For the beginner, setting thread tensions can be a frustrating chore, as adjustments will have to be made periodically depending upon sewing conditions. For example, as a cone of thread gets close to the end, the tension tends to change. Thus, when you start to see the physical cone itself through the windings of the thread, it should serve as a reminder to pay close attention to the quality of the stitches being formed with that particular thread. In addition, different colors of thread have different tension requirements, as the dying process can affect the surface texture of the thread. This in turn can affect how easily it flows through the thread guides. Even humidity and temperature can affect thread tensions, as well as dirt and lint buildup along the thread paths.
Bottom-line, there is no “EASY BUTTON” as tension adjustment is an ongoing process. There are devices such as tension gauges available to help you set tension correctly, but ultimately you need to learn quick, simple methods to adjust thread tensions on the fly. Most experienced embroiderers can do it by “feel”, but it takes a lot of time to develop that skill. In the meantime, we will discuss a couple of simple tricks that you can use to adjust your tensions on a routine basis.
For the upper thread, most machine manufacturers offer some type of tool which will allow you to measure the tension. Using this data, you can make adjustments and then test the results. For example, Tajima has a device that looks somewhat like an oversized ink pen with a hook on the end.
Essentially, you “hook” the thread, pull on it with the gauge and take a reading. Make any needed adjustments, then take another reading. It’s a quick and simple process that works reasonably well.
| With bobbins, you can also purchase a tension gauge which will provide you with a scientific way to measure the tension. As an alternative, you can also use the decades-old method known as the “drop-test”. It works for every make and model of machine. | | Drop Test steps - Remove the bobbin case from the rotary hook.
- Unwind the bobbin thread from the pigtail, but do not remove it from under the thread tension spring.
- Place the bobbin case, with the bobbin installed, in the palm of one hand. With the other hand grasp the end of the bobbin thread, and gently pull out about 12 inches of thread.
- Gently left up and suspend the bobbin case above the palm of your hand.
- The bobbin should not drop, but remain suspended in the air about an inch above your hand.
- Gently bob your wrist (hand holding the bobbin thread) and check that the bobbin drops a few inches then stops.
- If the bobbin does not drop, then the tension is too tight. Adjust the tension screw (the larger one) on the tension spring (clip) counterclockwise to reduce the bobbin tension. If the bobbin drops freely, then the tension is too loose. Adjust the tension screw clockwise to increase it to increase the bobbin tension.
| NOTE: IF dirt builds up under the Thread Tension Clip/Spring on the bobbin case, it will cause the tension to be too loose, no matter how much the screw is tightened. Each time you change out the bobbin, you should inspect and clean the bobbin case.
To be honest, more sewing tension problems are caused by the bobbin than the upper thread. However, since the upper thread is easier to access, more time is spent adjusting it, even though it may not be the culprit. So always pay close attention to the bobbin, even though it’s generally “out of sight, out of mind.” |
Once you have made basic adjustments to the upper and lower tension, you need to verify that both upper and lower tensions are balanced. There is a relatively simple test that will allow you to visually assess the state of the tension. Most commonly referred to as the “thirds” test, there are several slight variations of the process, but they all have the same goal: to verify the tension is balanced between upper and lower threads.
First, create a design file for sewing the letter I in a 1” tall satin block font. The concept is to have the machine sew a series of satin stitches in virtually every direction plus in a curve. Sew this on a piece of test fabric – remembering that the fabric itself can affect the tension. | Upon completion, examine the backside of the embroidery. You should see three parallel sections of thread, from left to right across each column as follows – Upper/Bobbin/Upper – in even thirds. (Thus the name “thirds” test.) (Left image)
If there is more upper thread visible than bobbin thread, then the upper thread tension is too loose, or the lower thread tension is too tight. (Center image)
If there is more lower thread visible than upper thread, then the upper thread tension is too tight, or the lower thread tension is too loose. (Right image)
A more precise test is to sew the word FOX in 1 inch, all capital, satin block. This will force the machine to sew satin stitches in virtually all directions including a curve. | | Now that you are fully armed with the knowledge to make accurate thread tension adjustments, backed up by a test (the “thirds” test) to verify balance, you are ready to take on the world, confident in your ability to ensure picture perfect embroidery on each and every job. Well, don’t get too comfortable… | | You see, the adjustments and tests are all just guidelines to help you get within the ballpark of high quality stitching. But like many of the so-called rules in this industry, the tension-setting processes are not guarantees set in stone. Ultimately, it’s the quality of the stitching that determines whether the tension settings are correct or not. In fact, you can become obsessed with trying to balance tensions to the point that it’s counterproductive. Let me show you what I mean… | | How do you identify embroiderers in a retail store that sells embroidered apparel? They are the ones looking at the backside of the garment! Of course they are trying to determine whether the company that did the embroidery had balanced tensions in order to judge whether they produce the same high quality work as themselves. These are also the same people who spend hours trying to get an equal “thirds” proportion on the backside of their own designs, without ever sewing the first garment. Unfortunately, in the quest for perfect thread balance, they have blinded themselves to the reality of thread tension: The front is always more important than the back! | The majority of the time, if the “thirds” test shows good balance, the resulting embroidery will be of high quality. But there are times when the back will not be balanced, yet the front will still be nearly perfect. As long as the backside shows proof of bobbin pickup and no bird’s nests or looping, it’s ok. In other words, don’t try to fix something that isn’t broken. If the front is good, don’t discount it because the backside doesn’t have a perfect thirds balance.
To sum it all up, use the “thirds” test to get a baseline tension setting. Then adjust as needed to achieve the best possible stitch quality on the FRONT of the embroidery, while verifying that the back of the embroidery doesn’t have any flaws that could cause the stitches to work themselves loose over time or the machine to jam up during sewing | |
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