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Tensioning Problems

Tension accounts for a great deal of sewing quality issues. The most common is thread not in the tension mechanism properly, either on the bobbin case or the top tension assembly. Get to know what your tensions should feel like. When the machine is sewing well, pull on the bobbin thread and remember what if feels like. That way, you can set your bobbin thread first and just work with your upper tension.

If your tensions seems to be off do these steps first.

  • Pull on your bobbin thread - if there is no resistance then the thread has come out of the bobbin case tension. Re-thread bobbin thread holding the bobbin in place with thumb and gently tugging the thread into the proper path. Check tensions by sewing 6” seam or so on test fabric (match project fabric if possible).
  • Lower the presser foot. Pull on upper thread. There should be a lot of resistance. If there is none, the upper thread has come out of the tension assembly. Re-thread the upper thread. It is a good habit to use your thumb to hold the top thread down on the top of the machine while threading and to give the thread a tug as it passes through the upper tension assembly to ensure the thread is seated properly. Check tensions by sewing 6” seam or so on test fabric (match project fabric if possible).

Adjust the tensions so the stitching looks clean and tight and the threads meet in the middle of the fabric instead of top or bottom. Your manual will explain what to look for with your particular machine.

Do not be afraid to change your bobbin tension. I know many of you were warned of dire consequences if you did this, but it is not a problem to do so. You can always put it back to where it was. If you decide to adjust the bobbin tension you will need a small jeweller’s type flat screwdriver. Make very small adjustments with the bobbin tension as it does not take much to make a large change.

Top tension is much more forgiving. If you cannot seem to make a change it the top tension there may be a small bit of lint or thread caught in the discs. Lift your pressor foot as this will open the discs up and release the top tension. Use a small, bright flashlight to inspect the area and clean out anything seen. You can use a small fold of cloth or a pipe cleaner. Don’t use your screwdriver though as it may scratch the discs and cause more problems.

All tension assemblies can get very finicky if they are not clean so maintain them and you should have little issues. Below are some examples of tension problems.
Bird’s Nesting - This indicates you have little or no top tension. The most likely causes are the thread has missed the discs and not seated properly, the top tension adjustment is on zero, or the presser foot is up. You can see this mess if you are not securing your threads at the start of a seam. The new machines that automatically cut the thread are handy but sometimes not enough thread is left secured inside the machine and a birds nest is formed at the beginning.
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This is called ‘tunnelling’ and is seen with the ZigZag stitch. This usually means both tensions are too tight. With some lightweight fabrics, however, it may happen with even the best tension. In this case, a lightweight stabilizer may be needed under the fabric.
Proper Tension - This is what proper tension should look like from the side. Because there are 2 reasons why your thread is showing where it shouldn’t, I always tell customers to ‘know’ what your bobbin thread tension should feel like when you pull on it. That way you may only have to adjust your top tension!
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