Serger 101: Tension, oh the tensions!

by Heather on February 8, 2010

Four threads. So much fun! Yes, it really is.

Tension from tensions is common at the beginning, but its all in the perception.  Its really not that hard, its not brain surgery or even rocket science. I call it Ying and Yang. One cannot exist without the other and they must balance each other out to work properly.

I always start with the loopers. Remember that the loopers never pierce the fabric, they are held down by the needle threads.  Green is the upper looper and blue is the lower looper and the needles look like stitches from the “top” and pin pricks from the “bottom”.

Do you see much green here?  Sometimes its not this drastic.  There is definitely no loops meeting on the edge, like they should.  In this case the lower looper (blue) is coming over too much to the top.  On your tension dials, there are usually numbers.  The high the number, the more “pull” there is on the thread.  This is not a proper explanation, but this is how I remember it.  So the blue thread is too weak and the green thread is taking advantage and pulling it over.  On the loopers, unless there is something really wrong, I never move just one of them.  In this case, I would move the upper looper (green) to a lower number so that it doesn’t pull too much and the lower looper blue to a higher number so that can stop being such a push over (or pull over, as the case may be).  No one likes loopers that are push overs.

In this one, the lower looper (blue) is being the bully and completely taking control of the poor upper looper (green).  It probably stole its lunch money.  But the upper looper (green) needs to stand up for itself.  The exact opposite thing would happen here.  I give the upper looper a higher number on the dial and the lower looper a lower number.  When its all good, the loops should meet at the edges, nicely, with no bickering or fighting.

Whew.  Its like being a parent.  Onto the needles.  They are harder to photograph.

If your needle is too tight…..well….you know what happens to high strung people, they snap.  And the same for a tight needle thread.  Give this one a lower number and some Prozac.  Things will be much smoother.  If things get really bad, you might witness a needle breaking.  Intervene as soon as possible.

This one should be OBVIOUS.  Right?  Feel like you can pass the class yet?

Just kidding.  The red needle is loose, but its hard to see.  If I were to run my fingernail over the needle, it would move quite a bit.  Or if the left need was loose, pulling at the seam may show a lot of extra thread.  Its not obvious, but it can happen.

ahhh, here we are.  Ying and yang all good.

Please notice that the loopers hang off the edge just a tad bit.  I know that sewists like things nice and secure, but try to relax.  The loopers do not actually pierce the fabric.  If you have forgotten this, please re-read the post.  A little breathing room is good for everything.  Like trying to fit into your tight jeans when you have gained a couple of pounds.  You will look better and feel more comfortable if you don’t have to lay down on the bed to get them zipped up.  Don’t force your seams into a space that is too tight.  The seam will look better if it has breathing room.


1 Vicky August 26, 2011 at 10:43 am

Thank you for a explaining the tensions so clearly to me. The instruction manual that came with my overlocker/serger doesn’t explain it as well as you do. Love your sense of humour too.

2 Heather August 28, 2011 at 9:21 am

Thank you! I know that the instruction manuals that come with the machines are too technical and confusing for most people, me included! I’m so glad you found this useful.

3 elizabeth August 27, 2011 at 11:06 pm

Thank you, I think you are some clever cookie!!! + you explain things real cool!!!!

4 Heather August 28, 2011 at 9:21 am

Thank you!

5 G September 10, 2011 at 11:41 pm

Thank you, very helpful in conjunction with my manual.

6 Ginger Ratzlaff November 5, 2011 at 1:06 pm

My tension problem is a bit different. The back side looks like I am making a loopy fringe, the left needle stitches are so loose through the fabric that seams will pull apart leaving a 1/8th or more of thread showing. I am so confused. Can you help…or is it time to pay for a technician? I have a Babylock 5360D (old I know.)

7 cheese March 16, 2012 at 1:00 am

So the loops are MEANT to stick out that much from the edge of the fabric? I’m guessing there is no way of changing this?

8 Heather March 16, 2012 at 8:25 am

On a thicker fabric they don’t stick out as much. But yes, this is the way it should look on quilting weight cotton. You can tighten up the tension on the loopers but that will put stress on the needle threads which leads to other issues (seams not laying flat, items needing pressing after washing, threads visible at the seam line). Remember that the looper threads never go through the fabric, they are not holding the seam together.

9 Carole April 24, 2012 at 10:47 am

Thank you so much for your clever and humorous explanation of how to get a good tension. I am very impressed by your website. Love it! Now if I can just get a chain started…

10 Carole April 25, 2012 at 1:27 pm

Hallelujah! I have a chain on my dinosaur Babylock BL4-736. Solution was to a) make sure the DCx1F needles were installed correctly and b) thread with the loopers in the highest position possible. c) THIS IS NO WHERE IN A MANUAL: make sure the thread from the last stay to the upper looper is BEHIND the lower looper.

11 Christine August 4, 2012 at 10:05 pm

THANK YOU!! This post really helped me actually understand each thread’s purpose on the serger, and I was able to fix my problem!

12 z April 8, 2013 at 12:45 am

I know you posted this years ago now, but I was searching for something to explain why my seams were showing thread when I turns them inside-out. Now I know – just need to figure out which needle is loose so I can have tight seams! Love your Serger 101 series! I love my serger, but the only stuff I know about using it have come from trial and error! It’s so nice to have the basics explained!

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