Sewing material moving irregularly

During the sewing process using the sewing machine, there are sometimes irregularities in the speed at which the sewing material moves, and the stitching time is short and short. The sewing material is moved forward by the cooperation of the feed dog and the presser foot. Therefore, when the above irregular movement of the sewing material occurs, we can conclude that the tooth and the presser foot have failed or the pressure is improperly adjusted.

For example, the presser foot pressure is too small. If the pressure is not tight, it will cause irregular movement. At this time, we only need to rotate the pressure regulating screw downward to compress the sewing material. Another example is that the presser foot is too high to press the sewing material, and the sewing material can move freely or not at all.

Specific adjustment method: When adjusting, we first lift the presser foot wrench, loosen the guide screw, and then press the presser foot from top to bottom to adjust the distance between the presser foot and the needle plate to 7-8 mm height. Then tighten the screws and drive.

In addition, there is another reason for the author's analysis. Because the tooth screws are loose, the teeth are shaken left and right during operation, so that the sewing material cannot move forward regularly.

To do this, we removed the needle plate and tightened the two teeth. After tightening, we installed the needle plate and checked whether the teeth on both sides of the tooth are rubbed against the edge of the needle plate groove. If there is friction, it will cause noise and weight. At this time, only the needle plate is removed and the teeth are loosened. Screw, adjust the position of the tooth to the middle of the needle plate slot, tighten the tooth screw, and then install the needle plate.

Sewing material backwards

In the sewing work, sometimes the sewing material does not move forward, but instead moves toward the operator, that is, the sewing material is retracted. This failure is caused by the misalignment of the upper shaft crank and the cam eccentric screw.

The reason why the teeth of the feeding mechanism can move forward rhythmically is completely by the movement of the feeding cam. Because the cam itself is eccentric, the fork is moved back and forth, and the fork drives the feed shaft and the carriage to promote the reciprocating motion of the teeth. It can be seen that the eccentric position of the cam is very important.

The standard angle of the upper shaft crank and the cam screw. We only need to adjust the angle between the cam screw and the upper shaft crank to 260 degrees -300 degrees, the sewing material will not retreat.

Specific adjustment method: When adjusting, we can open the back cover of the machine head and you can see the feeding cam. Insert the screwdriver into the inside of the casing, loosen the feeding cam screw, and then turn the screw to the upper shaft. In a position of 260 degrees - 300 degrees, tighten the cam screw.