By Kay Hickman
Learn how to properly adjust and troubleshoot tension problems to create perfect stitchouts.
What is Tension?
Tension refers to the balance between the needle thread and the bobbin thread. For standard stitching, the tension should be balanced. When stitching a perfectly balanced seam, only the needle thread is visible on the fabric right side and only the bobbin thread is visible on the wrong side.
When embroidering designs, a perfect stitch is actually unbalanced.
On the design right side, only the needle thread is visible. But when you look at the wrong side, the bobbin thread and also some of the needle thread along each embroidery-object perimeter is visible. In other words, hints of color should show on the design’s wrong side. If you only see the bobbin thread color, the tension isn’t set correctly for embroidery. The needle thread must pull slightly to the wrong side so only the needle thread is visible on the right side (A).
Tighter tension is needed in the bobbin to pull the needle thread to the design’s wrong side. Most embroidery machines accomplish this by having a different bobbin case that is pre-adjusted for tighter tension. In addition, you may also need to thread the bobbin thread through a pigtail, or a hole, in the finger of the bobbin. Some machines are threaded a bit differently in the bobbin area to create tighter tension. Refer to the machine manual for specific bobbin threading instructions.
To achieve ideal embroidery tension, use the correct bobbin thread. Quality bobbin thread is smooth and free of slubs. For best results, choose thread specifically labeled as bobbin thread. Bobbin thread is typically polyester, varies from 60- to 100-wt., and is more lightweight than embroidery thread, which is typically 40-wt.
Embroidery machines are balanced for a combination of heavier embroidery thread in the needle and smooth, lightweight thread in the bobbin. Using any other combination could result in tension problems.
Let’s troubleshoot tension problems, such as looping of needle thread or bobbin thread pulling to the fabric’s right side. Follow these four steps before making any adjustments.
- Replace the embroidery needle. A dull needle creates loops or tight stitches that mimic tension problems.
- Rethread the machine. Often, the thread isn’t properly lying in the tension disks, which can cause loose stitching. The thread may also be catching somewhere in its path, which adds tension to the thread.
- Clean the machine. Lint caught in a bobbin case throws off the bobbin tension, and thread caught between the tension disks affects the needle tension.
- Oil the machine. If the hook area of the machine becomes too dry, irregular bobbin tension may result.
If after following these steps you still have tension problems, adjust the needle thread tension on the machine.
Needle Tension Adjustments
It’s always easier to adjust the needle tension first before attempting to adjust the bobbin tension.
- Tighten the needle tension when the thread tension is too loose, which is usually characterized by looped stitching. In some cases, the design may have an overall puffiness without distinct loops. If the embroidery thread isn’t lying smoothly on the fabric’s right side, the upper needle tension may be too loose (B).
- Increase the tension to a higher number in 1/4 to 1/2 increments until you’re satisfied with the results. Test-stitch the design on scrap project fabric to ensure the tension is satisfactory. When test-stitching designs, use the same fabric and stabilizer type as used for the project because the fabric thickness can also affect the tension.
- Loosen the needle tension when the thread tension is too tight. If you see bobbin thread pulling to the fabric’s right side, the upper thread tension may be too tight. Tight needle tension is often identified on designs when stitches are very short or satin stitches are very narrow. Tight needle tension often occurs when you reduce the design size.
- Loosen the needle tension to a lower number in 1/4 to 1/2 increments until you’re satisfied with the results.
Bobbin Tension Adjustments
Most tension adjustment problems are solved by adjusting the needle tension. However, an occasional adjustment may need to be made to the bobbin tension. Some machine companies recommend that bobbin tension only be adjusted by a professional. Having your machine tuned up on a regular basis can prevent bobbin tension problems from occurring.
- If the bobbin tension can be adjusted on your machine, check the user’s manual for specific instructions. Be very careful when adjusting bobbin tension because the tension is typically set with a small screw that’s very easy to lose. Adjusting the bobbin tension should be your last resort after changing the needle, cleaning the machine, and adjusting the needle tension. If desired, consult with your sewing machine dealer for helpful advice when adjusting bobbin tension.
- The bobbin tension needs tightening if the bobbin thread is visible on the fabric’s right side. The bobbin tension needs to be loosened if the bobbin thread appears tight and pulls the needle thread too much to the wrong side.
Tip: To avoid adjusting tension for small lettering, use matching bobbin thread.
Troubleshoot Tension in Special Cases
For most projects, keep the needle tension set on the same number. However, there are a few special cases when adjusting the needle tension is advised.
Heavyweight or specialty threads: If the thread is heavier than the average 40-wt. Embroidery thread, you may need to reduce the needle thread tension because the thread is bulkier and won’t slide through the tension disks as easily. Reducing the thread tension slightly helps prevent thread breakage and keeps the bobbin thread from pulling to the design right side (C).
Very small lettering: When a design has very small lettering, the tiny satin stitches can create tension that is too tight. You may see white dots of bobbin thread showing around small lettering (D). Reduce the needle tension for very small lettering to achieve a smoother finish.
Very long stitches: Some embroidery designs are created with very long satin stitches to mimic a hand-stitched look. These long stitches sometimes become loopy and the needle tension may need to be tightened slightly for these designs. Don’t tighten the tension too much, as it flattens the embroidery and destroys the handmade look.
Speed: Slow down the machine speed, as very fast embroidery stitching can cause the needle thread tension to be too tight.
Certain stitch types: Sometimes triple stitch designs, such as redwork designs or design outlines, stitch too tightly. If this occurs, loosen the needle tension slightly for the outline portion of the design. However, slowing the machine speed is just as effective as adjusting the needle tension in these cases (E).
There are many wonderful designs available that quilt fabric layers together or even stitch together an entire project in the hoop. For these designs, use the same thread in the bobbin and needle that’s used for the sewing bobbin case. The stitches look more like ones created by a standard sewing machine instead of by an embroidery machine for a balanced look (F).
We hope these ideas help you troubleshoot tension issues on your embroidery projects!
Anchor: OESD, Nautical Bluework (collection #12058); Leaf: OESD, Fall Garden Party (collection #12358); Pear: OESD, Cutwork and Crewel 2 (Licensed Design Collection #47712); Quilting design: Quilting Fancy by Diane Gaudynski (Licensed Design Collection #47980).
This article originally appeared in Creative Machine Embroidery. Don’t miss any great stuff like this — subscribe now!