How Sewing Machines Work

By: Tom Harris & Yara Simón  | 
Woman sewing fabric on sewing machine
A standard electric sewing machine is an amazing piece of technology. Michael Haegele / Getty Images


Without the sewing machine, the world would be a very different place. Like the automobile, the cotton gin and countless other innovations from the past 300 years, the sewing machine takes something time-consuming and laborious, like turning raw seam edges into tidy hems, and makes it fast and easy.


With the invention of the mechanical machine, manufacturers could suddenly produce piles of high-quality clothing at minimal expense. Because of this technology, the vast majority of people in the world can now afford the sort of sturdy, finely stitched clothes that were a luxury only 200 years ago.

As it turns out, the automated stitching mechanism at the heart of a sewing machine is incredibly simple, though the machinery that drives it is fairly elaborate, relying on an assembly of gears, pulleys and motors to function properly. When you get down to it, the sewing machine is among the most elegant and ingenious tools ever created.


History of the Sewing Machine

The origins of the sewing machine trace back to at least the early 19th century. While there were previous attempts to mechanize sewing, it was the work of several inventors that led to the development of the sewing machine as we know it today.

Decades after Thomas Saint patented a sewing machine in the late 1700s, French tailor Barthélemy Thimonnier created one of the first practical machines. Used to create uniforms for the French army, his machine used a hooked needle and a single thread to create a chain stitch.


Following Thimmonnier’s contributions, Walter Hunt invented a locksmith sewing machine in 1834, but he did not patent his design. It was inventor Elias Howe who obtained a patent for a locksmith sewing machine in 1846. Howe’s machine used two threads and a shuttle mechanism, allowing for a stronger and more efficient stitch.

By the 1850s, businessman Isaac Singer played a crucial role in popularizing the sewing machine. In 1851, he improved upon Howe’s design and patented his own machine, which incorporated a friction pad, a way to make the stitch tighter and an adjustable arm.


Evolution of the Sewing Machine

The look of the sewing machine has undergone many changes since the 1700s. As technology advanced, computerized sewing machines emerged, offering programmable stitch patterns and automated features. Today, sewing machines have become more versatile, incorporating specialized functions like quilting and embroidery.

The introduction of advanced features such as LCD screens, automatic thread cutters and precise stitch control has improved the sewing process. This continuous evolution has made sewing machines more efficient, user-friendly, and capable of producing intricate and professional-quality stitches.


From Singer to Brother to Janome, there are hundreds of sewing machine models on the market. At the low end of the scale, there are conventional, no-frills electric designs, ideal for occasional home use; at the high end, there are sophisticated computerized sewing machines and specialty quilting machines. But despite what model works best for you, most sewing machines are built around one basic idea: the loop stitching system.

The Loop Stitch

The loop stitch approach is very different from ordinary hand-sewing. In the simplest hand stitch, a length of thread is tied to a small eye at the end of a needle. The sewer passes the needle and the attached thread all the way through two pieces of fabric, from one side to the other and back again. In this way, the needle runs the thread in and out of the fabric pieces, binding them together.

While this is easy enough to do by hand, it is extremely difficult to pull off with a machine. The machine would have to release the needle on one side of the fabric just as it grabbed it again on the other side. Then it would have to pull the entire length of loose thread through the fabric, turn the needle around and do the whole thing in reverse. This process is way too complicated and unwieldy for a simple machine, and even by hand it only works well with short lengths of thread.


Instead, modern sewing machines pass the needle only partway through the fabric. On a machine needle, the eye is right behind the sharp point, rather than at the end.

The needle is fastened to the needle bar, which is driven up and down by the motor via a series of gears and cams (more on this later).

When the point passes through the fabric, it pulls a small loop of thread from one side to the other. A mechanism underneath the fabric grabs this loop and wraps it around either another piece of thread or another loop in the same piece of thread.

There are actually several different types of loop stitches, and they all work a little differently.


Chain Stitch

The simplest loop stitch is the chain stitch. To sew a chain stitch, the sewing machine loops a single length of thread back on itself.

The fabric, sitting on a metal plate underneath the needle, is held down by a presser foot. At the beginning of each stitch, the needle pulls a loop of thread through the fabric.


A looper mechanism, which moves in sync with the needle, grabs the loop of thread before the needle pulls up. Once the needle has pulled out of the fabric, the feed dog mechanism (which we'll examine later) pulls the fabric forward.

When the needle pushes through the fabric again, the new loop of thread passes directly through the middle of the earlier loop. The looper grabs the thread again and loops it around the next thread loop. In this way, every loop of thread holds the next loop in place.

The main advantage of the chain stitch is that it can be sewn very quickly. It is not especially sturdy, however, since the entire seam can come undone if one end of the thread ends up loosened. Most sewing machines use a sturdier stitch known as the lock stitch.


Shuttle Hook and Bobbin

The most important element of a lock-stitch mechanism is the shuttle hook and bobbin assembly. The bobbin is just a spool of thread positioned underneath the fabric. It sits in the middle of a shuttle, which is rotated by the machine's motor in sync with the motion of the needle and the upper thread.

Just as in a chain-stitch machine, the needle pulls a loop of thread through the fabric, rises again as the feed dogs move the fabric along, and then pushes another loop in. But instead of joining the different loops together, the stitching mechanism joins them to another length of thread that unspools from the bobbin.


When the needle pushes a loop through the thread, the rotary shuttle grips the loop with a hook. As the shuttle rotates, it pulls the loop around the thread coming from the bobbin. This makes for a very sturdy stitch.

Sewing Machine Components

The conventional electric sewing machine is a fascinating piece of engineering. If you were to take the outer casing off, you would see a mass of gears, cams, cranks and belts, all driven by a single electric motor. The exact configuration of these elements varies a good deal with the different sewing machine brands, but they all work on a similar idea.

  • The electric motor connects to a drive wheel by way of a drive belt.
  • The drive wheel rotates the long upper drive shaft, which connects to several different mechanical elements.
  • The end of the shaft turns a crank, which pulls the needle bar up and down. The crank also moves the thread-tightening arm.
  • Moving in sync with the needle bar, the tightening arm lowers to create enough slack for a loop to form underneath the fabric, then pulls up to tighten the loop after it is released from the shuttle hook.
  • The thread runs from a spool on the top of the machine, through the tightening arm and through a tension disc assembly. By turning the disc assembly, the sewer can tighten the thread feeding into the needle. The tension must be tighter when sewing thinner fabric and looser when sewing thicker fabric.
  • The first element along the shaft is a simple belt that turns a lower drive shaft. The end of the lower drive shaft is connected to a set of bevel gears that rotates the shuttle assembly. Since both are connected to the same drive shaft, the shuttle assembly and the needle assembly always move in unison.
  • The lower drive shaft also moves linkages that operate the feed dog mechanism. One linkage slides the feed dog forward and backward with each cycle.
  • At the same time, another linkage moves the feed dog up and down. The two linkages are synchronized so that the feed dog presses up against the fabric, shifts it forward and then moves down to release the fabric.
  • The feed dog then shifts backward before pressing up against the fabric again to repeat the cycle.
  • The motor is controlled by a foot pedal, which lets the sewer vary the speed easily. The cool thing about this design is that everything is linked together, so when you press on the pedal, the motor speeds all of the processes up at the same rate. The process is always perfectly synchronized, no matter how fast the motor is turning.


Computerized Sewing Machines

One important addition to this basic design is the ability to sew different sorts of stitches, such as an overlock stitch. The typical stitch options for conventional mechanical machines are variations on the zigzag stitch. The zigzag stitch is exactly what it sounds like: a stich with a jagged line.

This zigzag stitch, which is a good choice for stretchy material, is fairly simple to achieve. All you have to do is move the needle assembly from side to side at the same time that it is moving up and down.


Conventional Electric Sewing Machine

In a conventional electric machine, the needle bar is attached to an additional linkage, which is moved by a cam on the main drive shaft. When the linkage is engaged, the rotating cam shifts the linkage from side to side. The linkage tilts the needle bar back and forth horizontally in synch with the up and down motion.

Modern Sewing Machines

Things work a little differently in the modern machine. Today's higher-end machines have built-in computers, as well as small monitor displays for easier operation.

In these models, the computer directly controls several different motors, which precisely move the needle bar, the tensioning discs, the feed dog and other elements in the machine. With this fine control, it is possible to produce hundreds of different stitches.

The computer drives the motors at just the right speed to move the needle bar up and down and from side to side in a particular stitch pattern. Typically, the computer programs for different stitches are stored in removable memory disks or cartridges. The sewing machine computer may also hook up to a PC in order to download patterns directly from the Internet.

Specialized Embroidery Machines

Some electronic sewing machines also have the ability to create complex embroidery patterns. These machines have a motorized work area that holds the fabric in place underneath the needle assembly. They also have a series of sensors that tell the computer how all of the machine components are positioned.

By precisely moving the work area forward, backward and side to side while adjusting the needle assembly to vary the stitching style, the computerized machine can produce an infinite number of elaborate shapes and lines. The sewer simply loads a pattern from memory or creates an original one, and the computer does almost everything else. The computer prompts the sewer to replace the thread or make any other adjustments when necessary.

Obviously, this sort of high-tech sewing machine is a lot more complex than the fully manual sewing machines of 200 years ago, but they are both built around the same simple stitching system: A needle passes a loop of thread through a piece of fabric, where it is wound around another length of thread. This ingenious method was one of those rare, inspired ideas that changed the world forever.


19 Types of Sewing Machines

Before you look for a first sewing machine or a specialized machine for more advanced projects, it's important to know what each is capable of achieving. Available from different brands and with the ability to work with stretchy fabrics and help with garment construction and detail work, here are multiple types of machines that you should know before you embark on your sewing journey.

1. Mechanical Sewing Machine

This standard machine is operated manually with mechanical controls for stitch length and width adjustments. It does not have as many built-in stitches as other models. This machine is optimal for beginner sewists as a first machine as well as those of an advanced skill level.


2. Computerized Sewing Machine

Also known as overlock machines, these technologically advanced machines have electronic controls, programmable stitch patterns and an LCD screen for easy customization.

Computerized sewing machines can make the stitching process easier through automated stitch selection, precise stitch control, programmable stitch patterns, an automatic thread cutter and stitch adjustment and editing.

3. Serger Sewing Machine

Also known as an overlock machine, this machine trims and finishes fabric edges simultaneously while creating professional-looking seams.

4. Embroidery Machine

Specifically designed for intricate embroidery work, it features built-in embroidery designs and can stitch complex patterns automatically.

5. Sewing and Quilting Machine

Designed for quilting projects, it offers a larger sewing surface, adjustable stitch length and a wide variety of quilting stitches.

6. Industrial Sewing Machine

Built for heavy-duty use in commercial settings, it provides high-speed stitching and can handle thick or tough fabrics and multiple layers that most machines cannot handle.

7. Portable Sewing Machine

Lightweight and compact, it is easily transportable and suitable for on-the-go or small-scale sewing projects.

8. Handheld Sewing Machine

This small, battery-operated device works for quick repairs and stitching on-the-spot, making it ideal for small jobs and travel.

9. Cylinder Bed Sewing Machine

This machine features a cylindrical bed that allows sewing in circular or cylindrical items such as cuffs, sleeves, and bags.

10. Blind Hem Sewing Machine

Specifically designed for creating invisible hems, it uses a special foot and stitch to achieve seamless, nearly invisible finishes.

11. Coverstitch Machine

Primarily used for hemming and topstitching knitted fabrics, it produces a professional-looking coverstitch on the top with a double or triple row of stitches on the underside.

12. Buttonhole Machine

Designed to automate the buttonhole-making process, it creates precise and consistent buttonholes with the touch of a button.

13. Leather Sewing Machine

Built with heavy-duty components, it has the strength and durability needed to sew through thick and tough leather materials.

14. Multi-needle Embroidery Machine

This kind of machine enables simultaneous stitching with multiple needles, allowing for faster embroidery production and intricate design possibilities.

15. Long-Arm Quilting Machine

Designed specifically for quilting large projects, it features an extended arm that allows for easier handling and maneuvering of bulky quilts.

16. Button Sewing Machine

Designed specifically for attaching buttons to garments, it automates the button-sewing process for efficient and precise results.

17. Chain-stitch Machine

This sewing machine creates a series of looped stitches that resemble a chain and is commonly used in decorative stitching or for seaming and hemming lightweight fabrics.

18. Zigzag Sewing Machine

This type of sewing machine provides the ability to create zigzag stitches, essential for stretch fabrics, appliqué work and decorative stitching.

19. Hand Crank Sewing Machine

Operated manually with a hand crank, it is a vintage-style machine popular among sewing enthusiasts and collectors.


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This article was created in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.