Types of Sergers Sergers cannot totally replace the traditional sewing machine. They are designed to be used in addition to or in combination with a regular machine. Learning how and when to use a serger with your conventional machine is the key to successful sewing. The two thread has one needle and uses two spools of thread. The two-thread stitch is primarily used as a seam or edge finish and is not designed to stitch a regular seam.
Some machines can do a two-thread narrow rolled hem.
The two-thread stitch also is used to do a flatlock seam where two fabric layers are stitched, then pulled apart so the seam allowances are flat inside the stitching. The three thread has one needle and uses three spools of thread. It is considered a versatile and commonly used serger for home sewing. The three-thread stitch is used as a seam and as an edge finish. As a seam, it is suitable for woven fabrics, but in areas of stress, stitching should be reinforced with a conventional machine.