How Does a Serger Machine Work?

3 Steps in 1

A serger machine, most often referred to simply as a serger, works by completing three separate sewing steps at once. The machine sews a seam, trims the excess seam material with a cutting blade and encases the raw edge in an overlock stitch to prevent raveling--all as the material is being passed through the machine. Most manufactured clothing has serged seams.

Threading

A basic serger uses four cones of thread to complete the process of sewing and finishing seams. Unlike a traditional sewing machine, which usually makes stitches with a single needle and always has a top thread and a bottom bobbin, a serger operates with twin needles and top and bottom looper threads. When threading a serger, it is imperative to follow the manufacturer's instructions regarding not only the correct paths the various threads must take, but also the order in which each of the threads are put through their respective paths. Even if the thread appears to be in the proper place, if the machine was threaded in the wrong sequence, the machine will not serge. Because threading a serger can be a daunting task, most machines have diagrams printed on the machines, often inside a door.

Stitch Appearance

The stitch length on a serger can be adjusted to control both the size of the straight stitches, as well as the density of the overlock stitch that encases the raw edge of the seam. A short stitch will create a seam that is nearly completely covered in horizontal, zigzag-type threads, while a longer stitch is looser and allows more of the seam and its edge to show through.

Differential Feed

The differential feed is used to control the movement of the feed dogs, the part of the machine that propels the fabric as you serge. A serger has front and rear feed dogs, which can move independently. The feed dogs normally work together, but they can be adjusted, typically with the turn of a dial, so that one feed dog moves at a different speed than the other to create smooth seams on varying weights of fabric.

Cutting

A serger has a blade that moves up and down to cut through the material as it serges. The blade is adjustable, allowing for narrow or wider seams. Many machines allow you to disengage the blade to sew without cutting the fabric. When using a serger with the blade engaged, always ensure that your fabric is not mistakenly folded under the area you are serging. If you make a mistake, you cannot simply take out the threads. You will have a hole sliced through the fabric.

Other Functions

There are many different models of sergers, some using eight or more cones of thread to complete a variety of functional tasks and decorative stitches, such as flatlock seams, pin tucking, gathering, elastic application, rolled edge hemming and invisible blind hemming.