23. Troubles In Sewing And Corrective Measures - JUKI DNU-1541 Manual De Instrucciones

23. TROUBLES IN SEWING AND CORRECTIVE MEASURES

Troubles
1. Thread breakage
(Thread frays or is
worn out.)
(Needle thread trails 2
to 3 cm from the wrong
side of the fabric.)
2. Stitch skipping
3. Loose stitches
46
Causes
1 Thread path, needle point, hook blade
point or bobbin case resting groove on
the throat plate has sharp edges or burrs.
2 Needle thread tension is too high.
3 Needle comes in contact with the blade
point of hook.
4 Amount of oil in the hook is too small.
5 Needle thread tension is too low.
6 Thread take-up spring works excessively
or the stroke of the spring is too small.
7 Timing between the needle and the hook
is excessively advanced or retarded.
1 Timing between the needle and the hook
is excessively advanced or retarded.
2 Pressure of the presser foot is too low.
3 The clearance provided between the
top end of the needle eyelet and the
blade point of hook is not correct.
4 Improper type of needle is used.
1 Bobbin thread does not pass through
the tension spring of the bobbin case.
2 Thread path has been poorly fi nished.
3 Bobbin fails to move smoothly.
4 Bobbin thread tension is too low.
5 Bobbin has been wound too tightly.
6 Needle tip is worn out.
Corrective measures
™ Remove the sharp edges or burrs on the
blade point of hook using a fi ne emery
paper. Buff up the bobbin case resting
groove on the throat plate.
™ Decrease the needle thread tension.
™ Refer to "17. NEEDLE-TO-HOOK
RELATION."
™ Adjust the amount of oil in the hook
properly.
Refer to "5. LUBRICATION".
™ Increase the needle thread tension.
™ Decrease the tension of the spring and
increase the stroke of the spring.
™ Refer to "17. NEEDLE-TO-HOOK
RELATION."
™ Refer to "17. NEEDLE-TO-HOOK
RELATION."
™ Tighten the presser spring regulator.
™ Refer to "17. NEEDLE-TO-HOOK
RELATION."
™ Replace the needle with one which is
thicker than the current needle by one
count.
™ Refer to "7. THREADING THE BOBBIN
THREAD".
™ Remove rough parts with a fi ne emery
paper or buff it up.
™ Replace the bobbin or hook with a new
one.
™ Increase the bobbin thread tension.
™ Decrease the tension applied to the
bobbin winder.
™ Replace the needle.