding it before starting work and after the points have worn. The licker-in is not ground, as the teeth do not require it, and their shape is such that grinding is impracticable. The cylinder is ground in position, and the question as to which is the correct method is one about which there is a good deal of controversy. In theory it is quite true that the periphery of a cylinder revolving, say, 180 times per minute, will tend to follow a path which is not an absolutely true circle. Further, the vibration set up in working, and the constant tendency from centrifugal action for the cylinder to roll forward, have a certain bearing on the subject. For these reasons there are some persons who contend that during the grinding of the cylinder teeth the cylinder should be run at its normal velocity, and the emery grinding roller be driven at a surface speed approximating to that of the cylinder. While this contention is theoretically correct, the disturbance caused by the high velocity of the cylinder is not of practical moment, and it is found to give the best results to run the cylinder slowly and the emery roller quickly. In all operations in which a true surface has to be established these conditions are found to be the best, and the grinding of a carding engine cylinder forms no exception to the rule. The danger of damage to the wire joints is much less likely, and the high speed of the grinder aids materially in light grinding, which it will be shown is of great moment. It is, therefore, the universal practice to reduce the normal speed of the cylinder to one varying from 7 to 1-1/2 revolutions per minute, and several special devices are in the market for the purpose. Before passing on to describe these, it may be said that the cylinder is ground by an emery roller, sustained in special brackets fitted to the machine framing, the position of which is shown in Fig. 44 at =R=. A similar method of procedure is adopted with the doffer, the brackets being placed at =S=.

(171) The most common appliance to obtain a slow motion of the cylinder is that known as Sykes’, which is shown in Fig. 89, as made by Messrs. Dronsfield Brothers, of Oldham. This consists of fast and loose pulleys, which are driven by a strap from a pulley on the line shaft. The pulleys are sustained in a frame which also carries a short strap, on which is fastened at one end a bevel and at the other end a worm. The frame is supported by the two legs shown, which can be adjusted to any length. The worm wheel is fixed on the cylinder shaft in place of the ordinary pulley, and is driven by the worm and gearing as described. A slow motion is thus given to the cylinder, and at the same time the grinding rollers are driven by bands or cords from grooves formed in a flange on the fast pulley.

(172) A motion patented by Messrs. John Hetherington and Sons is illustrated in Figs. 90 and 91. In Fig. 92 a side view of a carding engine is shown, with the motion applied to it. On the stud =G=, which usually carries the intermediate band pulleys, shown by the dotted line =I=, the boss =F= of the supporting frame =A= is fitted. The apparatus is shown in Fig. 90 in section, and consists of the supporting frame named, the boss =A^{1}= of which forms a bearing for the shaft =B=, with the eccentric =B^{1}= formed on it. On one end of the shaft the double grooved pulley =C= is fixed, by means of which it is revolved. An internal rack =A^{2}= is formed on the fixed frame =A=, and adjoining the latter is the compounded pulley =D=. =D= is also formed with an internal rack and a single grooved pulley, and revolves on the outer end of the shaft =B=, being kept in position by the nut and washer shown. There are thus two racks, each containing the same number of teeth, one fixed and the other free to revolve. Mounted on the eccentric =B^{1}= are two wheels =E= =E^{1}=, the latter being smaller in diameter than the other, this arrangement being shown clearly in front view in Fig. 91

(173) The action of this mechanism is as follows: The pulley =C= is driven by a band =K= passing over the pulley =J= on the main cylinder shaft =H=. In this way =C= is revolved, and the eccentric movement of the shaft =B= causes the wheel =E=^{1} to fall into gear with the rack =A^{2}=. This gives a rotary motion to the wheels =E= =E^{1}=, and the larger diameter of =E= causes it to revolve at a greater rate than =E^{1}=. The revolution of =B=, in addition to setting up this rotary motion in the compound wheel =E= =E^{1}=, also puts E into gear with the rack =D^{1}=, and causes the latter to revolve. The motion of the pulley =C= is thus communicated to =D=, but the latter is revolved at a much slower velocity in the direction of the shaft. By proportioning the pulleys and wheels the necessary reduction in speed can be obtained. The revolution of =D= is communicated to the cylinder by the band =L= passing over the grooved pulley =M=.

(174) In the machine as made by Mr. Samuel Brooks, the motion is compounded with the barrow wheel detaching motion, as illustrated in Figs. 93 and 94. On the same stud as the barrow wheel is a helical wheel =C=, which is driven from the former by a clutch, and which engages with a wheel =D= fastened on the lower end of a shaft placed at an angle of 97°. On the other end of the shaft a worm =F= is fixed, and gearing with the wheel =G=. During grinding the barrow wheel is disengaged by means of the lever in which the stud carrying the former is fixed, and the worm is thrown into gear. The speed of the cylinder is thus reduced to about one revolution, the necessary rotation of the wheel =C= being obtained from the pulley on the cylinder shaft. When it is desired to grind the cylinder the strap is thrown on to the pulley, and the necessary rotation given to the barrow wheel =B= and helical wheel =C=. The arrangement thus described is always in position, and does not require separately attaching to the machine, as is the case with most of the motions in use.

(175) Another form of apparatus recently introduced by Mr. Thomas Knowles is the one shown in Figs. 95 and 96. In this case the boss of the loose pulley =L= carries a pinion =J= inside the pulley which gears with =I=, fixed on a short shaft borne by a central plate. Through the train of wheels =H G F E C= and =B= the central pinion =A=, fastened on the inner boss of the fast pulley =M=, is revolved. Over the central plate, in which the spindles on which the wheels =E F G H= and =I= are fixed, are fitted, a band =K= is passed. By tightening the latter the plate can be prevented from revolving. In grinding, the strap is moved on to the loose pulley, the band =K= is tightened, and the revolution of the pulley gives motion to the whole of the wheels, thus reducing the ultimate velocity to the required extent. During work the band =K= is slipped off the plate, and the whole nest of wheels is carried round with the pulleys as they revolve.

(176) The rollers used for grinding the cylinder and doffer are made in two forms. One of these is shown in Fig. 97. It consists of a light roller made with a thin wrought iron shell secured upon a shaft, running in brackets fixed to the frame side. The driving pulley is fastened at one end, and at the other is a traverse arrangement, consisting of an eccentric rotated by a worm on the shaft. By means of a short rod the revolution of the eccentric gives a small lateral movement—about an inch—to the roller during the whole time it is in motion. The surface of the roller can be covered with emery in the ordinary manner, and is either made plain or grooved. Another method adopted by Messrs. Dronsfield Brothers, is to wrap round the roller a narrow fillet of emery cloth, either plain or grooved as desired. In covering, one end of the fillet is passed into the slit Fig. 98, and is then secured by the clamp shown. About half of the width of the fillet is left projecting, and after it is secured, it is wound on by revolving the roller. As soon as the fillet is wound its loose end is passed into one of the three slits Fig. 99, formed at the other end of the roller, and is secured by the clamps. The ends are then trimmed off, and the roller is ready for its work. The grooved covering is preferred by many carders, as it is found to grind the wire teeth better, and to meet the various requirements of the trade it is made in various degrees of fineness. Three of these are shown in Figs. 100, 101, and 102, the coarser of the three being used for mild steel or iron wire, and the finer variety for hardened and tempered wire. All the rollers are carefully made, so as to be evenly and truly balanced, and great care is taken to ensure them having a perfectly true surface on which to wrap the filleting. This method of covering rollers has a good many advantages, the chief of which is the ease with which the operation can be conducted as compared with the older method of covering.

(177) Another form of roller is shown in Fig. 103, this being a modification of the Horsfall type. It differs from the one previously described, which covers the whole width of the surface to be ground, whereas the Horsfall roller is a narrow roll to which a rapid reciprocal movement is given across the surface of the wire. It consists of a light shaft, in which is formed a straight groove for the greater part of its length. In the bottom of this a zig-zag groove is formed, into which a fork enters. The fork in the roller shown in the illustration is mounted in a plug fitted into the boss of the grinding roller, and can be removed and replaced without difficulty. Oil pads are fitted at each end of the grinding pulley, and are covered with brass caps, so as to keep them in position. In this way the parts are always efficiently lubricated, while at the same time grit and dirt are excluded. The emery roll or pulley is traversed as described by the engagement of the fork and the spiral groove, and as soon as it reaches either end of the longitudinal groove, it is automatically reversed. This action takes place throughout the whole period of grinding. On the whole, the employment of the Horsfall type of roller is not so great as that of the continuous roller shown in Fig. 97. When the latter is used all the teeth are ground in a straight line across the cylinder, while the use of the Horsfall implies the grinding of the teeth in a spiral line over the whole surface. It is quite true that the whole of the teeth are ground in either case, but there is an obvious advantage in treating all those in the same line at one time.

(178) In grinding the cylinder the cover above the doffer is removed, and the wire surface bared. The cylinder is then stripped in a way which will be afterwards described, and the roller is fixed in brackets =R=, Fig. 44, placed to receive it. The construction of these brackets is a matter of importance. They are accurately planed, and fitted so as to move to and from the cylinder centre in radial lines. They must be so fixed to the bend or framing that they are quite level and parallel with the surface of the cylinder or doffer, as otherwise they would grind more off the wire at one side than the other. This is an essential feature, and it is also required that they should be set so as to grind lightly, otherwise there is a danger of producing hooked teeth, which are very detrimental to good work. Generally, the remarks just made apply also to the grinding of the doffer, which is effected by means of the brackets =S=, the doffer cover being removed, and the doffer stripped.

(179) The grinding of the flats in revolving flat engines is usually performed by a roller sustained by the brackets =T=, which are fitted on the side nearest the cylinder, with a surface against which the flat end is pressed by the weighted levers shown. The accurate grinding of the flats involves a nice problem which is worth a special explanation. As was stated in the last chapter, paragraph 117, the flats are formed with a heel which throws up the edge nearest the licker-in, and thus prevents any rolling up of the fibre. In Fig. 104 a diagrammatic representation of the relative position of the flat end and wire surface is given. The flat end is shown by the letters =A B C D=, and the wire by =C D E F=. It will be noticed that the line =E F= is not parallel with =A B=, which represents the surfaces on the top of the flat ends, but is parallel with =C D=, which represents the surface on which the flat travels. It is obvious that if during grinding the flat is held against a prepared surface, by means of its face =A B=, and traversed thereon, there will be a corresponding formation of the face =E F= of the wire, which would become parallel with =A B=. If this happened, the whole object of reducing one of the faces on the surface =C D= would be destroyed, as while the heel would be in that surface it would be removed from the wire face. But if, on the other hand, the flat is sustained on the face =C D= during its passage under the grinding roller, the parallel relation of =C D= and =E F= is not altered, and therefore the flat is as fit for its work as before grinding. How to sustain the flat when being ground so as to maintain this parallel position is the problem, which is, however, in a fair way towards solution. The steady, forward movement of the flats during grinding somewhat increases the difficulty, but as it is one of the necessary elements of the case it must be duly taken into account.

(180) In Fig. 105 an illustration is given of an arrangement patented by Messrs. Knowles and Tatham. The grinding bracket carries a pivot on which the weighted lever =F= oscillates. The unweighted end of =F= presses against the top side of the flats as they are successively brought within the sphere of its influence, being of course turned upside down at this point. A plate =B= is fixed in the position indicated, being of sufficient width to engage with the flat end without touching the wire. =B= is, as shown, formed with a shoulder, the difference in the height of the two planed surfaces, =D= and =E=, thus obtained being equal to the heel of the flat. The grinding roller is indicated by the dotted line, as is also the bearing. The position of the shoulder on =B= is such that the whole of the wire has been ground before the flat end passes over the shoulder, and the flat is thus kept approximately in correct position for maintaining the parallel relation of the wire and working faces. Before the wire on the succeeding flat begins to be ground, one of the ridges on it passes on to the lower surface =E=, so that the wire face is brought into a horizontal position.

(181) In Fig. 106 an arrangement made by Messrs. John Hetherington and Sons is illustrated. The ordinary grinding bracket is replaced by another one, fixed in the same position, which carries at its upper end a slide =K=. This moves in a bed prepared for it in the bracket, and has the necessary bearings formed for the roller =M=. Attached to the slide =K= and the bracket is a spiral spring =T=, which always tends to draw =K= against a stop. The vertical lever =L= extends upward, and its upper end presses against the inner side of the horn of the slide =K=, so that when =L= is oscillated the slide is moved forward. On the same spindle, forming a centre for =L=, a lever =Q= is fixed, which has a vertical tail-piece =P=. A rib is formed on =L= through which a screw is threaded, the point of which presses against the edge of the tail =P=, and is, when adjusted, locked by means of a nut. The flats pass beneath a plane surface fixed to the inside of the grinding bracket, and their working faces are pressed against it by means of the weighted lever =P=. The line of the flat traverse while so pressed is shown by the dotted line =U V=. When a flat enters upon the surface on the bracket it is pressed upwards, as described, and, while so held, the grinding bracket is moved forward over the teeth by the action of the cam =R= fixed on the chain roller shaft. The rotation of =R= depresses the lever =Q=, and gives the required movement to the lever =L= and to the slide =K=. It will be noticed that the slide =K= is placed at such an angle that it traverses to meet the flat, the object of this being to establish such a line of motion of the grinding roller as corresponds to the inclination of the flat relatively to the cylinder during work. The roller traverses in the opposite direction to that in which the flat moves for a certain distance, when it returns and again passes over the wire surface as that is moving forward. During the reverse movement it moves vertically to the same extent as previously made, so that in both cases it grinds the wire points in the desired plane, and thus maintains the true relative distance of both sets of teeth. By the time the reverse movement has taken place, the flat being ground has moved forward sufficiently to pass beyond the range of the roller, and the latter is then ready to grind the next of the series. In this device the principle of grinding by the movement through an angular plane of the roller axis is the central idea, and there can be no question that this is a very likely method of getting a true result. For it is obvious that if the flats were held stationary, and the roller traversed in an inclined plane, the necessary regularity would be given to the wire surface with great exactitude. A similar result is obtainable by similar means although the flats may be slowly moving, and this is demonstrated by the motion just described, which has been used with great success.

(182) In Fig. 107 is shown a side elevation of Edge’s grinding apparatus, which is made by Mr. Samuel Brooks. Its essential feature consists of a curved plate =B=, which is fixed either to the grinding bracket =A=, or to a fixing attached to it. Over this the flats =C= traverse, and when they reach the centre the snugs at the back are drawn upon the raised portion =B^{1}=, which is sufficiently long to permit of each flat being in contact with it the whole of the time it is passing under the grinding roller. A plate =D= is maintained in a position above the flats, and the method of forming it and regulating its position constitutes one of the chief features of this arrangement. The grinding roller =G= is sustained by a bracket or bearing, in which its axis =F= rotates. The bracket rests upon a cylindrical stem =E^{1}=, fitting inside a cup, and also in a similar recess or barrel =E=. The latter has a long boss which forms part of, or is attached to, the plate =D=, and =E^{1}= is screwed and fitted with two cylindrical nuts. Thus, by adjusting the nuts, the distance of the centre of =F= from the under surface of =D= can be varied at will, and the pressure of the grinding roller upon the wires fixed. The action of this mechanism is as follows: As the flats =C= traverse they ride upon the projection =B^{1}=, and their working surfaces are forced against the under side of the plate =D=. The latter is shaped so that the traverse of the flat causes one side of it to become depressed and the other to be elevated. The peculiarity of this arrangement lies in the fact that the change of position of the plane of the flat faces is sufficient to ensure all the wire points being presented to the action of the grinding roller in their correct plane. In other words, the effect is nearly identical with that obtained when flats are held separately in a stationary frame, and the grinding roller passed over them. Not less important is the ease with which the position of the setting plate =D= can be adjusted relatively to that of the grinding roller. This power of adjustment is the chief feature of this mechanism, and as, when it is once made it is constantly maintained, each of the series of flats will be so ground that the distance of its wire points from its working face will be identical with that of each of its fellows. Thus a set of thoroughly good flats is obtained, each of which is in the best condition to do its work. A further point which it will, perhaps, be well to mention is, that the power of adjustment, existing by reason of the two nuts shown, permits of the flat ends being subject to the required pressure during grinding, which is afterwards constantly maintained.

(183) Fig. 108 represents in partial section Higginson and Mc.Connell’s patent, which has been adopted by Messrs. Dobson and Barlow. It consists of a bracket =A= fixed as usual to the machine framing, and having at its upper portion =C= a slot in which the small slide =D= is fitted. This slide has its underside shaped to the extent necessary to give the flats the required amount of inclination during grinding, and at the end of this surface is formed with a lip as shown. A spiral spring =E= is fitted in the slot, and presses against the end of the slide when the latter is in its normal position. The flats =G=, of which there are only two shown, travel in the direction of the arrow, and when turned face up the chain lugs mount upon the nose of the short lever =H=. A bell-cranked lever =F= is fixed on the same shaft as =H=, its vertical limb having a set screw =I= fitted, by which its range of movement is limited, while its horizontal arm carries a balance weight. As the flats traverse they alternately mount upon the higher part of =H=, and are thus pressed into contact with the inclined part of the slide =D=. Immediately afterwards the flat comes in contact with the lip, which prevents its further forward movement. At this time it is in such a position that the wire surface is horizontal, and while in that position it is passed under the grinding roller =B=. As it traverses it carries the slide =D= along with it, gradually compressing the spring =E= until the wire has been entirely ground. When this has happened the slide makes a little further forward movement—its entire traverse being shown by the two vertical dotted lines—when the chain lugs pass off the nose of =H=, and the flat falls clear of the slide =D=. Immediately this occurs the spring =E= pushes the slide back, and it is ready to receive another flat. The chief feature of this motion is the employment of the sliding wedge. When the flat is pressed on to this it is held as though it was on a stationary bed, and is, by reason of the horizontal position of the slot, maintained in a constant plane. Thus the wire surface is presented to the action of the roller in a plane parallel to that of the slot, so that, whatever the variation in the flat end caused by wear, it is not affected. There is another point which is somewhat important. The tension upon the chain links caused by the friction of the flats upon the bend is very considerable, and results in a gradual lengthening of the pitch of the chain. If, in addition to this, the extra friction set up by the pressure of the lever =H= on the flat, thus causing the latter to be forced against the surface of a plate, be taken into account, this tendency to lengthen will be increased. The extent to which this is to be considered varies naturally with the pressure exerted. Although it is not perhaps great it is appreciable, and it is a matter to be considered. In Higginson and Mc.Connell’s motion this friction is slight, as the slide =D= is arranged to move without much power, although the compression of the spring towards the end increases the amount required. As the wedge springs back into position it has to slide over the face of the next of the series of flats, which by this time has passed upon the end of the lever =H=. Thus, although the flat travels forward without friction, there is a certain amount to be considered as the wedge is passing into position on each flat, the pressure being then exerted as in the case of a fixed plate until the flat presses against the lip, and the wedge begins again to slide.

(184) In Fig. 109 a side elevation of an arrangement made by Messrs. Platt Brothers and Company, Limited, is shown. In this case, also, the device of a sliding angular surface is employed. A slide =H=, which is guided in the upper part of the grinding bracket, and upon which a pull is constantly exercised by the balance weight =M= and chain shown, has affixed to its lower side the angular or inclined surface against which the flat end is pressed during grinding. As in the mechanism just described, the surface to receive the flat is formed with a lip, so that the forward traverse of the flats causes it and the slide =H= to move in the direction of the arrow. A slight curve corresponding to that of the bend is given to the sustaining surface of the slide, and the flat is thus held in a corresponding position to its working position. On the axle of the chain wheel by which the flat chain is driven is a toothed cam plate =K=, which is shaped as shown, so that it can give a forward movement to the lever =L=. The latter has fixed in it a tooth or catch, which constantly presses on the surface of the wheel =K=. The lever or bar =L= is formed with a slot at one end, with which a pin fixed in the end of the chain wheel axis engages, so that the lever can freely slide upon it. The other end of the lever is jointed to a lever =B=, fixed upon a short shaft on which is also fastened the short lever =F= and the curved arm =D=. There is a similar arrangement of mechanism at either side of the machine, and the two arms =D= are coupled by means of a round bar =E=, which acts as a weight. In this way a certain torsion is put upon the short shaft, and a tendency is set up in the lever =F= to move upwards. In doing so =F= presses against the slide =G= placed inside the framing and bend. The upper end of =G= when pushed up presses against the back of the flat and forces it against the inclined surface, where it remains until the flat is ground.

(185) The action of the mechanism is as follows: When a flat has passed under the grinding roller completely the rotation of the wheel =K= causes one of the teeth to push the lever =L= forward, and so oscillate the shaft upon which the lever =B= is fastened. This raises the arm =D=, and relieves the slide =G= of the pressure exerted by the weight =E=. The flat =I= at once falls out of contact with the surface of the slide =H= which is thus free to fall back into position to receive the next of the series, this being the position shown in Fig. 109. It is essential to notice that, while the backward movement of the slide =H= is taking place it is out of contact with the flat, so that, neither during its forward or backward traverse is there any extra tension put on the chain. Immediately the slide has completed its movement the engagement of the catch in =L= with the tooth in =K= ceases, and =L= is free to slide inwards, which it is caused to do by means of the weight =E=. At the same time the slide =G= is pushed upwards, and lifts the next flat into contact with the inclined surface on =H=. It only requires to be said further that the pitch of the teeth on =K= ensures the requisite movements being given to =G= to cause the latter to engage every flat in its turn.

(186) The rollers and clearers are ground after removal from their places in the machine. A machine of which Fig. 110 is a perspective view is employed for this purpose, this being the type made by Messrs. Dronsfield Brothers, who have specially devoted themselves to this class of machines. The machine consists of a frame which has bearings formed, in which the shaft of the grinding roller revolves. Affixed to the lower portion of the frame is a counter shaft from pulleys, on which the emery roller is driven at a speed of 300 revolutions per minute. The roller to be ground is borne by the two bearings shown, which are slid laterally by the extremities of arms secured to a transverse spindle sustained by brackets fixed to the framing. The two arms are moved to or from the frame by means of a hand wheel which is keyed on a short spindle, on which is also fixed a worm. This engages with a quadrant fastened on the transverse spindle, so that the rotation of the worm in either direction gives a movement to or from the grinding roller. In this way the card roller is brought into contact with the grinding roller equally over its whole surface, the axis of the bearings in the arms being always parallel with those of the grinding roller. A bonnet is placed above the machine, and the dust is removed by the small centrifugal fan shown. The card roller is driven by a separate strap from the counter shaft.

(187) The flats of self-stripping machines are removed from the latter, and are secured on suitable bearings formed on the frames of a special grinding machine. The bearings are adjustable, so that the correct position is given to the flat during grinding. The faces of the flats when so held are moved across the grinding roller, which revolves at a high speed. As the arrangement is a very simple one, and does not present any great novelty, it is not necessary to describe it in great detail.

(188) As the wire clothing on the cylinder, doffer, rollers, and flats becomes filled with motes, neps, and short fibres, it is necessary to remove these periodically. This operation is called “stripping,” and it is a very important one. Whatever may be said to the contrary, stripping cannot be dispensed with unless some specific be found for the removal of the impurities as fast as they are taken out of the cotton. The plan formerly adopted for this purpose has fallen into disuse, as it implied the stripping of the card during work, and led to the mixing of the stripping with the finished sliver. It has been shown that a clean wire surface is the best for carding, and it will be easily seen that the filling of the spaces between the teeth will materially reduce the elasticity of the wires. Regular stripping is for this reason advisable; but the ease with which, if so carried out, the dirt can be removed, constitutes a further reason for this procedure. Carding speedily becomes poor in quality unless this is looked to, and all spinners should carefully watch this point. Another matter is, that inasmuch as it is practically impossible to strip all the cards simultaneously, the operation should be effected so that there should be an equal proportion of clean and dirty or half dirty machines. These are all little points, but they are of great importance in the effective working of a machine.

(189) The stripping of cylinders and doffers was usually carried out by a wire hand brush, the teeth of which are thrust into the wire spaces and then drawn downwards, so removing the “strips.” This is now entirely superseded by the revolving wire brush, such as is shown in Fig. 111, as made by Messrs. John Whiteley and Sons. This is a roller on which is wound card clothing made of hardened and tempered wire. It can be revolved by hand or power, and is carried in the grinding brackets. In stripping it should be set so that the teeth finally penetrate about 1/16th inch into those on the cylinder, but should be gradually set in to that depth so as to avoid damaging the wire. A speed of 200 revolutions for hardened and tempered, and 150 for mild steel cards is recommended by the makers, the cylinder revolving slowly in the meanwhile. The fleece of strippings thus produced is removed from the roller by dividing it along the narrow uncovered space shown, after which it will lift off by slowly revolving the roller. A similar plan is followed with the doffer. The rollers and clearers are usually stripped by hand, and it is hardly possible to adopt a better plan.

(190) In closing the consideration of the carding engine and its accessories, it is necessary to enforce upon the reader the dictum that good carding is absolutely essential to good work. With it a good even yarn can be made. Without it no such result need be looked for. It is impossible to lay too much stress upon this point, and the care bestowed upon the machine and its clothing will amply repay the spinner. Cleanliness is essential, and it is certain that the want of it often leads to trouble and loss in the subsequent stages of spinning.