Troubles In Sewing And Corrective Measures - JUKI LZ-2290C-F Instruction Manual

10. TROUBLES IN SEWING AND CORRECTIVE MEASURES

Phenomenon
① When the thread gets entangled in the
Thread
breakage thread take-up lever.
② When the needle thread is threaded in a
wrong way.
③ When the thread gets entangled in the
sewing hook.
④ When the needle thread is excessively
tight or loose.
⑤ When the needle thread slips out of the
rotary disc.
⑥ When the tension of the thread take-up
spring is excessively high or low.
⑦ When the stroke of the thread take-up
spring is excessively large or small.
⑧ When the timing of the sewing hook and
the needle is not matched.
⑨ When there is a scratch on the thread path
of hook, bobbin case, thread take-up lever
or any other part.
⑩ When the thread is not suitable.
a. The quality of the thread is poor.
b. The thread is too thick for the needle.
c. The thread is broken by heat.
⑪ When the stitch is skipped.
① When the needle is inserted in a wrong
Stitch
skipping way.
a. The needle is not entirely inserted into
the needle bar.
b. The needle eye is not facing straight to
the operator.
c. The needle is facing backwards.
② When the needle itself is not suitable.
a. The needle is bent.
b. The quality of the needle is not good.
c. The needle is too thin for the thread.
d. Blunt needle is used.
③ When the hook blade point is not sharp
enough or damaged.
④ When the timing of the sewing hook and
the needle is not matched.
⑤ When the height of the needle bar is not
correct.
⑥ When the clearance between the needle
and the sewing hook is too great.
⑦ When the needle thread slips out of the
rotary disc.
(For optional auxiliary thread take-up lever
type only)
Cause
– 184 –
Corrective measures
○ Remove the entanglement.
○ Thread it correctly.
○ Remove the entanglement.
○ Adjust the thread tension.
○ Increase the tension of the preten-
sion disk.
○ Adjust the tension of the take-up
spring.
○ Adjust the stroke of the take-up
spring. (8 to 12 mm)
○ Adjust the timing.
○ Remove such a scratch or replace
the component.
○ Use a thread of good quality.
○ Use a suitable thread or needle.
○ Use JUKI Silicone Oil Lubricant unit.
○ Refer to the following paragraphs,
Stitch skipping.
○ Fully insert the needle.
○ Let the needle eye face straight to
the operator.
○ Let the long groove on the needle
face to the operator.
○ Replace it with a new needle.
○ Use a needle of good quality.
○ Use a suitable needle or thread.
○ Replace it with a new needle.
○ Resharpen the hook or replace it.
○ Adjust the timing properly.
○ Adjust the height of the needle bar.
○ Adjust the clearance.
○ Adjust the position of the auxiliary
thread take-up lever properly.
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