Bernina Sewing Machine Problems
Thinking About Your Sewing Machine Hook by David Trumble
Here is a neat hobby that can turn into a real job or even a business. I am talking about sewing machine repair. There is a special thrill when a broken down sewing machine springs back to life almost like new ” right in your hands. While there are challenges, it can also be loads of fun.
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.
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.
So to make sure what you have just answer this one question. Does it go all the way around as a rotary does, or does it go part way and retrace its path to start over as an oscillating machine does?
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.
In both cases, the action of the hook must precisely synchronize with the needle. Even slight variations cause problems. This synchronization is known as hook-needle timing. If you see skipped stitches, bad stitches, or none, check the hook-needle timing.
In about twenty percent of all standard sewing machine services, the hook-needle timing will need to be set. So, get use to this adjustment. It will be frequent. The cause of faulting timing can be traced mostly to user activity. Forcing the sewing machine to go beyond its intended use by pulling the fabric while sewing or sewing too thick a material is a common cause. Broken needles, wear and tear, Dirt, and debris are also common causes. To make this adjustment check your service manual for the model you are servicing. In time, you will gain confidence and do most adjustments without having to look them up.
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.
Get more detials on 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.
Article Source: http://www.earticlesonline.com/Article/Thinking-About-Your-Sewing-Machine-Hook/496054
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