sewing machine (thing)

A machine for sewing fabric, leather, etc. Specifically, one that uses two threads (an upper and a lower, or bobbin thread) and is best at sewing woven materials. (Another machine, a serger, is specially designed for sewing knit fabrics.)

It's hard to imagine now how revolutionary the sewing machine is. Before its invention, everything was sewn by hand. Every massive hoopskirt from the antebellum American South, every lacy shirt and brocaded coat from the court of the Sun King, every curtain in every palace, every flag, represented hours of painstaking labor. Most people had two outfits - one for working in, one for Sunday best. Now, with our closets stuffed with clothing, we take machine sewing for granted. Lucky us.

As with most innovations, the sewing machine was invented in stages.

• In 1755, Charles T. Wiesenthal of the United States patented a double-pointed sewing needle, which did not need to be turned around between stitches.
• In 1830, a Frenchman, Barthelemy Thimonnier, attached Wiesenthal's needle to a connecting rod to make a sewing machine. (I can't see how this would have worked, and I haven't been able to find more detail.)
• In 1846, Elias Howe (an American) created the lock-stitch sewing machine. This used the modern mechanism, as described below. Because the lock-stitch mechanism is the core of the function of the modern sewing machine, Howe is generally credited with its invention. However, his machine was difficult to use well, and too expensive for home use.
• In 1849, the American Benjamin Wilson introduced an automatic feeding mechanism, which solved the main usability problem with Howe's machine.
• In 1851, Bostonian Isaac Meritt Singer patented two refinements to the sewing machine: a fixed arm structure still used today, and the presser foot. He began manufacturing a sewing machine priced for home use. His company, Singer, is still the largest sewing machine manufacturer in the world.

The sewing machine predates electricity. Early machines used a hand crank or a treadle to drive them. These turned out to be easily electrified, and many are still in use today.

Later innovations (apart from electricity) include the ability to zigzag and to make more sophisticated stitching patterns. The latest machines have LCD screens, microprocessors, and pre-programmed fonts for monogramming. (All cute, but unnecessary).

To describe machine sewing, we should start with a review of hand sewing. Hand sewing, of course, uses a needle with the eye at the back to draw a thread through fabric. This requires the needle to be pulled entirely through the fabric, turned around, and pulled through in the other direction.

Machine sewing does none of that.

Here's a diagram to help you visualize.

                ___________|_  <- spindle for the spool of thread
              /              |-
 fixed arm -> |    ______    | | <- manual advance 
              |___|     |    |-
   needle* ->  _|_      |    |
base plate -> __________|    |
             |  O            | <- the O is the bobbin assembly
             |_______________| 

The needle has its eye at the sharp end. The other end is attached to a rod that goes up and down inside a fixed arm. The arm also holds a presser foot, which can be raised or lowered manually, but which is kept down when sewing. Its role is to press the fabric against a base plate. The needle plunges into the fabric from the top, through a hole in the presser foot. There is a thread which goes from a spool, through a thread tensioning mechanism, and through the eye of the needle.

There is another thread, which comes up from under the fabric being sewn. This is the bobbin thread, which was wound onto its bobbin before sewing. The bobbin sits in a bobbin case, which is not fixed to the sewing machine case. It floats in its own casing (this is important).

To begin sewing, the needle plunges through the fabric, taking a loop of the top thread with it. Here's the clever bit. A small hook on the bobbin case catches the needle thread. The bobbin case rotates, effectively passing the entire bobbin through the loop of top thread. This twists the bobbin thread with the top thread, making the stitch. The needle is then pulled back up. If your thread tension is correct, the twist between the top and bobbin threads is pulled into the fabric you're sewing as it goes.

       \        /    <- upper thread
________\______/____ top layer of fabric
        -\-----
       /  ---/ \
______/_________\___ bottom layer of fabric
     /           \   <- bobbin thread

Once the needle is out of the way, the feed dogs, which are located in the base plate, push the fabric up against the smooth underside of the presser foot. As they then slide backward, they push the fabric with them to make a visible stitch.

There is also a backstitch lever on the machine. When that is pressed, everything happens as described above except that the feed dogs push the fabric toward you rather than pulling it away from you.

Thread the bobbin (RTFM - bobbin winding varies too much to describe here). Put it in the bobbin casing, and thread the machine. Place the fabric in under the needle, and lower the presser foot. Push the pedal or the knee control.

Of course, it isn't really that simple. It takes practice, like any manual skill. Here are a few top tips.

• Thread it correctly. Different makes of machine have different threading patterns. RTFM, or get someone who knows to show you. Most of the people who work in fabric stores know a lot about sewing, and would be able to advise you.
• Adjust your thread tension, stitch length, and stitch width correctly.
• Practice on scrap fabric before you do any serious sewing. Learn to control the path of the stitching, and the speed of the machine (it can really run away with you)
• Backstitch at the beginning and end of each seam.
• Never, never turn the manual advance (the knob in the upper right) clockwise. It always goes counter-clockwise.
• Never force the machine.
• Don't pull the fabric through the machine - let the feed dogs do the work.