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What you must know about thread tension

What you must know about thread tension

What is thread tension?

Thread tension is the amount of tension applied to the embroidery thread during the embroidery process.

Simply put, you can think of it as the degree of tightness or looseness of the embroidery thread during embroidery.

Specifically, it can be categorized into top thread tension and bottom thread tension. The principle of embroidery is that the top and bottom threads are hooked together by the needle and this process is repeated over and over again to form a complete pattern. During this process, the forces of the top and bottom threads pulling against each other will work together to form the embroidery.

Embroidery thread tension is an unavoidable issue when using an embroidery machine. Keeping the machine at the right tension is important to accomplish beautiful embroidery work and increase the speed of it.

In this blog, we will explain in detail about embroidery thread tension to help you deepen your understanding of it, so that you can solve problems caused by tension faster.

How to know if the thread is at the right tension?

This means that the bottom thread is in no view on the front of the fabric, there are no floating threads on the surface and the bottom thread is about 1/3 on the back is optimal for normal embroidery.

If the thread tension is not right, problems such as thread breakage, bird's nests, and uneven embroidery can occur. These problems can greatly hinder the embroidery process and increase costs.

So, if the tension is not right, how to check and adjust it?

#1 Check threading

Make sure that the embroidery machine is threaded correctly before making any looseness adjustments. Each step is important. Sometimes incorrect threading can cause thread looseness problems.

For more information on how to properly thread, please check out these two videos.

#2 Adjusting the large screw on the bobbin case

Turn the screw counterclockwise to loosen and clockwise to tighten. When the bottom thread of the pattern is too full and the bobbin is too loose, you can adjust it by rotating the big screw on the bobbin case clockwise; when the bottom thread of the pattern is too sparse and the bobbin is too tight, you can adjust it by rotating the big screw on the bobbin case counterclockwise.

#3 Adjusting the Tightening Knob

When adjusting the bobbin case, you can also adjust the corresponding knob for the needle currently being used.

  • If there is bottom thread being pulled out of the fabric surface, the knob should be turned looser to the left. 
  • If there is thread throwing on the surface, the knob should be adjusted to the right to tighten. 
  • One and a half turns of the upper knob is one unit of adjustment, and one half turn of the lower knob is one unit of adjustment.

For those with experience, it's still mostly experience that counts when adjusting tension. If you are a novice, it is recommended that you use a tension tester to confirm that the thread tension is in the proper range. You can refer to the values in the table below.

#4 Adjust The Spring Lever

Sometimes a small change in the spring lever may regulate the looseness or tightness on the embroidery work. If the spring lever is all the way up, the threads will be too loose for all needles to work properly. On the contrary, if the spring lever is placed to the bottom, the threads will be too tight for all needles.

The spring lever controls the looseness or tightness of all the needles of the machine, and it should be positioned directly in the center, at 90°.


It is important to notice that the reasons for embroidery problems are varied. If you find that the problem remains after adjusting the tension settings, it's time to consider other influencing factors. For example, the embroidery speed is too fast, the design of the embroidery plate is not reasonable, the machine maintenance is not good, and other factors may also cause the embroidery process to be unsmooth, which you need to eliminate one by one.

Of course, you can also contact our technicians for help, they are ready to help you 24 hours. In addition, you can also join our Facebook community  to connect with other experienced embroiderers!

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