Top Tension Adjustment

Start by looking at the machine.

As you sit at the machine most of them have a tension regulator directly facing the user. A numbered dial that may go from 1-9 or 1-4 or, on older machines, it may simply be a knob that turns. On some older machines, the tension regulator is at the end of the machine.

All tension regulators work on the same principle. The upper thread passes between two spring-loaded discs. By turning the dial clockwise or anticlockwise you increase or decrease the pressure on the thread as it passes through. Do not be afraid to turn your tension dial. A skilled operator may alter the tension many times while sewing a garment that varies in thickness.

Go try turning your dial.

First though, note where it is before you start and make sure you put it back to that mark.

Now did that feel good? Once you get used to adjusting your tension you will be able to impress friends and influence people. Well, not quite, but you will have the satisfaction of being the most popular person in your quilting class!

One important note. There are many machines on the market today that say AUTOMATIC tension. Is there really such a thing? I doubt it. Is there a little Pixie sitting inside your machine waiting for your fabric? Does he peek out of a small hole in the top of your machine? “Ah top of the morning to you, that material is thin but I reckon densely, so I’ll put your tension just there!”

In reality, most of these machines use the same old dials with the numbers removed and AUTOMATIC written on them. I know, I sell them. There are a few complex computer machines that also boast automatic tension, but they still can have trouble. It is a great selling point but you do need to learn to adjust your tension. There are those few computer machines that really do have self-adjusting mechanisms, but we are not concerned with them.

As you turn the dial clockwise, you are increasing the tension. Anticlockwise, decreasing it. The lighter the pressure on the dial the lighter the upper tension is in the fabric. What we are looking for, in a perfect stitch, is one that is interlocked evenly in the middle of the fabric layer.

For an illustration, open your hands and face them toward each other with your fingers apart. Now slide them together, interlocking your fingers. If you look at the palms of your cupped, joined, hands you will see the formation of a perfect interlocked stitch. This is what we are trying to get on your sewing machine. If the stitch is unbalanced the top or bottom thread can be easily pulled out. This gives you a weak, stitch.

There are the usual classic faults in tension. Loose threads, looping, puckering, bunching and many more. What we want to do is eliminate them all by understanding the simple procedure of tension adjustment. I have listed on my linked Fault Finding Page all the other faults that affect your sewing machine and that are not covered by tension adjustment.

OK, so here goes. We know that a simple twist of the wrist can be the difference between a perfect stitch and one that drives you crazy.

Firstly we must make sure the tension unit is working. Whatever number your tension dial goes up to, place it at half that, so you are in the middle of the dial. If your dial is un-numbered, turn from lowest to highest tension and judge the halfway point, set the adjustment to that point.

Put a reel of thread on your machine and thread the monster. Finally, pull the thread through the needle’s eye with the foot raised.

The reason the foot must be raised is that most machines have an automatic tension-disc release connected to the presser foot. As you raise the foot the disc’s release, allowing you to pull the thread through without bending the needle too much or breaking the thread.

Check that this is working. Pull the thread through with the foot up, then lower the foot and see what happens when you pull the thread with the foot down. It should become tight to pull.

If the thread is not tight enough to bend the needle—

  • your tension dial is not working properly, or
  • the tension so low that it does not work, or
  • the thread is not in the tension unit properly
  • At this point we must stop and talk about threads.

Some old threads cause so much trouble that they are better thrown away. Some threads are lumpy, some perish and some threads are riddled with knots.

When adjusting your machine always use a good quality thread. I, myself, prefer polyester threads as they give a good quality stitch with a bit of giving. Not many people realize that the top thread passes through the eye of the needle many times before it finally gets taken up in the fabric. You can see this, for yourself, by marking the thread above the needle and watching it as you turn the machine by hand. Polyester threads bear up to this rubbing—through the eye of the needle—much better than cotton. But, whatever threads you use, make sure it is of good quality.

You can carry out a little test here. Pull an arm’s length of thread off the reel and hold it between your hands so that the thread drops in front of you in a wide U shape. Move your hand’s closer together and see what the thread does. If you have a balanced thread nothing will happen. If you have an unbalanced thread the thread, as it gets closer together, suddenly twists around itself. This causes lots of problems, twisting around thread guides and jamming into tension disks. Do not use unbalanced thread.

In normal sewing, never mix threads on a machine unless you want to visit the lunatic asylum.

If the tension disks appear to be too loose, even on the tightest (clockwise) setting, and the thread is not being gripped, first check that the thread is between the disks, then check that there is nothing jammed between the disks that stops them from squeezing the thread (gently pry them apart, with minimum tension and look). You may have to dig out any remnents of thread that has become wound around the middle stud.

If the tension disks appear to be too tight, on the loosest setting, the disks may be rusty or there may be a foreign object lodged between them. Remove any foreign material. You might be able to polish lightly rusted disks by using light string around the disk slot and pulling it back and forth. In severe cases consult your repair person.

Back to business. Now that we have made sure the tension unit is working we need to adjust it to get a lovely stitch in your work. What we must do at this point is find an average balance for the average material. So get some normal fabric, say a strip of clothing-weight cotton cloth. Fold it double as if you were going to sew a seam. Place it under the machine and start to sew. Now examine the stitch. Remember what we are looking for—a balanced, even, stitch on the top and bottom, with the lock right in the middle of both layers.

A quick test you can carry out at this point is to get the end of one of the threads that is coming from the stitched material and pull it sharply. If it snaps on the first couple of stitches then it means the stitch is securely on the fabric. However, if the thread can be pulled out you will need to adjust your machine tension.

One point to note is that you can have a secure stitch that is too tight and puckers the work. We will deal with that shortly.

IMPORTANT At this point I must bring to your attention a really important factor. The top tension controls the quality of the underneath stitch in your fabric. It is the top thread that is being taken, by your machine, around the lower thread and then pulled back up. Too little top tension will not bring the lower thread far enough, too much will pull the lower thread right through both the fabric layers.

If you are still with me then things are looking good, have your eyes started to glaze over yet? Be patient we are on our way. Think of it as searching for the Holy Grail of tension balancing. At the end of your journey you will be enlightened and your path through the maze of tension adjusting will be clear.

Back to business. What we need to do now is to alter the stitch according to what the problem is. The lower section of the page deals with lower tension adjustment. I must impress on you that you should carry out Upper Tension Adjustment first, as this is much easier and the most common cause of a poor stitch, 9 times out of 10 in fact.

If you have a perfect underneath stitch but a straight-line stitch on top and turning the tension dial has no effect, go to lower thread adjustment, further down the page.

Note Some of the large reels of thread available today can alter a well balanced machine and throw the stitch balance out because they are harder to turn when the tread is unwinding. If you are having tension trouble and are using a large reel of thread, wind the thread onto a bobbin and place the bobbin on top of the machine and use it like a small reel of thread. Now continue.

What is the problem with your stitch? Is it all loopy underneath? This is the most common problem.

If you have a big mess underneath then your top tension is not functioning or you have threaded the machine wrongly. See the fault finding link.

So, here we are at last, down to the nitty-gritty. It is so simple that it hurts. By adjusting the top tension clockwise the loops will slowly disappear. Run along about 6 inches of fabric and examine the underneath stitch. Alter the numbers one at a time, say from 4 to 5, check each time you do. Keep going until you find that the top and bottom match. Remember the hands? Now, the number that you have reached on your dial is the BALANCE POINT.

It does not matter what the number is. All machines, like humans, are slightly different. One machine may run beautifully on number 2 while another machine of the same type will be running on number 7.

A professional sewing machine engineer usually balances your tension dial to the middle so that you may increase or decrease it. This is an internal adjustment for trained experts.

Once you have found this BALANCE POINT make sure you remember it. From this number you should be able to sew 90% of all fabrics. You may decrease the number for lighter work, say nets or satin, and increase it for curtains or denim. But always put the tension back to this point.

If the top and bottom tensions are balanced but both too tight the fabric will pucker. Loosen both top and bottom tensions a little at a time (lower thread adjustments) until a smooth stitch is created.

To finish off the top tension adjustment, one final point. It will not matter how many times you adjust your tension dial; master the dial and the world will be yours.

Well done!