overlocker

An overlocker, also known as a serger in North America, is a specialized sewing machine designed to finish fabric edges, trim seam allowances, and sew overlock stitches in a single operation. It produces clean, stretchy seams suitable for knits, and is widely used in garment construction and home sewing.

Most overlockers use two or more needles, multiple loopers, and a rotating cutting knife that trims the edge as stitches are formed. Thread configurations commonly include 3-, 4-, or 5-thread setups, each providing different finishes: a basic three-thread overlock trims and binds the edge; a four-thread setup adds a seam with an enclosed edge; five-thread machines provide a strong seam with edge finishing for knit fabrics. Some machines can create rolled hems by using a narrow stitch width.

Overlockers are typically not designed for topstitching or reverse stitching; many models lack reverse, so finishes at the ends are secured using tail threads or by finishing with a conventional sewing machine. They excel at finishing raw edges quickly and preventing frays, and are valued for reducing bulk at seams due to trimming. They are used on a range of fabrics from lightweight wovens to knits; heavier fabrics may require heavier-duty models with a higher knife clearance and more tension adjustment.

Maintenance includes regular cleaning to remove lint, oiling according to the manufacturer, and changing needles and blades as needed. Threading order and tensions must be set correctly for each fabric and stitch type. With care, overlockers deliver reliable edge finishing and contribute to professional garment construction.