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Are You Suffering From the Tension Blues?

I get a lot of calls from folks having tension problems with their machines.  Here are a few tips, hints, and facts about sewing machine tension.

1.   There are tension adjustments for the upper and lower threads.

2.   Most of your adjustments will be made using the upper tension knob/adjuster.

3.   In theory, the tension on the upper thread should be the same as the lower thread, though this is rarely the case.

4.   What you want is the top and bottom stitch to lie tight (see diagram below) looking the same.

5.  When you have looping or loose stitches on the bottom, then you should slightly tighten the upper tension in steps until the upper and lowers stitches look the same..  If your upper tension is as tight as it goes then you need decrease the bottom tension  (I'll explain how below) or your tensioner may need recalibration (by a professional).

6    When you have a top thread that lays across the fabric and a good tight stitch on the bottom,
then  you should loosen the top tension (always a little at a time).  If your upper tension is as  loose as it goes (very rare) then you need to increase your bottom tension.


Adjusting Bottom Tension

Most of the time this is not necessary.  But when all else fails you can try this before you call me or any other Technician.

The bobbin case, whether it is a pull out case or a case that you drop your bobbin into, they all have a tension adjusting screw.  If you are going to attempt to adjust the bobbin case tension then do so 1/8 of a turn at a time (some folks are bad with fractions so 1/8 is just 1/2 of 1/ you're completely confused!!)

       These are eighths.

You'll need a really small screwdriver, such as an eyeglass flat blade screwdriver.  Remember 1/8 of a turn then test.  If you turn it too much or get lost in "tension world" you will be miserable.

Picture of a Class 15 Bobbin Case and Adjustment Screw (Below)

Class 15 Bobbin cases are removed from the machine to take out or replace the bobbin.  They are very easy to adjust. REMEMBER...1/8 OF A TURN CLOCKWISE TO TIGHTEN AND 1/8 OF A TURN COUNTER-CLOCKWISE TO LOOSEN TENSION.

Picture of a Class 66 Bobbin Case and Adjustment Screw, along with two typical Class 66 bobbins (Below)

Class 66 bobbin cases are installed into the machine from top down and are held in place and in adjustment by various means. Do not attempt to remove this bobbin case...leave it to a trained technician.  This type of bobbin case comes in metal or a black synthetic with some metal parts. Usually if you slide your bobbin plate open or flip it may be the case, you will see at least one and maybe two small screws the tension adjustment screw is usually on the left (as in this case).  Some are in a little tunnel, for these you have to look carefully or find the head with that little screw driver.   REMEMBER...1/8 OF A TURN CLOCKWISE TO TIGHTEN AND 1/8 OF A TURN COUNTER-CLOCKWISE TO LOOSEN TENSION.
Other types of bobbin cases have tension adjustment screws as well.  If you want to try to adjust the lower tension, send me a close up picture of your bobbin case and I will return the picture with annotations showing the tension screw.  Send to

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