DEFECTS 


  1. As the finish of stitching, if needle thread is pulled, ravelling appears Thread breaks at the second barred end
  2. At the finish of stitching, if bobbin thread is pulled, ravelling appears At the second barred end, bobbin thread appears on the upper surface of the cloth
  3. At the first barred end, needle thread comes out to the back of cloth At the first barred end, needle thread breaks
  4. At first barred end, bobbin thread appears an upper surface of the cloth
  5. Stitching wobbles at seaming
  6. Needle thread breaks at seaming
  7. Thread slips at start of sewing
  8. Thread wobbles at start of sewing 

Reasons 

  1. Tension disc No. 1 too weak Tension disc No. 1 too weak, so double hooking at the tip of the hook point
  2. Tension disc No. 3 too strong Bobbin thread tension too weak
  3. Tension disc No. 3 too weak Bobbin thread tension too strong
  4. Tension disc No. 3 too strong Bobbin thread tension too weak
  5.  Tension disc No. 2 too weak If defects No. 1, No. 3, appear their tension disc too strong Thread take-up spring not strong enough and moving range inadequate Bobbin thread tension too strong
  6.  Tension disc No. 2 too strong Tension of thread tension disc and moving range of take-up spring too strong and too wide, respectively
  7. Insufficient drawing out of thread Bobbin thread tension too weak Tension of tension disc No. 3 too strong
  8. Too much thread drawing out Tension disc No. 3 too weak