Yes, and it is why a machine that sews beautifully on a flat seam misbehaves at a thick junction.
More layers need more thread per stitch, because the needle travels through a greater depth of fabric and the lock has to sit somewhere inside it. The same dial setting therefore holds the top thread back harder than the stitch needs, and the stitch reads as tight.
The presser foot is the other half of the problem. Climbing onto a thick section tips the foot, and a tipped foot stops holding the fabric evenly. The feed falters, the needle deflects, and the resulting mess gets blamed on tension when the cause is mechanical.
What to do at a thick junction. Level the foot with a folded scrap or a hump jumper. Lengthen the stitch. Slow right down, and turn the handwheel by hand over the worst of it. None of that involves the dial.
When to change the dial after all. If a whole seam runs on many layers rather than crossing a step, test on that number of layers and set the tension for it. Bag making and heavy hems are the usual cases.
Test on what you will sew. A tension proved on two layers of scrap tells you nothing about six layers of the same fabric.
And check the needle is heavy enough. A needle deflecting through thick layers gives skipped stitches that look like a tension fault and are not.
Questions people actually ask
Why does it only go wrong at the seam crossings?
Because that is where the layer count jumps and the foot tips. Support the foot and slow down; the setting is probably fine.
Should I loosen or tighten for many layers?
Usually loosen slightly, after testing. But fix the foot and the stitch length first, because they account for most of it.
Last reviewed 2026-08-11