How to draw the bottom line of an old sewing machine

The following figure is used to illustrate:

1. First, unscrew two screws that fix the needle board with iron sheets.

2. Press the lower left corner (or lower right corner) of the needle board, and the needle board will tilt upward, so you can take off the needle board.

3. Here, you can directly see the adjusting screw for the tightness of the bottom line. When leaving the factory, in order to prevent the screws from slipping due to vibration, there will be a paint seal.

4. Before adjustment, install the bottom line and pull it out to feel the tightness.

Pull the thread outward, feel the original tension, and remember the feeling of pulling the thread on your hand.

5. Find a small screwdriver to adjust the screw: clockwise rotation is tightening, counterclockwise rotation is loosening.

Pay attention to pulling the steel wire when screwing the screw, so that you can feel the tightness change of your hand.