JUKI LU-2860V-7, Instruction Manual

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Troubles Causes Corrective measures
4. Thread slips off
the needle eyelet
simultaneously with
thread trimming.
① Thread tension given by the tension
controller No. 1 is too high.
② Thread take-up spring stroke is too large.
○ Decrease the thread tension given by the
tension controller No. 1.
○ Decrease the stroke.
5. Thread slips off the
needle eyelet at the
start of sewing.
① Thread tension given by the tension
controller No. 1 is too high.
②
Clamp spring has improper shape.
③ Bobbin thread tension is too low.
④ Thread take-up spring stroke is too large.
○ Decrease the thread tension given by the
tension controller No. 1.
○
Replace the clamp spring with a new one or
correct the current one.
○ Increase the bobbin thread tension.
○ Decrease the stroke.
6. Faulty intertwining of
the needle thread and
bobbin thread at the
beginning of sewing.
① The bobbin thread clamp pressure is
high.
○ Decrease the bobbin thread clamp pressure.
Refer to "8-5. Adjusting the position of
counter knife, knife pressure and clamp
pressure" p.110
.
○ Hold the needle thread on the material.
7. Thread is not cut
sharply.
① The blades of moving knife and counter
knife have been improperly adjusted.
② The knives have blunt blades.
③
Bobbin thread tension is too low.
○ Refer to "8-5. Adjusting the position of
counter knife, knife pressure and clamp
pressure" p.110
.
○ Replace the moving knife and counter knife
with new ones, or correct the current ones.
○
Increase the bobbin thread tension.
8. Thread remains uncut
after thread trimming.
(Bobbin thread
trimming failure
when stitch length is
comparatively short.)
① Initial position of the moving knife has
been improperly adjusted.
② Bobbin thread tension is too low.
○ Refer to "8-5. Adjusting the position of
counter knife, knife pressure and clamp
pressure" p.110
.
○ Increase the bobbin thread tension.
9. Thread breaks at the
start of sewing after
thread trimming.
① The needle thread is caught in the hook. ○ Shorten the length of thread remaining on the
needle after thread trimming.
Refer to "4-1. Thread tension" p.33 .
10. When a heave-weight
material is sewn, the
material warps.
① The feed amount of the top feed is
inadequate.
○ Decrease the feed dog height and reduce
the feed amount of the bottom feed. (Refer
to the Engineer's Manual for the adjustment
procedure.)