Sewing machine repair is an exciting and satisfying career , but it is also a great hobby or business. While, repairing sewing machines is not for everyone, it can be lots 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.

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.

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?

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?

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.

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.

When you consider that there are almost 90,000,000 sewing machines in use today, there are a bunch of sewing machines to service and repair. Sewing machine repair makes a great hobby or business.