Sewing machine timing might be compared to the elegance and grace of two ballroom dancers. Each one moves in harmony.



Following the analogy one step further, sewing machine timing may actually be more like a square dance. There are hundreds of individual parts all moving, turning, and operating all at the same time. Unless they synchronize their performances, the sewing machine fails to work. Two basic areas are concerned.

On one hand, you have the coordination of the hook and needle which perform as a couple dancing around interconnecting their threads. This is called hook-needle timing.

Second, there is the upward, backward, downward, forward motion of the feed dogs coordinating with the rise and fall of the needle. We call this feed dog timing.

Thus you can see how three key sewing machine elements must operate in complete harmony. Hook, Needle, and Feed Dogs each have numerous other parts that control and contribute to their performance. Hence, timing is everything. Without it, sewing will not result.

See the action of the feed system for yourself. Remove the presser foot. Turn the hand wheel toward you several revolutions. Watch as the needle moves and as the feed dogs move. Rotate the wheel until the needle is in its highest position. Where are the feed dogs? Right, toward the back, but still up. Advance the needle until the needle point just starts to enter the needle plate. See the feed dogs drop under the needle plate as the needle drops. By the time the needle rises again, the feed dogs have moved forward and rise with the needle.

Now check out the action of the hook and needle. Take off the presser foot, needle plate, and front cover (if a front loading machine). Find the hook and watch it in relation to the needle. Now rotate the needle all the way down. When the needle starts moving backup, the hook slides behind the needle in the middle of a cut out on the back of the needle called the scarf. When you are sewing, a loop forms that the hook picks up and draws around the bobbin to form a stitch.

The bobbin thread and upper thread wrap together. While the needle and hook proceed through their actions under the needle plate, the feed dogs move under the needle plate from back to front. The needle proceeds to rise again up out of the bobbin area exiting the needle plate. At the same time the feed dogs rise up out from under the needle plate and begin move from front to back as the needle continues to rise. The thread from the bobbin flows through a bobbin tensioner providing resistance to the thread as it is drawn up by the upper thread knot. The upper thread is also under tension from the upper tension, thread guides, tension spring, and sewing machine take up lever. The thread from top and bobbin grow increasingly tighter until they form a locked stitch in the middle of the fabric. This process is repeated for every stitch.

One of the keys to peak performance for your sewing machine is maintaining precise feed dog timing and hook-needle timing. When either or both of these are even slightly out of adjustment, the machine will fail.

Hook-needle timing controls the linking of the upper and lower threads. If it is slightly out of adjustment, the hook will fail to pick up the thread and a stitch will not be formed. This may happen intermittently, or on just one side of a zig zag stitch. Or, if the timing is out more than a few milli-meters, no stitches form.

Feed dog timing controls the movement of the fabric. If it goes out of adjustment, the fabric will not move properly. The stitches may simply pile up upon each other until they make a solid ball. While timing is critical, it is also necessary to make sure the feed dog height is properly set. If the feed dogs are too low or too high, they will not feed properly.

Like those elegant dancers, harmonious synchronized sewing machine timing is essential.