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Why do Sewing Machines Have Two Threads? (Explained!)

The clothes we wear contain thousands of stitches.  Just imagine how many clothes you have in your closet and how many stitches there are, it is really an amazing number of stitches. Have you ever wondered how these stitches were done?

Stitching them by hand will take months to complete and a lot of humans will be needed to meet the required number of stitches. The modern sewing machine can easily do more than 2000 stitches in a minute. It’s a marvelous wonder of modern science.

So how does a sewing machine work? Why are there two threads? Let’s demystify this & take a deeper look into this.

Why do sewing machines have two threads?

In hand sewing, One can easily stab a threaded needle through fabric and make a stitch. But when it comes to sewing with a machine, replicating the motion is quite difficult. Thus the sewing machine uses two threads, one is from the upper portion needle and a lower thread source is from the bobbin.

When you are sewing by hand, The most easy stitch will be the running stitches. You stab a needle through the cloth and go under and pull it up.

That’s pretty easy when done by hand but when it comes to sewing with a machine to replicate the similar motion is gonna be a pretty hard task. So let’s see how a machine does its stitching.

  There are three major elements on a machine that make the double stitches possible.

  • First is the needle, it will go through the fabric and it will also take the upper thread through the clothes.
  • The second is a bobbin, it will act as the lower source of the thread. The needle thread and thread from the bobbin will be looped. It will provide double threading.
  • A pressure foot alongside the needle. It will act as a clamp for the fabric, the fabric stays under the needle thanks to this.

So in the double stitches, the upper thread will be attached to the needle & the lower thread source will be the bobbin. 

The needle effortlessly goes through the fabric along with the upper thread. As the needle rises up the lower thread from the bobbin gets into a loop with the upper thread. The shuttle hook makes the loop between the upper and lower thread possible.

As the needle reaches its upper limit, the upper & lower thread will be in a tight knot, and then the stitching cycle begins again. You can control the rotational motion of your sewing machine by the foot paddle.

How to thread a sewing machine? 

The sewing machine may look different from each other but when it comes to threading the procedure is quite similar. If you learn it properly, you can do the threading in any sewing machine.

Set bobbin fully threaded: 

First set the fully threaded bobbin on the lower portion. Slide the bobbin cover, hold the end of the thread while inserting the bobbin. Just give a gentle press and it’ll set in place. Now slide the cover and you are done with the lower threading.

Spool pin: 

Now for the upper threading of your sewing machine, you will need your thread on the top spool pin. Try to keep the threads a little bit loose, shouldn’t be too much tension.

Feed through take up lever: 

And now the threads will need to go across to the thread guide grove and feed it through the take-up lever. Take the pressure foot up. Now the thread will have to go through the needle holder thread guide. Then go through the eye of the needle. 

Rotate handwheel: 

Now gently rotate the handwheel and the needle will go down to pick up the lower thread. Now make a loop between the upper and lower thread and make it go through the pressure foot. 

Take a long portion of looped thread out on the side or back. You are now all set to sew.

How do I thread a bobbin? 

So to thread a bobbin,  you will be needing a spool of thread and an empty bobbin.

  1.  Start by putting your spool of thread onto the machine spindle. 
  2. Take your thread and put it through the threads guide groove and go around the pre-tension disk. 
  3. Now stretch the threads up to the bobbin pin holder.
  4. Take the thread and put it on the bobbin.
  5. Now insert your bobbin in the bobbin pin and give a gentle press to set it properly.
  6. Now just paddle your machine and your empty bobbin will start winding up threads.

Why does my sewing machine keep breaking thread? 

Most of the time the threads get broken if there is too much tension on the threads and the thread spool ain’t set up properly. Check the thread tension, keep it a little bit loose.

Correctly set the thread spool.  Sometimes the wound of the bobbin might have a role in thread breaking. Try to keep the bobbin at 70 to 80 percent full. 

Also, check if there is any obstacle on the thread’s path, might be tangled up in any part of the grove or lever. Check if the machine threading was done properly.

If you have checked and adjusted all of these and still the thread is constantly breaking then check out the thread quality. A low-quality thread will tend to break even at a moderate tension. Try to buy a good quality thread.

Why does the thread bunch up on my sewing machine? 

There might be several reasons behind this problem. 

  • The machine is not properly threaded, the thread must haven’t set through the groove guide or the take-up lever. Recheck the threading
  • A loose bobbin thread will also create such problems. Check the bobbin thread tension.
  • The thread might have several knots or its low-quality rough texture threads. Change the thread.
  • The thread tension will also play an important part in causing this problem. Change  the thread tension and get the best thread tension by trial and error 
  • The thread spool, try to keep its end of the thread on the backside. It will be easier for the spool to release the thread this way. 

Why does the thread keep coming out of my sewing machine? 

If your threads keep coming out of your sewing machine then recheck the threading. It will be better if you thread it again and make sure not to miss any guide groove, pretension disk, and the take-up lever.

After a new threading if the thread is still coming out then it’s time to check on the thread tension. The thread shouldn’t be in too much tension or too much loose.

Try to set the perfect tension for the threads. You might have to get through some trial and error to get the perfect tension.

Now, you newly threaded your machine, got it on a perfect tension yet the thread is coming out? Then it’s time to check on the needles.

Check if it’s bent or broken or check if there is any burr on the needle. In such a case, you will have no other option but to change and get & install a new set of needles.

After going through all this if your thread is still coming out then check out the bobbin. Change thread tension. Keep it at 70 to 80 percent wound. 

Also, check the pressure foot and other related parts. You will surely get a clue on why the thread isn’t holding on.

If you still don’t have a clue on why the thread is coming out then seeking an experienced person’s suggestions or a professional opinion will help you with this.

Can you use regular thread in a sewing machine? 

You can use regular threads in a sewing machine. But you should choose the thread depending on the type of fabric you are going to use.  The thread should be able to provide proper support to the fabric after stitch. So make sure you got the right thread for the job.

What is the best thread for a sewing machine? 

There are many kinds of threads available on the market for sewing machines. You can find cotton, silk, polyester, elastic, and all-purpose thread. There isn’t any specific answer to this question. You can use cotton thread on cotton fabric, silk thread on silk fabric, and so on.

The all-purpose and polyester thread can come in handy. These are versatile and provide sufficient firmness and durability to the stitches.

At this point, you should have got a piece of in-depth knowledge on the things related to sewing machine thread and troubleshooting. 

If you get proper threading on the machines and ensure sufficient tension on the threads, you can tackle a lot of unnecessary hassle. Best of luck with your sewing.

Frequently Asked Questions:

Do Sewing Machines Need Tune Ups?

What Does a Sewing Machine Come with?

Are Sewing Machine Foot Pedals Universal or Interchangeable?

Are Sewing Machine Bobbins Universal or Interchangeable?

Are Sewing Machine Needles Universal or Interchangeable?