The sewing is normal on the flat fabric. When the thick material is sewn, or the needle is jumped uphill or downhill, the reason is that when the presser foot is pressed obliquely on the thick material, the presser foot is too long, and the center of the presser foot is raised. The thick material is lifted up, so that the center of the presser foot cannot press the fabric, so that the needle can not form a loop under the needle plate to generate a jump stitch.

(1) If only one shot is occasionally skipped, the operator can adjust it himself. If there is a thick material protruding, use the left and right hands to pull the fabric to the left and right hands, and keep up with the rhythm of the feeding movement. Thick material is sent over the presser foot. When the upper and lower slopes are tightened by the hand, the needle can form a loop when the needle is not pressed, which can solve the upslope problem.

(2) If the upper and lower slope jumpers are more serious, only the rear part of the presser foot can be worn away by the grinding wheel, so that when the presser foot is up and down, the presser foot is shorter than the original one, and the loop is formed. It is better.

(3) If there is a 1~2 needle jumper when going downhill, use your finger to press down on the front side of the presser foot to make the presser foot tightly press the fabric to form a good loop. It is also possible to slightly slant the beveled edge of the front side of the presser foot so that the presser foot can press the fabric to produce a loop when going downhill.

(4) If the needle jumps when entering a thick material, the cooperation between the hook and the needle is too late or too early, because the thin wire loop is formed well. When the material is thick, the needle thread passes through the thick line. After the material is raised, when the wire loop is formed, the thick material brings the wire too tightly, so that the wire loop is formed later than originally. The position that has been proofread, because the loop is formed late, the hook tip has crossed the hook line position, causing the jump stitch that cannot be hooked to the loop. Simply re-adjust the fit time of the hook and the needle to delay the hook hook time slightly.

(5) Jumping needle problem In addition to the cooperation of the hook and the hook line time when going uphill, it is also necessary to pay attention to the gap fit between the needle and the hook when thick and thin, and it can be solved by adjusting the double needle machine.