In very simple terms a sewing machine in a needle set into a column which allows the needle to travel freely up and down. The needle is propelled up and down by a small motor contained within the casing of the sewing machine.
The sewing stitch is created by the interaction of two threads and the fabric being sewn. There are two sources of thread used in a sewing machine. The first thread is positioned at the top of the sewing machine and the thread is guided down the casing and through into the eye of the needle.
The fabric rests upon a plate in the base of the sewing machine. This plate is called the needle plate. The needle plate is a metal plate which allows the smooth running of the fabric through the sewing area. The fabric is prevented from bunching on the needle plate by two serrated wheels embedded into the needle plate and driven by another electric motor. These serrated wheels are called the feed dogs and because they are serrated they drag the fabric smoothly through the sewing area.
The second source of thread is positioned underneath needle plate. When the needle passes through the fabric together with the first thread attached it collects the second thread and then both threads are pulled back through the fabric. While this is happening the feed dogs have pulled the fabric slightly through the sewing area and the result is a small stitch is created on the fabric.
Most Common Stitches
Although many sewing machines these days have lots of dials and LCD displays and any number of built in stitches then fact remains that the vast majority of stitching done on a sewing machine is made up of two relatively simple stitches.
The first one is about as simple as they come – the material passes straight through the sewing area creating a simple straight stitch. The straight stitch is used principally for seams which means that it is the standard stitch used when making clothes.
The second most common stitch is a little stronger and as a result allows the material to stretch slightly more than occurs with the straight stitch. This stitch is called the zigzag stitch and because of its strength and pattern is great for making an attractive finish to the edges of materials. It is also good for preventing the fraying of material.
For more information about the two main stitches please watch the video below:
Other Important Parts of the Sewing Machine
To finish off, it is worth mentioning a couple of other components of the sewing machine that should have a little light shone upon them.
The presser foot is a small plate which sits on the fabric as it is pulled through the sewing area by the feed dogs. It creates a guide for the material and ensures that the material does not slip as it is sewn. The shape of the presser foot is forked and in the center of the fork the needle passes. Hence control of the fabric is right where the sewing takes place.
The final component is the foot pedal. As you might have realised by now there is quite a lot going on, even on the simplest of sewing machines. In order to ensure that there is not too much going on in the sewing area many sewing machines control the speed of the needle with the use of a foot pedal. This means that part of the sewing control is taken away from the hands area and left to the foot, in a similar manner to driving a car, the foot can act reasonably independently and safely control the speed of the sewing machine while the hands help guide the fabric through the machine.