The best indication of your sewing machine having balanced tensions is the absence of any wobbles, loops, and puckers, excess of thread on top or bottom with the thread going straight along the seam.
If the tensions are not proper you get irritated as every time you try to sew, the thread gets messed up. One frequent complaint that users of sewing machines have is about the quality of stitch as a result of improper tension.
One feels that poor sewing machine tensions cause severe user tensions. The sewer continues to believe all is fine, but surely gets upset on turning the fabric over and noticing gobs of ugly tangled threads. At times the thread may pucker up in tiny balls on top of the fabric.
There can be many reasons for unbalanced tension of sewing machine. Threading is a common problem. You must have threaded your sewing machine many times, but once the thread misses a guide or rides along the ridge of the tension discs, you have problems at hand.
Tensions get misaligned due dirt, gunk, grit, rough spots, irregular surfaces, rust and burrs. The other reasons that could cause problem of tension include: loosely wound bobbins, dull needles, bad thread, and of course mechanical failures.
Correct adjustment of tensions delivers stitches with the upper and lower thread locked together in the middle of the fabric. As you check the seam from the top side, there should be a smooth even flow of thread with tiny holes into the fabric. And, on turning the fabric over, again you should have exactly the same quality of stitching as you found on the top side. The stitches should be snugly placed without any extra threads on top or bottom.
There should not be visible any loops of thread, intertwined thread tails, puckers, gobs of unsightly threads or skipped stitches.
The tension system of a sewing machine is designed to create drag or resistance which we call tension. When it is properly adjusted, the upper and lower thread tensions are equalized to produce proper stitches. If it’s perfectly adjusted you won’t find any extra thread anywhere.
You should understand that a sewing machine necessarily incorporates an arrangement that pulls the thread up. Simultaneously, it has another arrangement beneath its needle plate that pulls the thread down. Bothe the actions are taking place all the time when the machine is in operation. So, if the pull on the upper side is stronger than the one on the lower side, you get little puckers, wobbles, or balls of thread on the top of the fabric. On the other hand if the pull is more from the underside, you get bunches of tangled threads beneath the fabric.
Only when the pull from either side is equal, you get a proper stitch devoid of excess threads. That’s a sure indication that the tensions are balanced. So you should aim to provide equal tension from the upper and lower threads. Start taking corrective measures by re-threading the upper thread.
Be alert and careful. Ensure to lift the presser foot while threading. Watch out for anything that could holdup the thread. Ensure that there is no lint or any foreign matter stuck between the tension discs. Be wary for rough spots. As you reach the needle, gently draw two to three inches of thread. You should feel slight resistance. The thread should flow smoothly.
Next, drop the presser foot, and test again. You should feel more resistance. Take the bobbin out and check that the thread is evenly wound.
Keep it back in its carrier. Check the tension spring and remove any debris or lint that might have collected beneath it. Glide the thread under the tension spring. Check to ensure that there is moderate resistance on the thread. Normally it won’t need adjustment unless you change the size of thread drastically. Some like to trust a professional sewing machine technician to make these adjustments whenever required.
Finally, adjust the upper tension till it balances the lower tension and delivers stitches that meet in the middle of the fabric. Test and retest.
The key is to balance the resistance.
It’s good to be testing. Use some scrap material to sew a seam with a straight stitch and then a moderate zig zag stitch. Check the stitch and confirm the tensions are balanced. If you notice any problems continue experimenting till you get satisfied. It goes without saying that testing on scrap prior to sewing on your fine finish fabric saves you from a lot of frustration and you’ll sew more confidently.
There might be irregularities on one side of a zig zag stitch but not on the other. Test and adjust to your best capability. Some machines have design limitations that make a perfect zig zag stitch nearly impossible. For a perfect stitch you need to have a better machine.
Sew with confidence. Once you understand the adjustments of tensions on your sewing machine, you’ll be able to produce beautiful flawless pieces. If nothing seems to work, seek the help of an expert sewing machine technician.