Sewing Machine Tensions Part 4

How do you adjust the bobbin tension?



How do you Sewing Adjust Bobbin Tension?


Tensions can be a common cause of problems. In extreme cases this may require the assistance of a professional sewing machine repair technician. It may be helpful to take a sewing machine repair course or maybe even several sewing machine repair courses to master tensions adjustments.



Understanding how tensions work is essential for every sewing machine user. Sewing Adjust Bobbin Tension affects every stitch.



Some users dread dealing with tensions all together and just pray the stitch will look OK. Adjusting tensions, however, is easier than you might think.


As we have seen, tension is the amount of drag or resistance on the thread as it moves through the sewing machine. The tension on top and on bottom should balance properly. Perfect tensions will produce threads joined in the middle of the fabric with no excess thread on top or the bottom of the fabric.



There are two critical adjustments required to achieve this perfect tensions. First, is the bobbin tension. Second, is the upper thread tension.


Lets take a look at the Bobbin Tension System.


Antique sewing machines often used shuttles mounted underneath the machine. While there are a variety of different designs, the essentials are the same. Today, Bobbin Tension may involve top loading bobbins, front loading bobbins, or even side loading bobbins.



Thread is wound on a bobbin The bobbin is placed into a case or holder. (For more information on bobbin tension with shuttles check out Antique Sewing Machine Repair). The thread in the bobbin is drawn through a tension device or spring and up to the top of the sewing platform.


Important for Sewing Adjust Bobbin Tension.

1. Be sure you have the right bobbin. This is vital for Sewing Adjust Bobbin Tension.

2. 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.

3. Be sure to place the bobbin in the bobbin carrier exactly the way your sewing machine manual says. Follow your instruction manual for Sewing Adjust Bobbin Tension. 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.

4. Thread through the lower tension. Usually, this means the bobbin thread will peal back through the bobbin tension rather than follow along or just flop in the wind. Notice the piece of metal on top right of the carrier. A small metal spring usually built into the bobbin carrier applies pressure or resistance to the bobbin thread. This is the bobbin tension spring. A tiny screw holds the tension spring in place. Turning this screw to the right will tighten the lower tension. Turning it to the left will loosen the bobbin tension. (“Righty Tighty, Lefty Loosey”).

5. Some bobbin carriers are built into the machine or fasten in place to receive the bobbin. Other bobbin carriers are made as bobbin cases which detach from the machine to receive the bobbin and then are reinserted after loading the bobbin.

Test the tension of removable bobbin carriers by doing the following.

Pull off about six inches of bobbin thread through the tension.

Dangle the bobbin carrier with the bobbin in it while holding the thread above it. The lower tension should hold the carrier so that it does not drop. If it does, just turn the screw a quarter turn to the right. If it does not drop, try bouncing the carrier a little. If the tension is properly set, the carrier will drop a little and stop. If it does drop a couple of inches and stops, all is good.

If the carrier does not drop at all even after pretty good bounce, the tension is too tight. Turn the screw a quarter turn to the left. Try again.

Many machines have a drop in bobbin that fits into a bobbin carrier below the needle plate. Once the bobbin is placed in the carrier, the thread is drawn under a tension spring. The same gentle pull test used in the front loading bobbin can be used with the drop in bobbin, but it is a bit less precise. If you continue to experience difficulties with the bobbin tension, it may be adjusted by turning the small tension screw on the spring of the bobbin carrier.

You may also seek the expert assistance of your local sewing machine repair technician if needed. You may also consider a number of sewing machine repair courses. A special spring loaded gauge may be used to measure the actual tension on the string, but in most cases it is not required.

Double check to identify any worn parts that might snag the thread. If you find a rough spot, burr, or other such spot, correct the problem before bringing the thread up through the needle plate hole and preparing to sew.

Sewing Machine Tensions Part 3

Sewing machine performance is often measured by the quality of stitches it produces. If the tension are messed up, the quality will be poor. In this case, it does not matter whether the sewing machine was a $99 special or a $12,000 Bernina. Perfect tension is a must.

If extreme cases, you may need to see your professional sewing machine repair technician. You may even want to take a sewing machine repair course or a series of sewing machine repair courses. The more you understand sewing machine tensions, the easier sewing will be.

Like two teams playing tug of war, rope is stretched across a stream (or line). Each team pulls on their end of the rope. One team pulls harder than the other. Them the other team pulls harder. Back and forth the teams pull against each other. Eventually, the reach a stalemate. The pull of each team is offset by the pull of the other team.

Like a playground teetertaughter, one person straddles the board on each end. First one pushes off and up they go. The other comes down, and pushes off. Up they go. Up and down. Down and up. Then the two kids work to position them self just right. They push off so gently and easily that the board comes to balance with the two kids both half way up.

Sewing machine tensions are just like these two examples. Tension is by definition the amount of pull, drag, or resistance the thread has as it flows through the sewing motion.

Along the top of the sewing machine, is the upper thread that passes through the tension discs, the tension spring, the take up lever, and eventually the eye of the needle.

On the bottom is the bobbin. It rides secluded inside its bobbin carrier, with its thread neatly flowing under the bobbin tension spring.

The top thread is drawn down into the sewing machine as the needle drops through the needle plate. However, the thread has resistance on it as it moves. The thread tightens as it moves down, and then looses as it moves back up. The sewing machine take up lever lists the thread to maintain drag even as the needle rises.

The thread from the bobbin is also under resistance. It is draw up by a overlapping loop with the upper thread. As the needle rises, the bobbin thread rises. However, the bobbin tension also pull back creating drag on the thread.

As we saw in our two illustrations, there is a tendancy for upper and lower threads to pull against the other. If the upper thread pulls harder than the lower thread, you will see puckers of excess thread collect across the top of the seam. If the lower thread pulls harder, you will see a nice looking top seam. But when you look under the fabric, you will see gobs of excess theads collected.

Perfect sewing machine tensions are achieved when the upper and lower thread drag is equalized. The thread knot forms in the center of the fabric. You see no excess on top of the seam or under the fabric.

In our next post, we will explore how to insure perfect tensions every time. If you would like a free sewing machine repair course, check out our 7 Steps To Peak Performance For Your Sewing Machine at http://www.fixsewingmachines.com.