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What About the Tension?

Posted: 10 October 2011 at 7:05 a.m.

Are you sometimes afraid to adjust the tension system on your machine? Mother Superior gives you permission to adjust your Thread Tension Dial once you understand a few basic principles:

Sewing machines are factory preset to have the top and bottom thread form even stitches when sewing with a 50 or 60 wt. thread. If the top and bottom threads are identical in fiber and weight, adjustments may not be necessary.

However, if we use cotton on top and poly underneath, or metallic on top and poly underneath, or a heavy thread on top and a fine thread underneath, it is necessary to adjust the tension settings. It is perfectly OK to use different thread types and weights on the top and bottom. Relying on a machine's automatic tension system is not enough.

Think of the top and bottom thread as having a tug of war. If the threads are identical and you are sewing on a single layer of fabric, both sides have equal strength and the result will be a draw. The sewing should therefore produce perfectly even stitches with no top thread showing underneath and no bobbin thread showing on top.

However, in the real world, the teams are rarely equal. One team will be stronger or bigger or faster than the other. We sometimes use decorative or sensitive threads on top. We often use different fibers for the top and bottom threads. We also add stabilizer or batting. Sometimes we might use a cotton bobbin thread and other times we use a polyester bobbin thread.

All these factors make it necessary to adjust the tension for each project. By adjusting the top tension either up or down, we are able to add or take away strength on the top thread team to equalize the tug of war battle. Following is a list of things that affect stitch results:

  1.  Batting. This adds drag on top thread. Cotton batting tends to grab the thread more than poly batting, adding more friction on the thread.
  2.  Fabric type. Dense fabric puts more stress on the thread.
  3.  Top thread thickness and type. Metallic is less flexible than cotton or poly. Poly is usually stronger than cotton or rayon.
  4. Bobbin thread type. Cotton bobbin thread tends to grab more than a smooth filament polyester. Sometimes grabbing is preferred and sometimes it causes problems. A smooth filament poly thread (not spun poly) in the bobbin will work better with metallic and other sensitive threads because its smooth finish acts almost like a lubricant, sliding nicely with the thread.
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  • 8. Todd P (03 January 2012 at 10:02 p.m.)

    Sandi, It sounds like the top tension is too tight. Also, if the needle is too small, the thread won't pass through easily which makes it harder to bring thread up from the bottom. Please take a look at our Thread Reference Guide for Longarm Machines and see the recommended needle size for each type of thread. Please call or email us at if you have any further questions or problems. Click on the Reference Guides button on our home page and it will take you to our Reference Guides.
  • 7. Sandi (30 December 2011 at 3:27 p.m.)

    Can't seem to get the King Tut to work on my HQ16 mid arm. I have both gauges and i am using the same thread for top and bobbin. the top thread just wont pull the bottom thread up right. I have cleaned everything ,changed needles ,rethreaded, changed to another bobbin. What am I missing?
  • 6. toni (07 December 2011 at 4:55 p.m.)

    I am using the rainbow series of Superior thread. They are new to me and beautiful but frustration is at its peak because of the breaking. I will try and looses the top tension and see what happens. Thanks for the quick answer. I will let you know.
  • 5. toni mcclure (07 December 2011 at 4:51 p.m.)

    why am I having so much trouble with my Superior Rainbow thread breaking on my quilting maching frame. I am using a 1500S Brother maching and it breaks every five minutes or more. Thanks.
  • 4. Superior Threads (21 November 2011 at 1:37 p.m.)

    You could have your tension too tight, so the thread can't get into the tension discs. (Or it could be you need to use Superior Threads)
  • 3. Karen P (20 November 2011 at 1:42 p.m.)

    What's happening with my thread when it jumps out of its threading track? Then the wheel won't turn. I'm using (or trying to use) Aurafil thread. Is that a tension issue or something else? Thanks!
  • 2. Raws (11 October 2011 at 10:14 a.m.)

    Thanks for helping solve the mystry of thread tension.
  • 1. Todd P. (10 October 2011 at 2:40 p.m.)

    Thanks for posting!

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