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.
A quick inspection of a sewing machine, and the technician can tell if the sewing machine hook assembly rotates or oscillates. These two types of mechanisms are very different, but perform the same basic function.
Find the bobbin on the sewing machine. Look under, around, or behind it to find the hook. Rotate the hand wheel forward and watch the hook move. How does it move? If it moves in a complete circle around the bobbin it is a rotary hook assembly. If you look closely, you can see that as the needle comes down and starts back up, the point of the hook slides behind the needle just above the eye. It picks up the thread and pulls it around the bobbin.
When you look at a sewing machine, look for where the bobbin is inserted into the sewing machine. If the bobbin is a top loading bobbin (one placed just below the needle plate and a slight bit in front of it), it is usually a rotary hook.
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.
It is easy to tell the difference. Rotary hooks rotate around the bobbin carrier in a continuous circle again and again. Oscillating hooks move to half way around and then go back to start again. The go back and forth " back and forth.
If you have any question, answer this. Does the hook move back and forth (Oscillating Hook) or in a complete circle (Rotary Hook)?
Watch closely. The point of the oscillating hook starts just a few millimeters to the left of the needle when it reaches its lowest point. As the needle rises, the hook moves behind the needle. A loop of thread forms in the small cut out on the back of the needle running above the eye called the scarf. The point of the hook grabs the thread here and pulls it around to the bottom where it releases the thread. It then oscillates back to its original position for another stitch. Bernina used their special patented CB Hook to become a premium sewing machine line.
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.
There are several ways to adjust the hook needle timing depending on the sewing machine. Some adjust the position of two interlocking gears immediately below the hook. Some must be adjusted at the right side of the lower shaft where the lower shaft joins the vertical shaft. Some must be adjusted by adjusting a timing belt. In all cases, the key is to cause the needle and hook to meet at the right time in the right way and form stitches.
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. - 15431
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.
A quick inspection of a sewing machine, and the technician can tell if the sewing machine hook assembly rotates or oscillates. These two types of mechanisms are very different, but perform the same basic function.
Find the bobbin on the sewing machine. Look under, around, or behind it to find the hook. Rotate the hand wheel forward and watch the hook move. How does it move? If it moves in a complete circle around the bobbin it is a rotary hook assembly. If you look closely, you can see that as the needle comes down and starts back up, the point of the hook slides behind the needle just above the eye. It picks up the thread and pulls it around the bobbin.
When you look at a sewing machine, look for where the bobbin is inserted into the sewing machine. If the bobbin is a top loading bobbin (one placed just below the needle plate and a slight bit in front of it), it is usually a rotary hook.
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.
It is easy to tell the difference. Rotary hooks rotate around the bobbin carrier in a continuous circle again and again. Oscillating hooks move to half way around and then go back to start again. The go back and forth " back and forth.
If you have any question, answer this. Does the hook move back and forth (Oscillating Hook) or in a complete circle (Rotary Hook)?
Watch closely. The point of the oscillating hook starts just a few millimeters to the left of the needle when it reaches its lowest point. As the needle rises, the hook moves behind the needle. A loop of thread forms in the small cut out on the back of the needle running above the eye called the scarf. The point of the hook grabs the thread here and pulls it around to the bottom where it releases the thread. It then oscillates back to its original position for another stitch. Bernina used their special patented CB Hook to become a premium sewing machine line.
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.
There are several ways to adjust the hook needle timing depending on the sewing machine. Some adjust the position of two interlocking gears immediately below the hook. Some must be adjusted at the right side of the lower shaft where the lower shaft joins the vertical shaft. Some must be adjusted by adjusting a timing belt. In all cases, the key is to cause the needle and hook to meet at the right time in the right way and form stitches.
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. - 15431
About the Author:
Discover the secrets of repairing sewing machines Dr. David Trumble. Explore 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.
