Skipped Stitches on a Sewing Machine: Why Does It Happen? How Do I Avoid It?

What to do when your machine skips stitches
The function of your sewing machine is to tie a knot between the top thread and bobbin thread. When the machine fails to tie a knot, you get a skipped stitch. In order to understand why a machine produces skipped stitches, one must first understand how a sewing machine makes a good stitch in the first place.
As a sewing machine runs, it makes continuous revolutions. 1 stitch requires 1 revolution. So, if your machine makes 10 stitches, it has completed 10 revolutions. If you turn over the hand-wheel on your machine and watch the needle, you can map the machine’s revolution. As you turn the hand-wheel, the needle travels down below the needle plate, then up above the needle plate. Note that as the needles goes up and down, there is point where the needle is at its highest position and a point where the needle is at its lowest position. Once the needle reaches its lowest position, it begins to move upwards again.

Now imagine your needle is threaded and is in the highest position above the needle plate. As you begin to sew, the needle travels downwards with the top thread. The needle pierces the fabric and travels down below the needle plate. Eventually it reaches its lowest position. As it begins to move upward again, the thread forms a loop at the eye of the needle. As the loop is formed, the machine’s hook travels directly above the eye of the needle and catches the thread loop. Then the hook makes a revolution around the bobbin. During the hook’s revolution, a knot is formed between the needle thread and the bobbin thread. This knot is eventually cinched by the action of the take-up lever, which occurs as the needle reaches its highest.

I realize there is a lot going on in what was just said. To get a better visual of the hook passing directly above the needle eye, watch the following videos:
CB Hook System (Oscillating Hook) on Bernina 335
Rotary Hook System on Bernina 560
To get a better visual of the hook catching the thread loop formed at the eye of the needle, watch the following video:

Sewing machine hook passes above eye of needle, catches thread loop
That sums up the very basics of how a sewing machine forms a stitch. So, what causes skipped stitches?

Skipped stitches typically occur when the sewing machine hook fails to catch the upper thread loop formed at the needle’s eye. Remember that the hook point must pass directly above the needle eye in order to catch that loop. But what if it fails to do so? What if it passes too far above/below the eye, or too far a distance away from the eye? In each of these situations, the hook will not catch the loop, and there will be a skipped stitch.

There are a multitude of reasons why the hook is not passing directly over the eye of the needle. If the hook is passing too high above the needle eye or too far below the needle eye, then there is a possibility that your machine is out of time. Remember that your machine has been engineered so that the needle’s revolution and the hook’s revolution are in sync with each other. If these two parts ever go out of sync, your machine is out of time and you get skipped stitches.

Another possibility is that a critical setting called needle-hook clearance is out of whack. When the hook passes behind the needle, it is set as a specific distance away from the needle. It is not so close that the hook and needle touch, but it is not so far away that the hook misses the thread loop. If the needle-hook clearance is too large– meaning that the hook passes too far away from the back of the needle to catch the loop– then you will see skipped stitches.

It is possible that your machine is skipping stitches because your machine is out of time. It is possible that your machine is skipping stitches because the needle-hook clearance is off. However, neither of those are the most likely reason for skipped stitches. The majority of the time, a machine will skip stitches simply because of a bent needle.

Think about it. If the needle is bent to the left or the right, then the hook will not pass directly above the eye of the needle like it is supposed to. If it is bent forward or backward, then the needle-hook clearance will be off. Therefore, it might seem like one of these critical settings is out of whack and your machine needs to come into the shop for repair. However, more often than not the reality is that your needle is bent. You don’t necessarily need to bring your machine into the shop. You just need to change your needle.

So, what do you do when your machine skips stitches?

First change your needle and see if that solves the problem.
We hope this has been informative and helps you better understand your machine. If you ever have any issues with your machine, please do not hesitate to reach out to us. Give us a call or stop by the shop so we can help fix your problem and get you back to sewing.
Call us at (925)937-7575 for more information.
Our hours are 9AM-5PM Tuesday-Saturday
And don’t forget to tell your friends!
Sewing Machine Shop
1661 Botelho Drive, Suite 180
Walnut Creek, CA 94596
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