Tensions are a common source of problems in sewing. Understanding how tensions work is essential for every sewing machine user. It is not as complicated as some believe, and not as simple as some might think.

When you sew, thread from the top of your machine and thread from the bobbin lock together to form a stitch. As the thread moves through the sewing machine, drag is created which we call tension. When the drag from the top correctly balances the bobbin drag, the lockstitch will form in the middle of the fabric without extra thread on top or bottom of the fabric.

Thread from the spool on top of the machine is threaded through some guides, the tension discs, the take up lever, and needle. To increase the tension, just turn the tension knob to the right. To loosen, turn left.

Under the arm of your sewing machine is a bobbin carrier where you put your bobbin. You might not have thought much about the tension system here, but it is very important. Antique machines used an elongated shuttle, but basically served the same purpose. Today machines have carriers loaded from the front, top, or left side.

Basically, all the bobbin tension systems work alike. The bobbin goes into the bobbin carrier or holder. Thread wound on the bobbin, is pulled under a tension spring. Eventually, the thread is drawn up through the hole in the needle plate.

Here are some important things to keep in mind when your get ready to sew. First, be sure you have the right bobbin.

Second, be sure the bobbin thread is properly wound with no loops or loose threads and not too tight either. The thread should be smoothly wound around the bobbin.

Third, be sure to place the bobbin in the bobbin carrier exactly the way your sewing machine manual says. The bobbin thread usually moves from left to right or clockwise around the bobbin as it turns. However, there are models that are exactly the reverse. The key is to observe how the thread enters the bobbin carrier tension assembly. The thread should trail back under the tension so that it does not slip out during use.

Thread the bobbin tension which looks like a small piece of metal on the outside of the carrier. Your sewing machine manual or sewing machine technician can should you if you need help. Draw the thread back under the spring.

You can adjust the amount of pressure applied to the thread by turning the small screw located on the tension spring. To tighten turn it clockwise. To loosen turn it counterclockwise.

There are many different types of bobbin carriers, find out how yours is suppose to work and always use it the same way. Some machines have carriers that are already installed on the machine, and all you have to do is put your bobbin into it. Other machines have detachable carriers that you put your bobbin into. Then put the carrier into its socket.

Tension is easy to test on detachable carriers. After inserting the bobbin and drawing the thread under the spring, hold the string and allow the carrier to dangle. If it drops, tighten the tension. Bounce the carrier a bit. If the tension refuses to move, loosen the tension a bit. If it drops an inch or so, it is about right. Now hold the carrier and pull the thread with your other hand. Does it come off smoothly, you are all set.

Drop in bobbins can be tested using the gentle draw test we used with the detachable carriers. Remember, the thread should flow smoothly through the bobbin tension with a gently pull. If it is too hard, loosen the adjusting screw. If you do not feel drag, make sure there is not lint under the tension spring and tighten.

Inspect the bobbin area for problems. Clean out the lint and dirt. Smooth any rough spots, burrs, or jagged edges. Be proactive by keeping your sewing machine in good condition. Once the bobbin tension is set, remember to check it whenever you change the size or type of thread you use.