Failure Causes of overlock sewing machine and the Countermeasures(Ⅳ)

Broken chain hook thread of an overlock sewing machine 

1. Error in seam threading or the threading device is not smooth; Remove the burr of the threading device to make it smooth, Threading as required;

2. The feeding dog has sharp edges; Grind or polish the sharp edge;

3. There are scars on the tip of the needle; Replace the needle with a new one;

4. There are scars on the pick-up cam; Grinding and polishing take-up cam;

5. Improper position of take-up cam; Adjust its position ;

 Broken chain thread machine needle thread of an overlock sewing machine

1. Incorrect positioning of machine needle and chain thread crochet; Readjust its position;

2. The pressure of needle and thread clamping plate of chain sewing machine is too tight; Loosen the needle thread clamp nut of chain thread machine;

3. The distance between the needle tip of chain thread crochet and machine needle is too large; Loosen the positioning screw of chain thread crochet, turn the chain thread Crochet to make it close to the machine needle, and tighten the positioning screw;

4. Machine needle bending or needle tip burr, exchange machine needle;

5. The needle groove of the machine is in the wrong direction; Adjust the direction of the needle slot so that the long slot of the needle is aligned with the operator;

6. Chain thread crochet needle is blunt; Sharpen the crochet needle or replace one;

7. The chain wire needle guard frame is not aligned; Adjust the position of the chain thread needle guard to make it close to the machine needle;

Machine needle thread tight when an overlock sewing machine runs 

1. Insufficient thread take-up and outgoing line on the needle; Move the thread take-up on the needle bar out a little so that each needle can send enough thread;

2. The pressure of needle and thread clamping plate is too tight; Loosen the nut of needle thread clamping plate of the machine;

3. Too much outgoing line of lower bending needle or too loose pressure of lower bending needle thread clamping plate; Reduce the outlet quantity of the lower bending needle or tighten the clamp nut of the lower bending needle;

Loose stitches at the time of oversewing 

1. The pressure of needle and thread clamping plate is too loose; Tighten the needle clamp nut;

2. Too much needle and thread outgoing line; Adjust needle take-up bar;

3. The pressure of the lower bending needle thread clamping plate is too tight, resulting in the machine needle thread being pulled down; Loosen the thread clamp nut of the lower bending needle or adjust the thread take-up rod of the lower bending needle;