Others; Troubles In Sewing And The Corrective Measures - JUKI Sewing Machine Instruction Manual

25. otHErS

25-1 troubles in sewing and the corrective measures

troubles
1. Thread breakage
2. Stitch skipping
3. Loose stitches
4. Thread slips off the needle
eyelet simultaneously with
thread trimming.
5. Needle thread is not
rimmed. Bobbin thread is
trimmed.
6. Both needle thread and
bobbin thread are not
trimmed.
7. Thread is not cut sharply.
8. Material bends.
9. Feed pitch is not obtained.
10. Shirring is not performed.
11.Shirring is excessively
performed.
Causes
1 Thread path, needle point, hook blade point
or bobbin case resting on the throat plate
has sharp edges or burrs.
2 Needle thread tension is too high or too low.
3 Needle comes in contact with the blade point
of hook.
4 Thread take-up spring works excessively or
the stroke of the spring is too small.
5 Timing between the needle and the hook is
excessively advanced.
6 Bobbin idling amount is too large.
1 The clearance provide between the needle
and the blade point of hook is too large.
2 Timing between the needle and the hook is
excessively advanced or retarded.
3 Pressure of the presser foot is too low.
4 Height of the walking foot or presser foot is
too high.
1 Bobbin thread is not put in the fork end of the
thread tension spring of the bobbin case.
2 Thread path has been poorly finished.
3 Bobbin fails to move smoothly.
4 Bobbin thread tension is too low.
5 Bobbin has been improperly wound.
1 Returning force of the thread take-up spring
is too strong.
2 Thread tension given by the thread tension
controller No. 1 is too high.
3 Position of the counter knife is improper.
1 Stitch skipping at the last stitch (Clearance
provided between the needle and the hook is
excessive.)
1 Thread trimming timing is improper.
2 Breakage of the knife
3 Pressure of the knife is insufficient.
4 Moving amount of the moving knife is
insufficient.
1 Thread trimming timing is improper.
2 Pressure of the knife is insufficient.
3 The knife has a blunt blade.
1 Top feed belt is bent.
2 Height of the main walking foot and the
auxiliary walking foot is improper.
3 Auxiliary feed shirring amount set value is
improper.
1 Feed belt has been worn out.
2 Walking foot is excessively raised.
3 Belt tension is too low.
1 Feed belt has been worn out.
2 Walking foot is excessively raised.
3 Belt tension is too low.
4 Set value is too small.
1 Set value is too large.
™ Remove the sharp edges or burrs on the blade point of
hook using a fine emery paper. Buff up the bobbin case
resting groove on the throat plate.
™ Adjust the needle thread tension.
™ Refer to "Adjusting the needle and the hook".
™ Decrease the tension of the thread take-up spring and
increase the stroke of the spring.
™ Refer to "Adjusting the needle and the hook".
™ Increase the spring pressure.
™ Refer to "Adjusting the needle and the hook".
™ Refer to "Adjusting the needle and the hook".
™ Tighten the presser spring regulator.
™ Refer to "Adjusting the height of the walking foot and
the presser foot".
™ Thread the bobbin case properly.
™ Grind the thread path using a fine emery paper. Buff up
the thread path.
™ Replace the bobbin.
™ Adjust the bobbin thread tension.
™ Refer to "Winding a bobbin".
™ Refer to "Threading the machine head".
™ Refer to "Threading the machine head".
™ Refer to "Adjusting the thread trimmer".
™ Refer to "Adjusting the needle and the hook".
™ Adjust the thread trimming timing.
™ Replace the knife.
™ Adjust the pressure of the knife.
™ Adjust the initial position of the moving knife.
™ Adjust the thread trimming timing.
™ Adjust the pressure of the knife.
™ Replace the knife.
™ Adjust the walking foot.
™ Make the height of the main walking foot and the
auxiliary walking foot same.
™ Adjust the set value.
™ Replace the belt.
™ Refer to "Adjusting the height of the walking foot".
™ Adjust to the proper tension value.
™ Replace the belt.
™ Refer to "Adjusting the height of the walking foot".
™ Adjust to the proper tension value.
™ Adjust to the optimum set value.
™ Adjust to the optimum set value.
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Corrective measures