singtopraya (@singtopraya)
Jan 22nd 2019, 7:34 pm

Sewing machine tension problems rank within the top three user complaints. It does not matter whether the machine itself is a cheap dime store machine or if it is an elegant high quality machine. When the sewing machine tensions are mess up, it can be extremely aggravating. Excess threads may bubble up on top of the fabric, or it may bunch up hidden underneath. In either case, learning to adjust the tensions properly is essential.

There are many possible causes of bad sewing machine tension. One of the common causes of improper tension comes from faulty threading of the upper thread or bobbin assembly. Missing a thread guide, threads floating on top of the upper tension discs, or threads missing the bobbin tension can cause havoc with the stitch quality. Rough spots, worn surfaces, lint and debris, burrs on the hook, bad needles, and bad thread can also cause faulty tension.

Properly set tensions should produce stitches with the upper and lower thread locked together in the center of the fabric. When you look at the seam from the top side, you should see a smooth even flow of thread with tiny holes into the fabric. When you turn the fabric over, you should see exactly the same quality stitching as you saw from the top side. The stitches should be snug and show no extra threads on top or bottom.

Tension is simply the resistance created by the sewing machine to guide and manipulate the thread making it do what it is intended. When this resistance is adjusted correctly, the upper thread and lower thread mechanism balance each other. The result is a quality stitch without excess threads where they should not be.

If you think of the top and bottom thread systems like two tug of war teams, it may help us understand what is actually happening. Each team pulls on their rope. If one team pulls harder than the other, it gets more rope on its side. If the other team pulls harder, it gets the extra rope. In this case, we are talking about thread instead of rope, but the analogy still applies. Therefore, if you see extra thread on top of the fabric, what do you know? Yes, the upper thread system is pulling harder than the lower one. Or the lower one is pulling less than the upper one. In the same way, if you see excess thread on the bottom what do you know?

Adjusting the tensions on your sewing machine is usually quite easy once you understand what your tension system is suppose to do. Your goal is to modify the drag on the thread until the resistance is equalized top to bottom " bottom to top.

Begin your corrective efforts by rethreading the upper thread. Be intentional and careful to insure everything is just right. Remember to lift the presser foot while threading. Watch out for anything that might snag the thread. Check to make sure not lint or gunk has messed gotten stuck between the tension discs. Watch out for rough spots. Once you reach the needle, gently draw on the thread two or three inches. You should feel very little resistance. The thread should flow smoothly. Now drop the presser foot, and test again. Is there more resistance? Good.

Take your bobbin out. Is the thread wound evenly? It should be. Place it back in its carrier. Check the tension spring for any debris or lint that may have collected under it and clean it out. Slide the thread under the tension spring. Test it to make sure there is moderate resistance on the thread. This usually does not require adjustment unless you change the size of thread significantly. Some suggest that a professional sewing machine repair person make these adjustments when needed.

Finally, tighten the upper tension until it balances the lower tension providing stitches that meet in the middle of the fabric. Test and retest. Keep in mind the numbers on you upper tension do not really mean much. The key is to balance the resistance.

Always do a test seam on scrap materials before sewing a finished seam that will be seen. Adjust the tension on the stitch you plan to use until it is properly balanced. Note a straight stitch may appear balanced, but when you go to a zig zag or other stitch, it may not produce your perfect stitch. Always test before sewing your finished seam.

Sometimes things just do not work perfectly. The thread, the needle, the fabric, and the machine can all contribute to small challenges. Some of these issues can be resolved by using better thread, replacing the needle, using the right needle, or using better fabric. If you have good tension with straight stitches, but one side of the zig zag is still not just right. Minimize the flaws by setting tensions to keep the flaw on the underside instead of the facing side of the fabric. Narrowing and shortening the zig zag stitch can also help.

When you understand how your sewing machine tensions work, you can adjust them with confidence. In those rare instances where your best efforts fail, you can always rely on your local sewing machine repair technician.