Sewing machines threading

Improper sewing machine thread guides cotton core-spun sewing threads)... 

It was James who drove her home with the old sewing machine found on their street. He carried it up to her flat with a box of thread and bobbins then sat there patiently testing it while she made him coffee. James like all the others with so much facial hair you didn t really know what his mouth was saying when he spoke desultorily of going to Chronic on New Year s Eve. 

To make the pocket, simply cut a 4 by 4 inch square of heavy cloth. Sew it with the same color thread as your pants. It s such a small job you don t even need a sewing machine. 

The sewing machine needle is the most important component of the lockstitch sewing machine due to the fact that it is the carrier and deliverer of the sewing thread to the sewing mechanism. If it is not changed regularly, it can be responsible for major quality problems. It is also subject to the most abuse of all the machine parts as it penetrates... 

Chiu-Webster S. Lister, J. R. The fall of a viscous thread onto a moving surface a fluid-mechanical sewing machine . J. Fluid Mech. 569, 89-111 (2006). 

Machine twist n. A hard-twist sewing thread, usually of three-ply construction spun with S-twists and plied with Z-twist, especially made for use in sewing machines. 

The loss in strength due to abrasion in the sewing machine is 25% for the upper and 15% for the lower threads in single- and double-thread chain-stitch machines. During sewing, the thread is subjected to mechanical and thermal stresses, resulting in severe thread deformations. These deformations cause stmctural and mechanical damage to the thread and the fibers. 

The introduction of the sewing thread in the structure of the fabric triggers deformations, which may be dissipated into the bulk of the fabric or result in the development of pucker. The factors that would come into play are the physical and mechanical properties of the fabric, tensile properties of the sewing thread, and some sewing machine parameters. 

The sewing thread develops tension during stitching on the sewing machine, after which it tends to relax by shortening the thread path in a stitch. This can be achieved in two ways ... 

Flat or sew-throngh buttons have holes through which thread is sewn to attach the button. Flat buttons may be attached by sewing machine rather than by hand, and may be used with heavy fabrics by working a thread shank to extend the height of the button above the fabric. 

A sewing stitch may be formed without any material, inside a material, through a material and on a material. All stitch types are formed by a needle penetrating into a fabric while transporting a sewing thread. It is essential to understand how the unique characteristics of every stitch type are dependent upon the mechanical actions of the sewing machine and fabric type, which determines the stitch properties. 

The problems that will be studied include seam pucker and seam undulation faults caused by needle penetration poor material feeding ply-shift, folds and stitch distortion inadequate stitch tension and tension balance and irregular stitch length, skipped stitches and thread breakage. Many researchers have studied methods for automatic detection of some of these problems, which will be reviewed. Future trends will also be predicted, towards the design and development of sewing machines with further sensing and control techniques to overcome the problems herein analysed. 

This problem can be reduced by using lubricants or air cooling of the needle and sewing threads. Some sewing machine manufacturers provide devices for this purpose. A more straightforward solution is to reduce sewing spjeed and/or thread tension. 

Sewing threads with inadequate twist amount and/or direction, affecting the formation of loops necessary for the interlacement of the sewing threads (in general sewing machines use threads with a Z twist). 

Many of the problems described in the previous sections result from adverse process conditions that cause systematic or random defects. Poor properties of the materials being processed — fabrics and threads wearing-out of the sewing machine s components or needles incorrect settings or bad choice of components such as feed-dogs, presser-feet or needles aU of these can be the source for the problems described. The machine operators and quality control team have to be alert to detect these situations as early as possible, because often these defects go unnoticed for whole batches. 

Thread breakage Incorrect threading of the sewing machine Proper selection of quality threads (with good... 

Figure 12.10 Needle thread-force waveforms on an industrial over-edge sewing machine over five stitch cycles, with occurrence of a skipped stitch in the fourth cycle. 

Another interesting source of good advice on sewing problems is the technical documentation offered by sewing machine, needle and thread manufacturers. A selection of some interesting websites follows ... 

Threading a sewing machine is like riding a bike easy once you ve done it successfully once or twice. Sewing machines vary, of course, but the basic principle is the same. 

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