JUKI lbh-1790 series Engineer's Manual page 23

Adjustment Procedures
1. Start up 3) Needle thread trimming adjustment mode and set
the trimmer to thread trimming position (40).
2. Loosen setscrews 1 and adjust so that the longitudinal position
of the trimmer is set to 0 to 3 mm from the center of the needle
hole at the time of needle thread trimming.
3. Adjust needle thread trimmer guide shaft 3 in the direction of
the arrow mark so that needle thread trimmer guide shaft 3
comes in contact with arm B 2 at the time immediately before
the needle thread trimmer is fully closed.
1. Start up 3) Needle thread trimming adjustment mode and set
the trimmer to waiting position (10).
2. Loosen setscrews 1 and adjust so that opening amount of
the trimmer is 3 to 5 mm when the needle thread trimmer is in
the waiting position during sewing.
(Caution) Check that the trimmer securely releases needle
thread when it retreats to the extreme end.
Increase the opening amount when needle thread
is not released.
Results of Improper Adjustment
™ If the adjustment is improper,
needle thread is missed at the
time of trimming and cannot be
trimmed. Besides, the trimmed
needle thread may not be
caught.
™ When the opening amount of
trimmer is narrow, needle thread
is not released at the start of
sewing and needle thread may
protrude.
™ When the opening amount of
trimmer is narrow, needle thread
may be missed at the time of
trimming.
™ When the opening amount of
trimmer is excessively large, the
trimmer opens and needle
thread may slip off when the
presser is lifted.
™ When the opening amount of
trimmer is excessively large, the
trimmer exceeds the motion
range and step-out of needle
thread trimmer motor may occur.
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