How To Use An Overlock Machine

[Willy Aucoin]

Aserger, sometimes called an overlock machine, is a must for any sewist wanting to produce a professional-looking project. Rather than just stitching fabrics together and leaving loose edges, a serger trims off the seam allowance, encases the fabric edges and creates the seam all in one step. This has several benefits. First and foremost, it prevents the fabric from unraveling. It also increases the durability of the finished project. Serged seams are a particularly useful technique for stretchy fabrics. Added durability is achieved by using multiple threads per overlock stitch.

An overlock is a kind of stitch that sews over the edge of one or two pieces of cloth for edging, hemming, or seaming. Usually an overlock sewing machine will cut the edges of the cloth as they are fed through (such machines being called sergers in North America), though some are made without cutters. The inclusion of automated cutters allows overlock machines to create finished seams easily and quickly. An overlock sewing machine differs from a lockstitch sewing machine in that it uses loopers fed by multiple thread cones rather than a bobbin. Loopers serve to create thread loops that pass from the needle thread to the edges of the fabric so that the edges of the fabric are contained within the seam.

Overlock sewing machines usually run at high speeds, from 1000 to 9000 rpm, and most are used in industry for edging, hemming and seaming a variety of fabrics and products. Overlock stitches are extremely versatile, as they can be used for decoration, reinforcement, or construction.

J. Makens Merrow and his son Joseph Merrow, who owned a knitting mill established in Connecticut in 1838, developed a number of technological advancements to be used in the mill's operations. Merrow's first patent was a machine for crochet stitching, and the Merrow Machine Company still produces crochet machines based on this original model. This technology was a starting point for the development of the overlock machine, patented by Joseph Merrow in 1889. Unlike standard lockstitching, which uses a bobbin, overlock sewing machines utilize loopers to create thread loops for the needle to pass through, in a manner similar to crocheting. Merrow's original three-thread overedge sewing machine is the forerunner of contemporary overlocking machines. Over time, the Merrow Machine Company pioneered the design of new machines to create a variety of overlock stitches, such as two- and four-thread machines, the one-thread butted seam, and the cutterless emblem edger.

A landmark lawsuit between Willcox & Gibbs and the Merrow Machine Company in 1905 established the ownership and rights to the early mechanical development of overlocking to the Merrow Machine Company.

Throughout the early 20th Century, the areas of Connecticut, US and New York, US were the centres of textile manufacturing and machine production. Consequently, many overlock machine companies established themselves in the Northeastern United States.

In 1964 several engineers and managers at one Japanese manufacturer[which?] redesigned the industrial serger they were currently manufacturing as a smaller, lighter model intended for home use. They presented their concept to their employer, and after it was rejected they quit and formed the Juki Corporation.

Nick Tacony, founder of Tacony Corporation, introduced machinery for producing the overlock stitch (so called "baby lock") to the United States market. This allowed sewing enthusiasts to produce clothing with finishing seams like those made by industrial garment manufacturers.[1]

Overlock stitches are classified in a number of ways. The most basic classification is by the number of threads used in the stitch. Industrial overlock machines are generally made in 1, 2, 3, 4, or 5 thread formations. Each of these formations has unique uses and benefits:

Additional variables in the types of overlock stitches are the stitch eccentric, and the stitch width. The stitch eccentric indicates how many stitches per inch there are, which is adjustable and can vary widely within one machine. Different stitch eccentrics create more or less dense and solid-looking edges. The stitch width indicates how wide the stitch is from the edge of the fabric. Lightweight fabrics often require a wider stitch to prevent pulling.

Adding extra variation in stitch types is the differential feed feature, which allows feed to be adjusted; extra-fast feed creates a ruffled or "lettuce-leaf" effect. Finally, some merrowing machines contain parts to roll the fabric edge into the stitch for added durability.

An overlock sewing machine, or serger as it is commonly known, can trim, stitch, and overcast seams as they sew. They can also be used for applications such as inserting a zipper and creating beautiful decorations with certain stitches. They sew faster than conventional sewing machines at up to 1,700 stitches per minute. Because of these features, an overlock machine can save time and give a professional appearance to constructed items.

The overlock can also be used to finish the edges of seams. Decorative effects can be achieved by using special threads in the loopers. Threads, such as metallics, silks, and perle cotton, can be used to sew seams or to finish garment edges. For special effects, fine knitting yarn, buttonhole twist, crochet thread, and even narrow ribbon can be used.

Overlock sewing machines are specialized, but they do not replace the conventional sewing machine. Overlocks form interlocking stitches using one or two needles and one or two loopers. The overlock stitch is more like crochet or knitting than the stitch of a conventional machine. Loopers replace the traditional bobbin and interlock threads together.

Seam edges are trimmed by blades located just in front of the needle(s). In some models, the upper knife can be rotated up to disengage the cutting action. In other models, one blade must be removed when trimming is not desired.

The type of overlock machine used will determine the kind of sewing techniques that can be done. The price of the machine depends on the number of threads and loopers, so users should consider the configuration that best fits their needs.

A two-thread model is best for finishing seam edges and decorative edgings, or finishing edges for light fabrics (Figure 1). It can also be used to stitch flatlock seams. A flatlock seam is usually sewn with the wrong sides of the fabric together. The seam is then pulled so the seam allowances slip and lie flat inside the stitching. This seam is useful when seaming sweatshirts, jogging suits, and other active wear made from sportswear fleece and velour. It can be used to stitch elastic and lace to lingerie. Hems can also be sewn using some two-thread overlock machines.

A three-thread overlock trims, stitches, and overcasts seams in one operation (Figure 2). The three-thread overlock seam is most useful when sewing knits. It can be used to sew woven fabrics, but not in areas that will receive a lot of stress. The three-thread can also be used to sew pintucks, make narrow rolled hems, and to finish fabric edges. Decorative stitches are possible using a variety of threads or yarns, such as crochet yarn, perle cotton, buttonhole twist, lightweight knitting yarn, narrow ribbon, or metallic thread. Some three-thread models can be converted to do two-thread stitching.

The four-thread overlock will stitch a chain stitch or a safety stitch as it stitches and overcasts seams (Figure 3). The chain stitch model is most useful when seaming woven fabrics. The safety stitch model can be used to sew woven or knitted fabrics. It uses two loopers and two needles. Some four-thread overlock machines convert to do three-thread stitching.

The loopers are the most difficult parts to thread (Figure 4). A special threading tool and a pair of tweezers are usually provided. The lower looper is usually threaded before the upper looper.

The presser foot of an overlock machine is much larger than that of a conventional machine. The pressure on most models can be adjusted to the weight of fabric being sewn. Because the foot is so long, there is seldom a problem of fabrics feeding unevenly as they are sewn. Check the position of the presser foot lifter on the machine. On some models, it is on the right side of the machine near the handwheel.

The throat plate or presser foot will have a special stitch former not found on a conventional machine (Figure 5). On some machines, this former can be adjusted to change the stitch width. On others, the throat plate or presser foot must be changed when a different stitch width is desired. Stitch widths range from less than 1 mm to greater than 5 mm.

The stitch length adjustment procedure varies from machine to machine. Some offer a stitch adjustment dial on the front of the machine. Others require adjustments to be made inside the machine. Determine how easily this adjustment can be made for regular seams or rolled edges.

Although the cutting knives are made to last for many hours of sewing, it is important to determine how easy they are to change (Figure 6). One blade will need to be replaced more often than the other; it is the least expensive of the two blades.

Needles for overlock machines may be special or conventional in design. Determine what type is required and be certain they are readily available. Be sure to select the correct size for the fabric type being sewn, whether using a special or conventional needle.

Some machines have a variety of presser feet to help the sewer with special needs. Feet are available for sewing a rolled hem and for applying elastic, cording, and stay tape to seams. Blind hemmer feet may be available. The rolled hem may also require a special throat plate. Take note of which come with the machine and which must be purchased as extras.

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