Flat Machine Knitting and Fabrics

The purl stitch or links and links machine is a type which may be termed unique in the class of machinery built to make knitted fabrics. It is entirely a European development; in fact, to my knowledge there had been none of these machines built in this country until some time after the war started, when it was impossible to import them.

The chief individual characteristic of purl stitch machines lies in the fact that they have two needle plates, but only one set of needles, and the cams do not act directly on the needles, but act indirectly through what are called jacks. First we will try to get a thorough knowledge of the fabric this machine was primarily designed to make, and the stitch formation required to produce this fabric; then the mechanism and movements of the different parts of the machine will be more readily understood as we proceed with the explanation.

Character of Fabric

Fig. 57 shows a photographic reproduction of the fabric with the top turned over to show both sides, which it will be noted are exactly the same. Fig. 58 is a line drawing showing the formation of the stitch; the course that the yarn takes may easily be followed. This is called the purl stitch and is very popular with milady when making hand knit sweaters, children’s suits, etc.

If the reader will refer back to Fig. 12, he may be surprised to note how near this fabric is like the back of the jersey fabric, while the face of the jersey fabric is so different. I do not think that I should go very far wrong if I put this in the same class as the jersey fabric, the same as the half and full cardigan are classed as rib fabrics. It is made the same as the jersey on one set of needles, but with this difference: In making the jersey fabric the loop is always drawn through the previous loop in the same direction. That is, we will suppose we were making this jersey fabric on an ordinary flat machine, on the front plate only. In this case the loops would always be drawn toward you through the previous loops. Now if we should reverse every course the direction in which we draw these loops, or in other words, if we should draw them towards you when moving the carriage from right to left, and away from you when moving the carriage from left to right, and continued this reversal, we would make a purl stitch fabric.

But, you say, how are we going to do this? The solution is the purl stitch or links and links machine, with its double ended needle, or a needle with a hook and latch on both ends to permit the whole needle to be pushed through the loop every course, thereby casting the previous loops off one end on one course, and off the opposite end on the next course. This system of knitting is such that there can be no obstruction to the free movement of the stitch over any part of the needle, therefore this fact precludes the use of a butt projecting up from any part for the cams to operate on, even if there were no other reason, which there is as the reader will understand after a study of the subject.

This machine is constructed somewhat along the lines of the ordinary flat machine, which we have been studying. Its points of similarity are that the table or stand is the same, it has two straight, flat needle plates, it has a carriage which is moved backward and forward over the needle plates to operate the needles, and the cams or locks are practically the same as in the ordinary single lock flat machine. The main points of difference are that on the purl stitch machine the needle plates are set so that they are flat, or both are on a horizontal plane, and the needle slots of both plates are directly in alignment with one another so a needle may move freely from the front to the back plate, or vice versa. The ordinary flat machine has the needle plates set at an angle of about 90 degrees to one another, and 45 degrees to the horizontal, and they are set lengthwise so the needle slots of one plate are opposite the space between the needle slots of the opposite plate, or in a position so the needles of one plate will come up between the needles of the opposite plate.

Another point of difference is that the purl stitch machine has one set of needles for both plates, with a hook and latch on both ends of each needle and no butts to operate them, while the ordinary machine has a set of needles for each plate with a hook and latch on one end only with a butt on the other end to operate it. It naturally follows that inasmuch as the needle plates are set flat, instead of at an angle to one another, and the needles are operated indirectly through what are called jacks instead of directly on butts on the needles, the construction of the purl stitch machine must be somewhat different from the ordinary flat machine.

Construction of Purl Stitch Machine

Fig. 59 shows a general view of a purl stitch machine built by Dubied & Co. The letter a indicates the carriage, b the handle used to operate the carriage, and c is an auxiliary handle which some knitters like and use, while others take it off, preferring the use of handle b only. The letter i indicates the connection rod for the auxiliary handle; d is the racking handle for racking the back plate, which plate is made to rack over usually about 12 needles. The letter e is a sector of a circle attached to the frame of the machine and acts as a guide and a stop for the racking handle. This may be studied to better advantage in Fig. 60, at e. It has V-shaped notches cut at the proper intervals to correspond to the needle spacing with a V-shaped plunger attached to the handle so that when this plunger springs into one of the notches it brings the needle slots of the back plate into alignment with the needle slots of the front plate.

The secondary handle d-1 is for releasing this plunger to permit the handle to be moved. It will be noted that there are holes in this sector, one back of each notch in the edge, and in two of these holes there are pins. These pins may be placed in any desired hole and act as stops for the racking handle and in this way save the operator the trouble of stopping to count the number of notches every time he racks, as on this class of work racking over anywhere from two to twelve needles at one time is common practice.

To go back to Fig. 59, letter f is a counter for counting the rounds, g indicates two yarn carrier stops, one on each side of the bar or gib, while h and h are the yarn take-up frames and springs. Letter j indicates the two gibs or ways on which the carriage slides, and k is the bar for carrying the yarn carriers.

Now to get an insight into the principle of the method of making this purl stitch we will first give our attention to Fig. 63, which is a line drawing of a needle and the two jacks which are required for each needle in their proper relative positions.

As will be surmised after looking at the drawing, the jacks are moved forward and backward by cams operating on the butts a and a, which project above the surface of the needle plate in the same manner as the cams operate on the needle butts in the ordinary flat machine. The jacks operate the needles by catching the hook of the needles in the clutches b and b of the jacks. These needles are simply passed, so to speak, back and forth across the throat, between the needle plates, from one jack to the opposite one on each course, and in that way they reverse the direction of the draw of the loop on each course.

We will now give our attention to Fig. 62, which shows the under or cam side of the carriage. It is understood, of course, that lengthwise of the carriage, or the direction of movement, would be what is crosswise or right and left in the illustration. It will be noted that the locks or stitch cam arrangement are, on the whole, practically the same as in the ordinary flat machine. This would apply to the cams and locks including a, h, k and g, also b, i, l and j. The bridges c and d are for another purpose.

It will be noted that while the stitch cams h and i, also g and j, are exactly opposite one another, the cams a and b are not. The bridges c and d have perfectly flat smooth surfaces except at points e and f, and here they have a concave portion about one-eighth of an inch deep. The space between bridge c and cam k, also between bridge d and cam 1, is filled by the needle gib 1, Fig. 60, and its mate on the back, which cannot be seen, when the carriage is on the machine. The reader should carefully study the points just gone over, that is, the location of the cams a and b in relation to each other, and the bridges c and d with their concave spots e and f, in order to fully grasp their relation to the jacks and needles in the operation of the machine.

We will now give our attention to Fig. 60, where it will be noted that the front gib 1 is abnormally wide. The back gib is the same, and inasmuch as it cannot be seen we will assume that it is also marked 1 and hereafter call it back gib 1. Just below the center, laterally, of the front needle plate we see a row of jack butts which are in working position. In the back plate we see jack butts in every slot but they alternate with three up in working position, and three down out of working position. It should be understood clearly that any jacks that are moved to the outer edge of either plate will not operate as they are out of range of the cam system, the same as in the ordinary flat machine.

Let us now bring together the needles and jacks in Fig. 63, and the needle plates in Fig. 60. The butts of the jacks a (Fig. 63) are what we see projecting above the needle plates in Fig. 60. The hump c (Fig. 63) lies under the gib 1 (Fig. 60). The reason for having this gib extra wide is to cover this hump during most of the knitting operation in order to keep the needle captive. The depth of the needle slot is just sufficient to allow this part of the jack to slide under the gib freely without any up and down play, therefore it follows that when the hook of a needle is caught in the clutch b, as in jack number 1 in Fig. 63, that needle must move backward and forward with the jack. When the jacks are moved forward to the point where the butts would be near or against the gib 1 (Fig. 60) the hump c (Fig. 63) would be inside and clear of the gib 1, toward the center of the machine, therefore the shank of the jack being narrower than at the hump, a slight draw on the needle would free it from the jack as the clutch d, which holds the needle, is beveled off for this purpose. This being the case it follows that when the jacks are in this position the hooks of the needles may be easily pushed under and into the clutch b of the jacks. This is how the machine is filled with needles to begin with, or imperfect ones replaced with new.

It will now be necessary to study Fig. 62 in connection with Figs. 60 and 63. Referring to Fig. 62, the space between the cam k and bridge c, also cam 1 and bridge d, as noted before, is occupied by the two gibs 1 (Fig. 60) when the carriage is on the machine. The bridges c and d (Fig. 62) come down to the needle plates and the surface we see is on the same plane as the under side of the gibs 1, Fig. 60. We have just had the statement that when the butts of the jacks a (Fig. 63) were moved up to the outside and close to the gibs 1 (Fig. 60), the hump c of the jacks would be just inside and clear of the gibs 1, therefore could be raised sufficiently to slip the hook of a needle in or out of the clutch b of the jack. This is true only at a time when the carriage is not over and operating the jacks.

When these are moved up to this point by the cams the hump c of the jacks would come under the bridges c and d (Fig. 62), therefore could not raise up to release the needles except at the narrow concaves marked e and f in the bridges. These concaves, it should be noted again, are not opposite one another. The distance between the top or narrow part of cam a and cam b is such that when the butts of the jacks have moved up to this point the clutch b of both of the opposed jacks cover a hook of the needle. In looking at Fig. 62, the top half of the carriage would be the part covering the front needle plate and operating upon the front jacks, and the bottom half would do likewise on the back plate. When the carriage is at the left end of the machine, when making the purl stitch the needles should be in the front plate, and when the carriage is at the right end of the machine the needles would be in the back plate. This relative position is always the same when making the purl stitch.

I have assumed that the reader understands that a jack and a needle together would, when in a normal position as shown by the butts in the front needle plate in Fig. 60, reach just to the throat between the needle plates. Having the different parts and their relative positions in our mind we will now proceed with the modus operandi. We will assume that the carriage is at the left end of the machine, therefore the needles would be in the front needle plate and under the control of the front jacks, as the hooks would be in the clutch b (Fig. 63) of these jacks, while the hump c being under the gib of the needle plate will not allow the needles to escape. To obviate some of the difficulties the reader may have in understanding this explanation we will assume that the carriage as shown in Fig. 62 is stationary, and the plates with their jacks and needles are the parts that are moved.

The outline of the camway may be easily traced as it is practically the same as the ordinary flat machine with which the reader should be familiar and the action on the needles, through the jacks, is the same until they reach the first inside corner of the cam b. If the reader will take a straight edge and lay it on the illustration, he will find that this corner of cam b is just in line with the concave e in the bridge c, and also with the center of the flat portion of the cam a. This being the case, it follows that the center of the flat portion of the cam b must be in line with the left inside corner of cam a and the concave f in the bridge d.

It should be understood that as the needles are moving across the throat between the needle plates, the stitch or loop opens the latches, and guards are provided to keep them open until the needles are ready to draw the new loop through the previous one.

Now to return to where we left the needles and jacks at the right inside corner of cam b. The jacks of the back plate have reached their innermost position, and the heads or humps c (Fig. 63) lie under the bridge c (Fig. 62). At the point where the front jacks opposite are reaching their innermost position, the heads or humps c of the back jacks come under the concave e, which allows the hook of the needles, just coming forward from the opposite plate, to raise up the head and enter the clutch b of the jack. As they move farther to the left, the heads of these back jacks are under the plane surface of the bridge c, which secures the needles to these jacks. As the jacks start to move back toward their outermost position, the heads of the jacks of the front plate are under the concave f of bridge d. This allows the needle hooks of this end to draw out and release themselves from the jacks of this side, and be drawn through the loop to the back plate, and by this means to cast the previous loop off from the back plate toward the front one.

Upon the return from left to right, the needles are exchanged from the back plate to the front one in the same manner, only of course, the action is just opposite to that just explained. Therefore, the needles would pass through the loop from the back to the front plate, and cast off the previous loop from the front plate toward the back one. This would make the purl stitch.

While the machine was designed primarily to make this purl stitch, there can be made on it a larger variety of stitches than on any other machine, but in general practice the stitches made are limited as a rule to the purl, jersey and plain rib, 1 and 1, 2 and 2, etc. The term 1 and 1 rib means one needle in each plate alternately. The term 2 and 2 rib means two needles together alternating in each plate without a needle working between the two from the opposite plate. It is also possible to make the half or full cardigan stitch.

The jersey stitch may be made by one of two methods. First, when the needles are all in one plate move the jacks in the other plate to their outermost position, where the cams of that side cannot operate on them and the needles will stay on one side as there are no jacks operating on the other side to take them across. Second, by moving the handle b, Fig. 61, to the left. By doing this we would draw the cams a and b (Fig. 62) up into the cam plate out of working position, therefore the jacks would not move to their innermost position so the needles would not move far enough forward to meet the opposite jacks and could not be taken over into the opposite plate. This system of being able to operate any number of selected needles, or all of them, on either the purl or jersey stitch, either alone or in combination with the rack, is the base or principle used to make practically all the designed or pattern work produced on the ordinary purl stitch machine.

Fig. 61 shows the top side of the carriage. The letter a indicates the handle for operating the carriage; b is the lever for changing the stitch from purl to jersey, or vice versa, by raising out or putting into operation the cams a and b, Fig. 62. The letter c shows the lever for changing yarn carriers while d1 and d2 are the slides for changing the length of stitch. This change is made the same as has been explained for the ordinary flat machine; that is, by shifting the stops, of which there are three for each stitch cam or six on each of the slides d1 and d2.