Does Your Sewing Machine Oscillate or Rotate?
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.
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.
If the bobbin is inserted in the left end of the sewing machine arm or on the front face of the sewing machine arm, it may be either a rotary or oscillating hook.
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)?
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.
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.
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.
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.
As long as there are millions of people using sewing machines, people will need sewing machine repair. You may just be the person to meet their needs either as a hobbyist or as you own business.