How to adjust tensions on a sewing machine.

“The tensions are terrible.  Every time I sew, the threads bunch up.”

This and similar complaints are among the most common complaints by sewing machine users.  Excess threads bunch up under the fabric or bubble up on top of the fabric.  The stitch may be fine for an inch or two, and then suddenly they screw up and the whole job is ruined.

So how do you adjust tensions on a sewing machine?

There are several causes of improper tension.    One of the common causes of improper tension comes from inappropriate threading.  This may be of the upper thread or bobbin assembly.   Errors include missing a thread guide.  Threads may float on top of the upper tension discs.  Threads may miss the bobbin tension.  Each of these errors can cause havoc with the stitch quality.   Other causes include Rough spots, worn surfaces, lint and debris, burrs on the hook, bad needles, and bad thread. 

So how do you adjust tensions on a sewing machine?

Perfect stitches form when the upper and lower threads connect in a locked stitch in the middle of the fabric.    There should be no excess thread on the top of the fabric or underneath.  The thread should flow smoothly and tightly from one stitch to another.  There should be no  puckers, looseness, or wobbles.

So how do you adjust tensions on a sewing machine?

To achieve these perfect stitches the upper and lower threading must be appropriate.  The drag or resistance of the upper tension system and the bobbin tension system must balance each other precisely.

So how do you adjust tensions on a sewing machine?

Consider the  fabric like a stream of water.  The threads are like ropes across the stream.  One tug of war team pulls up and another pulls down.   Each team pulls across the stream.   

The lower team or bobbin team may pull harder than the upper tension team.  You can tell by the  excess thread under the fabric.  This is hidden until you lift the fabric to see ugly bunches of thread.  The stitch may even look fine on top while the threads jam up underneath.  

The upper team may pull harder than the lower team. Excess threads will pop up on top of the fabric.  Usually, you will see these balls, bunches, or bubbles of thread almost as soon as they stitch.  

So how do you adjust tensions on a sewing machine?

To perfectly adjust the tension,  double check the threading.  Check the bobbin and the upper thread making sure the thread  flows through upper and lower tensions properly.  Look for any snags or interruptions.  Adjust the lower tension.  Thread should flow smoothly through the bobbin tension with a slight tug and without snagging.   Finally, tighten the upper tension until it balances the lower tension.  This should produce stitches that meet in the middle of the fabric.

Oh, so that is how to you adjust tensions on a sewing machine.

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.  Check the zig zag or other stitch as well. It may not produce your perfect stitch.   Always test before sewing your finished seam.

You may notice irregularities on one side of a zig zag stitch and not on the other.   Test and adjust until it looks the best you can make it.  Some machines have design issues that make a perfect zig zag stitch almost impossible.  If you want a perfect stitch and you have one of these older machine, consider getting a better machine.

Oh, so that is how to you adjust tensions on a sewing machine.