Thread tension is the balance between your top thread and bobbin thread. When it's right, the top thread wraps slightly to the back and the bobbin thread never shows on the front. When it's off, you get loops, breaks, or the dreaded bobbin thread peeking through.
The Tension Test
Stitch a column of satin stitches on a scrap, then look at the back. You should see roughly one-third bobbin thread in the centre and two-thirds top thread on the sides — the classic '1/3 to 2/3' rule. If you see top thread on the back, the top is too loose; if bobbin shows on the front, the top is too tight.
Common Tension Problems and Fixes
| Problem | Likely Cause | Fix |
|---|---|---|
| Bobbin shows on top | Top tension too tight | Loosen top tension |
| Loops on the back | Top tension too loose | Tighten top / re-thread |
| Frequent breaks | Tension too high or burr | Lower tension, check path |
| Puckering | Tension too high overall | Reduce tension, add stabilizer |
Before You Adjust Tension
- •Re-thread both top and bobbin completely — most 'tension' issues are threading issues.
- •Insert a fresh needle.
- •Make sure the bobbin is wound evenly and seated correctly.
- •Use quality thread; cheap thread causes inconsistent tension.
Adjust the Top First
Leave bobbin tension alone unless you're confident. Most tension corrections are made with the top tension dial.
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