I get loops on top and/or bottom of fabric during sewing. I have tried to adjust upper thread tension without any success. On brother website it is said that it might be lower tension or incorrect bobbin used. How to set lower thread tension? Thanks

If the thread is looping under the fabric, it is a top tension issue.

Make sure you are using a new needle and that the needle/thread/fabric are compatible.

Verify it is threaded correctly and that the thread is firmly seated in the tension disks.

If the top thread is still looping under the fabric, then the upper tension is too loose.

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If the thread problem appears under the fabric, it is a top thread issue.

If the thread problem appears on the top of the fabric, the bobbin thread is the issue.

Perhaps the upper thread is not seated completely in the tension disk. Remove the upper thread from the machine, ALWAYS RAISE the presser foot, then rethread from the beginning. Make sure the thread path is correct. Test your stitch.

If the thread is still looping under the fabric, the upper tension is too loose. Set the upper tension to the midway point. Test and adjust the tension until it is where you want it. Preferred tension is when both threads meet in the middle of the fabric.

sewing machine tension Google Search


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Factory standard tension for upper thread is the midway point between the high and low number. However, that tension dial is meant to be used for tweaking tension. Generally, tweaking is required whenever the type of fabric, needle, or thread are changed, ie thicker fabric like denim should have a different upper tension setting than fine chiffon. To be successful with tension settings, one must become comfortable adjusting the upper tension.

NOTE: Accurate tension is achieved when the upper thread and bobbin thread meet in the middle of the fabric.
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Understanding Bobbin Tension


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Be sure to RAISE the presser foot BEFORE threading the upper tension. This releases the tension disks so the thread will seat properly.

Start out with the upper tension set at the mid-point. This is generally the factory setting. Then test and adjust. If the thread shows loops under the fabric, the upper tension is too loose. If the bobbin thread is showing on the top of the fabric, the upper tension is too tight. Test and adjust until the top and bottom threads meet in the middle of the fabric.

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loops under fabric means top tension needs to be tightened
try cleaning the top tension dial with some unwaxed dental floss and see if that helps. if it doesn't then the tension dial may need to be replaced
also check to make sure the spool of thread is not getting caught on the spool holder
also try a new needle--one that is correct for the fabric being sewed

Loops appear on the surface (top side) of the fabric?
Reduce the tension by turning the upper tension control dial to a lower number. If the loops still appear on the surface of the fabric after you adjust the upper tension, the bobbin thread may be too loose. In this case, turn the screw clockwise, being careful not to over-tighten the screw, approximately 30-45 degrees to increase bobbin tension. After you adjust the bobbin thread, adjust the upper thread to match the bobbin thread.
Make sure you reset before your next project.

Big loops on the bottom of the fabric is NOT the lower thread. First make sure that your upper thread is correctly threaded with the presser foot in the UP position. Do a test seem. If you still have loops tighten the UPPER tension knob. Do a test seem.

If after several upper tension changes do nothing. Remove the upper thread and take some rather rough sturdy fabric like light weight denim and "floss" where the tension discs are then rethread... and try again.

Looping or bunching on on the bottom is a result of problems with the TOP TENSION.
Rethread the upper thread and adjust tension. Try again.

FYI---- Loops on the bottom-- problem is in the threading..
Loops on the top--- problem is with the bobbin.

From your description it appears that you have tried tension settings on the upper tension control adjustment knob without success.
Check that the bobin tension is adjusted correctly by taking out the bobin complete with the spool.
Pull the cotton thread and it should be a smooth light pressure if the tension is correct. If it is tight to pull or pulls freely then adjust the tension screw which is found on the outside of the bobbin. The screw is very small and requires a minature size screwdriver. The adjustment will only be a slight turn of the screw one way or the other to obtain the correct tension(depending if it was loose or tight).
Once this is set reinstall the bobin and tread up the machine, hopefully with the upper tension set at approx."2" the machine will sew correctly.