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 start tinkering with sewing machines, be ready to learn loads of information. There are literally thousands of different models and designs, but there are also some obvious similarities. One of the tricky areas of interest is the hook assembly.
There are two basic types of hook assemblies: The Rotary Hook assembly and the Oscillating Hook assembly. Each type has its own features and benefits, but they both do essentially the same job.
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.
The bobbin may be installed just under the needle from the top, on the left end, or on the front lower arm of the machine. If the bobbin inserts from the top, it normally has a rotary hook.
A bobbin installed on the left side of the sewing machine may either have a rotary hook or an oscillating hook. The same is true of front loading sewing machines. For example, while Bernina sewing machines became famous for the CB Oscillating Hook System with front loading, they continue to use front loading on the high end rotary hook sewing machines.
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)?
The Oscillating Hook Assembly involves a hook that begins a few millimeters to the top left and moves to the right sliding behind the needle and past it around to the bottom of the swing. Then the hook travels back again the same way to its original position for a return oscillation. Bernina sewing machines built their superior reputation based on their advanced oscillating hook system called a CB Hook.
Oscillating and Rotary hook systems do the same job. That job is pulling the thread from the needle around the bobbin carrier. The point of the hook slides behind and through the scarf of the needle to get the thread. Then it carries it to its destination.
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. - 16732
When you start tinkering with sewing machines, be ready to learn loads of information. There are literally thousands of different models and designs, but there are also some obvious similarities. One of the tricky areas of interest is the hook assembly.
There are two basic types of hook assemblies: The Rotary Hook assembly and the Oscillating Hook assembly. Each type has its own features and benefits, but they both do essentially the same job.
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.
The bobbin may be installed just under the needle from the top, on the left end, or on the front lower arm of the machine. If the bobbin inserts from the top, it normally has a rotary hook.
A bobbin installed on the left side of the sewing machine may either have a rotary hook or an oscillating hook. The same is true of front loading sewing machines. For example, while Bernina sewing machines became famous for the CB Oscillating Hook System with front loading, they continue to use front loading on the high end rotary hook sewing machines.
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)?
The Oscillating Hook Assembly involves a hook that begins a few millimeters to the top left and moves to the right sliding behind the needle and past it around to the bottom of the swing. Then the hook travels back again the same way to its original position for a return oscillation. Bernina sewing machines built their superior reputation based on their advanced oscillating hook system called a CB Hook.
Oscillating and Rotary hook systems do the same job. That job is pulling the thread from the needle around the bobbin carrier. The point of the hook slides behind and through the scarf of the needle to get the thread. Then it carries it to its destination.
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. - 16732
About the Author:
Get more detials on 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.
