Whether you enjoy repairing sewing machines as a hobby, a job, or your own business, it can be both exciting and challenging. There are so many different models and designs, it can be difficult to keep up.
When you decide to learn about sewing machine repair, there is a lot to learn. One of those things is understanding sewing machine hook systems.
When you look at a sewing machine, one of the first things you need to identify is if the machine has an oscillating or a rotary hook assembly. They do much the same task on your sewing machine, but they do it very differently.
If your machine has a rotary hook system, it will continuously turn around. Turn the hand wheel and see it rotate. The way it works, is simple. As the needle starts back up, the hooks point catches the thread in the scarf (just above the back of the eye). It then draws the thread around the bobbin.
Where do you put the bobbin on this machine? I could be inserted in front, or top under the needle plate, or on the left end of the machine. If it is a top loading bobbin, the machine is usually a rotary hook machine.
Both the front loading and side loading machines can have either hook system. A good example of the side loading machine is the popular Singer Featherweight. Bernina is famous for their front loading CB oscillating hook system, but they also produce front loading rotary systems.
A rotary hook moves around in a continuous circular motion. An oscillating hook moves back and forth. How can you tell which type of sewing machine hook assembly you have?
If you have any question, answer this. Does the hook move back and forth (Oscillating Hook) or in a complete circle (Rotary Hook)?
An oscillating hook starts out with its point up and just to the left of the needle as the needle moves down. When the needle starts up again, the hook slides behind the needle to pick up the thread from the needle. The scarf is a cut out area of the needle just above the eye which helps the thread form a loop making it easy for the point of the hook to grab the thread. The needle continues moving up while the point of hook continues moving in a half circle to the bottom. At the bottom the thread slides off the hook, and the hook makes its swing back to its starting point for the next stitch.
As far as the user is concerned, it does not matter a lot whether the machine has an oscillating or a rotary hook. Both systems achieve the same basic result. The pick up the thread from the scarf of the needle and pull it to wrap around the bobbin thread.
The movement and positioning of the hook and needle must coordinate exactly. Slight variations result in skipped stitches, poorly formed stitches, or no stitches at all. The hook and needle travel through a finite pattern. For each stitch the hook and needle must align perfectly. As the needle rises, the loop must form on the back of the needle. The point of the hook must travel to precisely the right position and at the right moment for the hook to snag the upper thread. This is called Hook Needle Timing.
Adjusting the hook-needle timing is a very common adjustment. If the user breaks a needle, sews on excessively thick material, or debris builds up in the gears; the timing often gets jolted out of adjustment. The specifics of making this adjustment vary considerably from one model to another. Some adjust on gears located directly below the hook. Some adjust at the side or at the end of the lower shaft. Some use timing belts. The essential adjustment is always the same, however, in that the point of the needle must reach the scarf at precisely the right time and in the right way. Check the specific service manual for details on adjusting the hook-needle timing until you gain enough experience and knowledge to adjust it on the fly.
The more you learn about how sewing machines work and how to repair them, the more sewing machine repair you can do. Just think there are millions of sewing machines just waiting to be serviced by somebody. You could be that somebody.
When you decide to learn about sewing machine repair, there is a lot to learn. One of those things is understanding sewing machine hook systems.
When you look at a sewing machine, one of the first things you need to identify is if the machine has an oscillating or a rotary hook assembly. They do much the same task on your sewing machine, but they do it very differently.
If your machine has a rotary hook system, it will continuously turn around. Turn the hand wheel and see it rotate. The way it works, is simple. As the needle starts back up, the hooks point catches the thread in the scarf (just above the back of the eye). It then draws the thread around the bobbin.
Where do you put the bobbin on this machine? I could be inserted in front, or top under the needle plate, or on the left end of the machine. If it is a top loading bobbin, the machine is usually a rotary hook machine.
Both the front loading and side loading machines can have either hook system. A good example of the side loading machine is the popular Singer Featherweight. Bernina is famous for their front loading CB oscillating hook system, but they also produce front loading rotary systems.
A rotary hook moves around in a continuous circular motion. An oscillating hook moves back and forth. How can you tell which type of sewing machine hook assembly you have?
If you have any question, answer this. Does the hook move back and forth (Oscillating Hook) or in a complete circle (Rotary Hook)?
An oscillating hook starts out with its point up and just to the left of the needle as the needle moves down. When the needle starts up again, the hook slides behind the needle to pick up the thread from the needle. The scarf is a cut out area of the needle just above the eye which helps the thread form a loop making it easy for the point of the hook to grab the thread. The needle continues moving up while the point of hook continues moving in a half circle to the bottom. At the bottom the thread slides off the hook, and the hook makes its swing back to its starting point for the next stitch.
As far as the user is concerned, it does not matter a lot whether the machine has an oscillating or a rotary hook. Both systems achieve the same basic result. The pick up the thread from the scarf of the needle and pull it to wrap around the bobbin thread.
The movement and positioning of the hook and needle must coordinate exactly. Slight variations result in skipped stitches, poorly formed stitches, or no stitches at all. The hook and needle travel through a finite pattern. For each stitch the hook and needle must align perfectly. As the needle rises, the loop must form on the back of the needle. The point of the hook must travel to precisely the right position and at the right moment for the hook to snag the upper thread. This is called Hook Needle Timing.
Adjusting the hook-needle timing is a very common adjustment. If the user breaks a needle, sews on excessively thick material, or debris builds up in the gears; the timing often gets jolted out of adjustment. The specifics of making this adjustment vary considerably from one model to another. Some adjust on gears located directly below the hook. Some adjust at the side or at the end of the lower shaft. Some use timing belts. The essential adjustment is always the same, however, in that the point of the needle must reach the scarf at precisely the right time and in the right way. Check the specific service manual for details on adjusting the hook-needle timing until you gain enough experience and knowledge to adjust it on the fly.
The more you learn about how sewing machines work and how to repair them, the more sewing machine repair you can do. Just think there are millions of sewing machines just waiting to be serviced by somebody. You could be that somebody.
About the Author:
Explore the essentials of repairing sewing machines Dr. David Trumble. Check out his extensive curriculum of sewing machine repair courses. Pick up your own free copy of his beginning course 7 Steps To Peak Performance For Your Sewing Machine.
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