Insert the bobbin in the case so the thread unwinds in the opposite direction that it feeds out of the case. Draw the thread up under the tension plate and out the opening (4). For thick threads that can't go under the tension plate, simply feed them out the opening, bypassing the tension plate. To adjust the bobbin tension, remove the bobbin case(where the bobbin is placed) and locate the small screw .
Adjust the lower tension by turning the tension screw, which holds the tension plate in place. Turn the screw counterclockwise to loosen and clockwise to tighten. Move the screw only a quarter turn or less at a time. Test the tension by pulling on the thread-it should have a little resistance. Note: Different types of race mechanisms require slightly more or less tension. Test each adjustment-a little turn of the screw can have a big effect on the tension. Note. Embroidery and computerized machine thread tension must be adjusted on the screen.
Once the bobbin tension is set, it rarely needs adjusting. Slight adjustments for different fabrics are made using the upper tension. Some people have a bobbin case for regular sewing and a second, adjusted one for special techniques.
kim, July 2005