Looms Should Be Adapted to Make a Wide Variety of Goods—Take-Up and Let-Off Motions—Making the Rubber Warps for Different Classes of Web—Importance of Uniform Tension—Defects from Uneven Tension and Chafing of Threads
The greatest care is necessary in planning out the details of the harness. On account of the great length it becomes necessary that everything possible be done to avoid any chance of warping or sagging, for the least irregularity which may be developed will of course interfere with the evenness of the shed. The harness frames must be made of the very best stock obtainable, thoroughly seasoned, and absolutely straight grained. Each frame must be supported at regular and frequent intervals by stays or supports mortised in the runners. These stays are slotted at top and bottom to receive the heddle bars and keep them accurately in line, and thus prevent them from catching on the neighboring harness during the operation of the shedding process.
It is necessary also that the top and bottom heddle bars be accurately spaced so as to allow proper freedom for the heddles to ride easily on the bars, and thus avoid any binding of heddles which would have a tendency to crowd the warp stock together and prevent clearance of the shed. Steel heddles are preferable to ones that bend and twist more or less and get out of alignment. They are made from tempered steel which is very flexible and they have round cornerless eyes that cannot possibly catch or chafe the warp threads. They adjust themselves automatically to the frame and cannot twist or bend while at work, and are made to accommodate themselves to every conceivable kind of goods.
Install Looms for Wide Range
In installing looms for narrow elastic fabrics it is advisable to make ample provision for creeling the warps necessary for the different fabrics which may from time to time be required. In the manufacture of the light single cloth garter webs, not more than two warps to the piece are required, a face warp and a gut warp, and the temptation to save a little in the initial cost possibly may suggest a limitation of creel spaces to immediate requirements. Added expense may seem for the time being an unnecessary burden. But very soon there may arise a call for other goods which cannot be made within the limitations of the two bank creel; therefore changes become necessary which are generally much heavier than first cost would have been.
Nothing less than a five bank creel should be installed. Many times the availability of six banks has solved knotty problems of warp division to care for the various weaves and materials employed in some constructions. If the entire capacity of the larger creel is not required when first starting it will not be necessary to clothe all of it with levers, buttons, etc., which may be procured later. But by all means ample provision should be made for the full frame work and supporting rods for same.
Take-Up Motion
Another important consideration is to make proper provision for a reliable take-up motion, so that the goods may be taken away from the reed while weaving without any liability to variableness. This liability was present in many of the earlier looms and exists in some of the mills today. The old-time fine ratchet gear, even when provided with a number of pawls, is always liable to erratic picking, which alone will ruin an otherwise perfect piece of goods and materially change the cost of manufacturing. A slight irregularity of picking may not be discernible in non-elastic goods, which will be satisfactory so long as the variableness is not easily seen and a reasonable average of picks per inch is maintained. But in elastic goods, where the contraction takes place after they leave the press rolls, every irregularity is revealed and intensified so there is no room to take chances. The only safe way is to employ picking gears making one tooth to each pick of the loom, and then to change the gears when different picking becomes necessary.
In many of the existing looms there has been no adequate provision made for the weaver to let the web back to the reed mechanically when a joining becomes necessary through the breaking of the filling while weaving, or where a quill may have run off unnoticed. It is almost impossible to make a joining satisfactorily without proper mechanism being provided for this purpose. In some of the slow running looms provision is made for this by the operation of each set of rolls independently (see Fig. 1), by means of the ratchet gear and pawl A and worm motion B. This plan has the one disadvantage of taking up too much space between the individual pieces. Where the fabric woven is say four or five inches wide, and the space will admit, it is all that can be desired, and the individually weighted rollers C associated with the motion are admirably adapted to variable pressure.
For the very narrow elastic fabrics, which require considerable roller pressure to hold the web snug and firm while weaving, and where it is necessary to make very accurate joinings after a break has occurred, a better movement is one in which the web roll is placed on the main take-up shaft in the form of a sleeve. It is carried around by the shaft as it turns while the goods are being woven, but can be released and turned both backwards and forwards by a conveniently placed hand wheel, which operates a series of differential gears. This movement is entirely independent of the movement of the main take-up shaft drive.