Issue link: https://docs.hic.us/i/403552
Thread Color – It's not really the color, but rather the dye. Different dyes affect the surface texture of the thread, which in turn affects how smoothly it flows through the machine. Thread Weight – When using anything other than a 40 weight thread, tension will be affected differently. Machine Speed – Different speeds affect the thread tension, such that it may not be consistent throughout the full range of machine speed. Needle Size – Smaller eyes cause more friction, which affects the tension. Dirt – A buildup of dust, lint and dirt along the thread path will affect the thread tension as it travels through the machine. Setting Bobbin Tension To achieve proper bobbin tension, place the bobbin in the bobbin case but do not put the thread into the "pigtail". Hold the end of the bobbin thread between two fingers and with a slight jerk of the wrist, let the bobbin case drop. It should descend about three to four inches. If not, then the tension is too tight. Adjust the large screw on the tension finger slightly and test again. If the bobbin case drops more than three to four inches, then the tension is too loose. Once again, slightly adjust the tensioning screw and retest. Just like with the upper thread tension, the bobbin "drop test" is an excellent means for setting the ideal tension. But in the real world, there will be situations where the tension has to be adjusted differently in order to achieve the desired stitch quality. www.hsi.us care@hsi.us 191