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How can I properly adjust my tension?

First, learn how to distinguish tension issues from other machine problems before making any tension adjustments. Tension imbalance is the usual cause for the following problems:

  • Loops on the back and top
  • Thread pulling in corners when changing directions
  • "Pokies" on the quilt back (little loops of top thread that are pulled to the quilt back)
  • "Flat-lining" or "railroad tracks" on the quilt back (the bobbin thread looks like it is simply laying on the quilt back and is not forming proper stitches)

SPECIAL NOTE: Tension issues are rarely fixed by re-timing the machine. Re-timing is the solution when your machine is skipping stitches in the manual sewing mode, or when you have broken or jammed a needle and have affected the relationship between the needle and hook. Thread breakage can be caused by imbalanced tension, but breakage can also be caused by poor quality or damaged thread, as well as burrs on the hook assembly from needle breaks.

Before diving into the many factors that can affect your tension, let's first review the basic procedure to follow when your tension seems imbalanced:

  • Check the thread path. Is the machine threaded correctly?
  • Make sure the top thread is "snapped" firmly between the tension disks, not riding on top of them.
  • Clean out the bobbin case. Every bobbin change, remove lint that may have built up inside the case and under the check spring. Also check under the tension finger on the outside of the case. Thread fibers can build up under the finger, reducing the tension on the bobbin thread.
  • See if you can achieve proper tension by adjusting top tension first; if the desired look is not achieved, adjust the bobbin case tension. (Remember that you may need to adjust the top tension knob a half-turn or more before you'll see much impact on the thread tension; however, the bobbin case tension is much more sensitive and should be adjusted only about 1/8 of a turn at a time.) Sometimes you may need to turn the top tension knob several rotations tighter or looser. Use this phrase to help you remember which way to turn the tension knob: "Lefty-loosey, righty-tighty."
  • If the top thread "lies"on the quilt top, it's winning the thread tug of war and is pulling too hard. Start by loosening the top tension. If you have extensively loosened the top tension and see little or no impact, then tighten bobbin case tension. Be sure that some tension still exists on the top thread. You should feel resistance as you pull the thread through the needle's eye.
  • If the bobbin thread "lies" on the quilt back, start by tightening the top tension, which will cause the top thread to pull a little harder. Usually this will solve the problem. However, if your thread is fragile, increasing the top thread tension might cause your top thread to break more often. In this case, you'll also want to loosen bobbin case tension so that it's not putting as much stress on the top thread. If you've tightened the top thread extensively and are still not seeing results, then also loosen the bobbin tension so that the top thread can pull the bobbin thread into the quilt's layers.
  • Use the "bobbin drop" test (see below) as a starting point, but be willing to adjust bobbin tension beyond that, depending on your thread choice. Insert a bobbin into your bobbin case, ensuring that it spins clockwise when you pull on the thread tail. Now try to lift the bobbin case by the thread tail, and give the thread a gentle tug. (This is also called a "yo-yo test".) The following numbers are a simple guideline only, not an "absolute" setting for the bobbin case. The thread type, batting, tautness of the quilt and even fabric content can change the bobbin setting. Start here: look for 3-4 inches of "drop" for pre-wound bobbins, 4-5 inches for aluminum bobbins, and 5-7 inches for metal bobbins. It is OK if your bobbin is so loose that it zings to the floor if your tension looks good. Do not be too concerned about a "magic number" for bobbin drop. Adjust the top and bobbin tension until your stitches look nice, regardless of any preconceived notion you had about what the "proper" bobbin and top tension should be.
  • Consider keeping different bobbin cases for different threads to make thread changes easier. Cotton thread is weaker than polyester, for example, and will usually require looser tension in the bobbin case. Depending on the thread and its thickness, sometimes it will have little or no tension at all! Use a permanent marker or fingernail polish to mark the cases for different bobbin threads or even bobbin types, and adjust each one accordingly.
  • Try using a light-weight bobbin thread, such as Superior's Bottom Line, or another thread in the 50-60 weight range, when you are using thicker top threads. The thinner thread fights less with the top thread and produces more consistent tension.
  • Invisible nylon or polyester thread can be used in the bobbin to help with tension issues or difficult thread color decisions. Wind the thread on a metal or aluminum bobbin, but only wind it half full to prevent stretching (if you are using a "big bobbin" {Style M} only wind the bobbin about 1/4 full). (If your bobbin winder has a tension knob, also loosen the tension knob on the winder before winding invisible thread.) Loosen the bobbin case tension considerably. If you'd like to use the invisible thread in the needle, you'll also loosen the top tension by as much as a full turn or more.
  • Carefully examine the front and back of your quilt after testing your thread choice; some threads may appear to create bad tension, when in reality, you are just seeing the thread inside the needle's hole. Your eyes can fool you into thinking the tension is off when the thread is actually locked in the quilt's layers. You should actually be able to "feel" incorrect tension with your fingernail by running it along the top or bobbin thread path you have stitched. It will make a clicking sound as your fingernail catches on the thread bumps left by imbalanced tension. If you can "see" it, but can't "feel" it, your tension may be absolutely fine. Large needle holes typically will close up after the first washing, and can often be coaxed closed by running a fingernail over the hole.

Many factors contribute to maintaining consistent tension. The most obvious factor is thread choice. However, many other variables can also have an impact on thread tension, including:

Fabric content

For example, tightly woven fabrics such as batik can create uneven tension caused by the needle's scarf entering the fabric and pulling it up and down. Try slightly loosening the fabric between the rollers, and making sure your hopping foot is set to the correct height for thin batting.

The hopping foot should be adjusted so that when you lower the needle to its lowest position using the fly wheel (not your single stitch button), one business card should slip under the foot with just a slight resistance. Click here to learn how to adjust the hopping foot. On the other hand, if you use a high loft batting, the foot may need to be raised to accommodate the extra thickness. Just remember to reposition it when you return to normal quilting.

Unwashed fabric with sizing still in it can also impact stitch quality. With stiff, heavily starched fabric, the thread lays on top of the fabric instead of nestling between the fabric's fibers.

Fabric tautness

Fabric that is too tight between the rollers also doesn't allow the thread to nestle into the fabric and increases needle flex. Instead, try slightly loosening the fabric layers. When you move the quilting machine around on the fabric, your machine's throat should look like a "mole" crawling around under ground.

Batting content and thickness

Flat battings such as thin polyester and cotton don't provide a great deal of "air space" for the thread to lock between the layers, especially with longer stitch lengths. Try a fine weight thread, a batting with a bit more loft, or even increasing the number of stitches per inch. Dense batting can also make it difficult for your machine to lock the stitches in the layers. For best results, use a batting that has a little loft, such as a blended batting, wool, or more lofty cotton or polyester.

Direction the machine is moving

The machine's hook rotates in one direction only, even though the machine can be maneuvered in any direction. Therefore, in some instances the machine is actually stitching "backward", almost like holding the reverse button on a traditional sewing machine.

For example, if you stand on the free hand or needle side of the machine and quilt a straight line to your left, the tension will not be quite as perfect as if you moved to your right. That direction is like sewing "in reverse mode". It causes your needle to meet the hook a bit too soon, so the stitch formation changes slightly. When you move the machine right to left (when viewed from the needle side) or left to right (when viewed from the pantograph side) you may notice more "railroad tracks" as a tension problem. Since this phenomenon is caused by needle flex, you can improve the stitch quality by using the correct size needle, slowing down, loosening your fabric, increasing your stitches per inch, and tightening the top tension while also loosening the bobbin tension.

We recommend that you generally move from left to right on the free hand side of the machine, and from right to left on the pantograph side. (Yes, this means that even though your pantograph pattern may have two rows of the pattern printed on the paper, you should complete the first row, tie off, and return to the far right side of the table to complete the second row for the best all-around stitch quality.)

Needle flex

If your movements are jerky or you are moving faster than the stitch regulator or motor can keep up with, the needle may flex as it enters and leaves the fabric. Strive for smooth, consistent movement, and adjust the motor speed if you are in manual mode, so that the motor keeps pace with you.

Also, needles smaller than 4.0 will have more flex in their shafts, increasing the chance of imbalanced tension. Needle flex is the single most common cause for the tension problem called "flat lining" or "railroad tracks". Watch this video to learn more about needle flex and tension.

Machine speed and stitch length

With traditional sewing, different fabrics and techniques require different stitch lengths. The same holds true for quilting. In some instances, a long stitch length such as 7-9 stitches per inch will create pulling and puckering on the fabric, especially if thin batting is used. Try increasing the stitches per inch to 11-12. In manual mode, strive for consistent length as well.

Spool mount

Study the thread and determine how it is wound around the spool. "Cross wound" thread typically performs better mounted vertically (resting on the back spool holder). On the other hand, thread that wraps around a spool in a continuous circular pattern (called "stack wound") performs better when mounted horizontally. This allows the thread to feed off the spool without creating a corkscrew effect that can cause tension trouble and thread breakage. Click here to order a Hartley Spool Holder from us. The Spool Holder is a thread guide that allows the thread to spool off the cone instead of twisting.

Humidity

Natural threads such as cotton and some rayons can literally dry out in arid conditions, making them brittle and more susceptible to breaking. Some quilters "re-hydrate" threads that are misbehaving by storing them inside a plastic bag in the freezer overnight before using them. Others have success taming unruly threads by treating the spools with liquid silicone, available in the notions department of many sewing centers (Sewer's Aid is one well known brand.)

Thread content

Each thread has unique properties that will require tension adjustment. Even thread color can impact your tension and thread breakage! (For example, some dark colored threads such as black, navy, brown and even scarlet can tend to break more frequently. More dye is needed to achieve these colors, which weakens the fibers of some thread.) Thread quality also plays a stake in tension.

For example, some quilters successfully use serger thread in their long arm machines. However, this thread is not designed for heavy wear and the stress caused by traveling through fabric and batting. That's why three or four strands of the thread are used in sergers. Use high quality thread from a respected manufacturer for best results.

Different top and bobbin threads

Mixing thread varieties on the top and in the bobbin often will require tension adjustment. For example, a pre-wound bobbin usually contains polyester thread, which is very strong. If you tried cotton thread with a pre-wound polyester bobbin and made no tension adjustments, the bobbin will usually win the thread "tug of war" and either pull the cotton thread to the back or will break the cotton thread.

If you tried to tighten only the top cotton thread tension, it will most likely break. You'd have to also loosen the bobbin case tension to give the cotton thread a chance to pull the bobbin thread up into the quilt's layers.

If you have more questions about thread and tension, feel free to call us at 800.426.7233 or email us. We're here to help!

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