Common problems with sewing machines

1. Irregular movement of clothing materials

During the process of using a sewing machine to sew fabric, there may be irregular phenomena such as uneven movement speed of the fabric and long and short stitch duration. The movement of the clothing material relies entirely on the cooperation of the feeding teeth and pressure feet for forward transportation. Therefore, when the irregular movement of the clothing material occurs, it can be concluded that the teeth and pressure feet have malfunctioned or the pressure adjustment is improper. For example, the pressure on the presser foot is too low. If the fabric is not pressed tightly, it will cause irregular movement. At this point, simply turn the pressure regulating screw downwards to tighten the fabric. The presser foot is too high to hold down the fabric, which can cause the fabric to move around or not move at all. When adjusting, first lift the presser foot wrench, loosen the guide screw, and then move the presser foot rod from top to bottom to adjust the distance between the presser foot and the needle plate to a height of 7-8 millimeters. Then, tighten the screw and drive it to use.

Another reason is that the tooth screws are loose, causing the teeth to sway left and right during operation, preventing the fabric from moving forward in a regular manner. The handling method is to remove the needle plate. Tighten the two tooth screws. After tightening, install the needle plate and check both sides of the teeth for any friction with the edge of the needle plate groove. If there is friction, it can cause noise and machine weight. At this time, only remove the needle plate, loosen the tooth screws, adjust the tooth position to the middle of the needle plate groove, tighten the tooth screws, and then install the needle plate.

2. The fabric does not move forward

The movement of clothing materials is entirely transmitted by teeth. When the material doesn't move at all, the only way to find a problem is on the teeth. If the teeth are too low, the fabric cannot move forward. When adjusting, first pull up the machine head, loosen the screw of the tooth lifting crank, and then gently lift the tooth holder with a screwdriver to make the feeding tooth oriented. Expose the needle plate by 0.8-1 mm. It is the standard size for the height of teeth, as long as it is adjusted to this position, the fabric can move normally. Finally, tighten the screws. When tightening the screws, the machine head should also be pulled up.

3. Cloth material walking back and forth

When sewing fabric, there is often a phenomenon of the fabric moving back and forth, meaning one step forward and then one step back. This is caused by the high feeding teeth, which expose the needle plate too high on the surface. The teeth always move back and forth outside the needle plate, causing the fabric to move back and forth. When adjusting, loosen the screw of the tooth lifting crank, gently press down the teeth with a screwdriver to lower the feeding tooth to the standard height, that is, the teeth are exposed to a size of 0.8-1 mm from the needle plate, and then tighten the crank screw.

4. Cloth material backward

In sewing work, sometimes the fabric does not move forward, but instead moves in the direction of the operator, that is, the fabric moves backwards. This fault is caused by the incorrect angle between the upper shaft crank and the cam eccentric screw. The teeth are able to move forward in a rhythmic manner solely through the movement of the feeding cam. Because the cam itself is eccentric. So the tooth fork is moved back and forth, and the tooth fork in turn drives the feeding shaft and tooth rack, causing the teeth to move back and forth. It can be seen that the eccentric position of the cam is very important.

The standard angle between the upper shaft crank and the cam screw. As long as the angle between the cam screw and the upper shaft crank is adjusted to a position of 260-300, the fabric will not fall back.

When adjusting, pull the back cover of the machine head downwards to see the fabric feeding cam. Insert a screwdriver into the inside of the machine casing, loosen the screws of the fabric feeding cam, and then turn the screws to a position that is 260-300 degrees from the upper shaft curve, and then tighten the cam screws.