Overlock Sewing Machine

[Anush Faigley]

Anoverlock 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.

Other features to look for include an accessory or tool kit, a dust cover, a carrying handle, a built-in accessory storage compartment, and a scrap catcher. Some machines have a base that can be adjusted to create a free arm for sewing.

As you investigate the machines, try several brands and models. Thread each several times. Use the tweezers and needle threader provided, if necessary. Change threads by tying an overhand knot to determine if tension dials must be adjusted to allow the knotted threads to flow through easily.

Notice how easy the machine is to start and stop stitching; some handwheels turn counterclockwise, others rotate clockwise. Is it easy to raise and lower the presser foot? Does the light illuminate the sewing area sufficiently? Is the instruction manual well-illustrated and easy to read?

Sew at slow, medium and fast speeds to learn how easy the machine is to control and to determine if it walks. Some machines have suction cups on the bottom to hold them in place. Check to see how easy it is to sew without trimming the seam edge while the blades are in place. Then, disengage the blades to determine how it is done.

Use a variety of fabric weights and types when trying an overlock. Sew through single thicknesses and two or more layers of fabric. Adjust the presser foot pressure to make matching plaids or stripes a simple process. Check the amount of stretch in the seams you sew.

Finally, before you buy a machine, check the warranty and dealer services available. What does the warranty cover and for how long? Who makes good on the warranty, the manufacturer or the dealer? Does the dealer offer new owner lessons? Will special classes be available to you after you have learned to use it? Does the dealer have a complete and consistent supply of the parts and accessories you will need?

After making your selection, you will want to keep the machine in good operating condition. Keep it free of lint and stray fabric scraps. Use the brush provided to brush away lint from the inside of the machine. Blow briskly on areas that tend to collect a lot of lint; canned air is available for this purpose, or use your vacuum or hair dryer.

Insook Ahn is an Assistant Professor in the Department of Family and Consumer Sciences at NMSU. Her area of expertise is in creative fashion design, sustainable design, functional design, and CAD. She has taught for twenty years at three different universities, and has published research showcasing creative design works.

Contents of publications may be freely reproduced, with an appropriate citation, for educational purposes. All other rights reserved. For permission to use publications for other purposes, contact pu...@nmsu.edu or the authors listed on the publication.

When you first get into sewing, you might wonder how to finish the raw edges in your pieces. You don't want them to just unravel and shed everywhere. Ideally, you'd have a serger for that, but sergers are expensive, specialized sewing machines, and you might not be able to get one right away. Instead, you could use an overlock foot with your sewing machine to give your pieces a faux-serged finish. I tested out different stitches on my machine to see which ones created a finished edge closest to serging.

First, I checked out the overlock and overedge stitches offered by my sewing machine. Read your manual to see what stitches your machine has. Numbers 10, 11, and 14 looked promising because they were described as overedge and overlock stitches, specifically for finishing the edges of fabric. I also tried out 17 and 19 because they looked somewhat close to a serged stitch.

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I confessed to my class that even though I owned a serger, I had only used it a couple of times. Why? I get stressed and confused about threading it! That problem is somewhat common among serger owners, according to my random survey among my sewing friends.

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