If you do machine embroidery, you surely know that proper thread tension is the alpha and omega of a nice-looking, high-quality embroidery. For beginners, setting the correct tension is often tricky, but surprisingly it can be a challenge even for experienced users.
So, what is the correct tension? You can’t simply say a specific number to be set on your machine as it may vary. Generally, the lower the number, the lower the tension, meaning the thread is looser.
If you have a combined sewing and embroidery machine, keep in mind that for embroidery the upper tension needs to be slightly looser than for regular sewing. Proper thread tension means that the upper thread isn’t loose, doesn’t form loops, and isn’t so tight that it would pull the fabric fibers. The same applies to the bobbin thread. Moreover, the threads shouldn’t be tied as in sewing, where each thread stays on its side of the fabric. In embroidery, the upper thread must be slightly pulled down to make the embroidery looking perfect on the right side, forming a rounded edge without pulling the bobbin thread to the top.
Proper thread tension looks like this on the wrong side of fabric:
The top thread is partially pulled down, so from the right side only the upper metallic thread is visible—no bobbin thread may be seen at all.
Oppositely if the tension is set incorrectly, the embroidery may look like the example on the image below. This setting not only results in higher consumption of the more expensive top thread but can also cause that the thread forms loops on the top, which doesn’t look good and what’s more important the loops may be caught by hands or other subject and embroidery then tends to unravel or get damaged very soon.
It might seem that such excessive tightening of bobbin thread could be beneficial in cases when the embroidery is visible from the back (handkerchiefs, christening blankets, towels, tablecloths, etc.), as the embroidery then looks almost the same on both sides:
But there’s still an increased risk of unraveling—just a small snag or pulled thread, and the unraveling won’t stop.
Remember, tension isn’t just adjusted for the top thread but also for the bobbin thread, even if you might be hesitant to tamper with the bobbin case. If your machine has a classic bobbin case, the tension is adjusted by turning the screw on the case.
If you embroider rather often, it’s definitely worth buying a second bobbin case where you can set the appropriate tension for embroidery and then always use that one. This way you won’t have to adjust the settings every time—just mark the cases so you don’t mix them up, for example with a drop of nail polish.
If you don’t want to buy a second bobbin case, you’ll need to remember how many turns of the screw are needed each time to adjust it back and forth. Gradually turn the screw by 90° and always check if the embroidery looks as it should. Then write down the final setting in your notebook because if you then won’t embroider for a while, you’re likely to forget it. Or, you could make marks on the bobbin case. After a few years of embroidering I bought a second bobbin case, and it was definitely worth the money. Before, when I used to change the setting each time, I would turn the screw 180° from the sewing setting. I have a small handy screwdriver by the machine, which made it easy to adjust.
For embroidery, always tighten the screw to the right because the bobbin embroidery thread is thinner, so the opening needs to be made smaller. Contrarily, the sewing thread is thicker, so you loosen the screw by turning it to the left. Handy mnemonic “righty-tighty, lefty-loosy” is helpful here.
If your machine has a top-loading bobbin, known as horizontal bobbin placement, changing the bobbin tension is more complicated. Rotary hook systems in these machines also have a screw to adjust the tension, but honestly, doing this with each change is quite a hassle.
I have this type of bobbin in my newer machines, that have automatic thread tension, so luckily, I don’t have to deal with this. Also, newer combined sewing and embroidery machines often come with two bobbin cases, but on older machines that don’t have this extra accessory, tension is only adjusted from the top. In this case, using ultra-thin bobbin thread (like KingStar) is usually excluded and the tension must be set somewhere “in between” to be acceptable for both sewing and embroidery. You then fine-tune the setting by adjusting the upper tension as needed.
Sometimes, even if you have the tension set correctly and you’ve been embroidering on the machine without any problems, suddenly the embroidery doesn’t look good. The first thing to check, of course, is whether the machine is threaded correctly or if there’s a broken thread or fiber caught somewhere along the thread path. Then thoroughly clean the machine around the bobbin case and the area under the needle plate, where clumps of dust and fibers from fabrics and threads often accumulate. But sometimes even that doesn’t help. So what could it be?
Try taking a good look inside the bobbin case. Over the time, a lot of nearly invisible dust accumulates inside the notch where the thread passes through, preventing smooth thread passage and subsequently ruining the final embroidery. Use a pin to clean it—sometimes the brush from your machine’s accessories won’t be sufficient. You also need to lift the small metal “finger” where the dirt can collect.
I must admit that even though I’ve been embroidering for a really long time, it took me years to discover this small sneaky issue.
Hope this tip will be helpful for some of you and until next time – Happy Embroidering