Fixing Loose Thread Tension on a Sewing Machine
How to diagnose and fix loose or uneven thread tension, the cause of poor stitch quality on industrial machines.
Loose thread tension shows up as looping on the underside or topside of the seam. It is almost always fixable without a technician.
1. Re-thread the machine
Most tension problems come from incorrect threading. Re-thread the needle and bobbin carefully, following the machine’s thread path.
2. Clean the tension discs
Lint trapped between the tension discs causes uneven tension. Clean them with a brush or a folded piece of cloth.
3. Check the bobbin case
A damaged or worn bobbin case is a frequent cause of loose bottom tension. Replace it if the case is scored or the tension spring is weak.
4. Match the needle
A needle that is too small or bent also affects tension. Fit the correct needle size for the fabric.