Sewing Machine Stitch

Sewing Machine

A sewing machine is a machine used to stitch fabric and other materials together with thread. Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies. Since the invention of the first working sewing machine, generally considered to have been the work of Englishman Thomas Saint in 1790, the sewing machine has greatly improved the efficiency and productivity of the clothing industry.

Diagram of a modern sewing machine

Industrial competition

Elias Howe's lockstitch machine, invented in 1845
Elliptic sewing machine with elliptic hook and stationary bobbin, American Institute Fair, 1862
Singer treadle machine
An 1880 machine from the Wheeler and Wilson Company

Stitches

Sewing machines can make a great variety of plain or patterned stitches. Ignoring strictly decorative aspects, over three dozen distinct stitch formations are formally recognized by the ISO 4915:1991 standard, involving one to seven separate threads to form the stitch.

Plain stitches fall into four general categories: chainstitch, lockstitch, overlock, and cover stitch.

The bobbin driver of a Husqvarna3600 sewing machine

Chainstitch

Chainstitch was used by early sewing machines and has two major drawbacks:

A better stitch was found in the lockstitch. The chainstitch is still used today in clothing manufacture, though due to its major drawback it is generally paired with an overlock stitch along the same seam.The stitch is not self-locking, and if the thread breaks at any point or is not tied at both ends, the whole length of stitching comes out. It is also easily ripped out.
The direction of sewing cannot be changed much from one stitch to the next, or the stitching process fails.

A better stitch was found in the lockstitch. The chainstitch is still used today in clothing manufacture, though due to its major drawback it is generally paired with an overlock stitch along the same seam.

The basic chain stitch. Formation of the double locking chain stitch

Lockstitch

Lockstitch is the familiar stitch performed by most household sewing machines and most industrial "single needle" sewing machines from two threads, one passed through a needle and one coming from a bobbin or shuttle. Each thread stays on the same side of the material being sewn, interlacing with the other thread at each needle hole by means of a bobbin driver. As a result, a lockstitch can be formed anywhere on the material being sewn; it does not need to be near an edge.

Lockstitch utilizing a rotating hook invented by Allen B Wilson. This is employed on many modern machines

Formation of a lock-stitch using a boat shuttle
as employed in early domestic machines

Overlock

Overlock, also known as "serging" or "serger stitch", can be formed with one to four threads, one or two needles, and one or two loopers. Overlock sewing machines are usually equipped with knives that trim or create the edge immediately in front of the stitch formation. Household and industrial overlock machines are commonly used for garment seams in knit or stretchy fabrics, for garment seams where the fabric is light enough that the seam does not need to be pressed open, and for protecting edges against raveling. Machines using two to four threads are most common, and frequently one machine can be configured for several varieties of overlock stitch. Overlock machines with five or more threads usually make both a chainstitch with one needle and one looper, and an overlock stitch with the remaining needles and loopers. This combination is known as a "safety stitch". A similar machine used for stretch fabrics is called a mock safety.

A Zoje industrial overlocked

Cover stitch

Cover stitch is formed by two or more needles and one or two loopers. Like lockstitch and chainstitch, cover stitch can be formed anywhere on the material being sewn. One looper manipulates a thread below the material being sewn, forming a bottom cover stitch against the needle threads. An additional looper above the material can form a top cover stitch simultaneously. The needle threads form parallel rows, while the looper threads cross back and forth all the needle rows. Cover stitch is so-called because the grid of crossing needle and looper threads covers raw seam edges, much as the overlock stitch does. It is widely used in garment construction, particularly for attaching trims and flat seaming where the raw edges can be finished in the same operation as forming the seam.

Zigzag stitch

A zigzag stitch is a variant geometry of the lockstitch. It is a back-and-forth stitch used where a straight stitch will not suffice, such as in preventing raveling of a fabric, in stitching stretchable fabrics, and in temporarily joining two work pieces edge-to-edge.

When creating a zigzag stitch, the back-and-forth motion of the sewing machine's needle is controlled by a cam. As the cam rotates, a fingerlike follower, connected to the needle bar, rides along the cam and tracks its indentations. As the follower moves in and out, the needle bar is moved from side to side. Very old sewing machines lack this hardware and so cannot natively produce a zigzag stitch, but there are often shank-driven attachments available which enable them to do so.