Here are some tips on how to adjust the tension on your Smartstitch commercial sewing machine:
1. Understand the tension system: Commercial sewing machines usually have a tension assembly, which consists of a tension disc, a tension regulator and a tension spring. The tension disc fixes the upper thread, and the tension regulator adjusts the tension by controlling the tension of the upper thread.
2. We use the "I" test to test for tension. Basically it's a one inch post of satin stitch. Now we turn it back and compare the bobbin to upper thread ratio. Ideally, you can see a third of the top line run along the sides, and then a third of the bottom thread run down the center.
3. Thread the machine: first thread the machine correctly. Make sure the upper thread passes through all necessary guides, tension discs and needles.