JUKI LBH-1700 Series Engineer's Manual page 35

Adjustment Procedures
1. Loosen the setscrew in the bobbin thread trimmer link rod in
the state that the presser lifting lever has returned, turn the
bobbin thread trimmer link rod and adjust the distance from
the bobbin thread trimmer to the center of the knife groove to
2 to 3 mm to securely trim the bobbin thread.
2. After trimming the bobbin thread, when the bobbin thread is
not retained, adjust the position of the clamp plate to such an
extent that the plate does not overlap with the needle hole.
<Check after the adjustment>
™ Make sure that the bobbin thread trimmer securely trims the
bobbin thread and retains it when the presser lifting lever
comes down.
™ For the sewing machine equipped with the auto-lifter, open
the trimmer after the adjustment, and re-check the closing
amount of the bobbin thread trimmer by presser lifting action.
™ Adjust the opening amount of the trimmer so that you turn
the bobbin thread trimmer actuating cam.
™ Adjust the opening timing of the trimmer by moving the bobbin
thread trimmer actuating cam to the right or left.
™ Adjust the distance from the bobbin winder trip latch to the
hook sleeve so that you turn the bobbin winder trip latch lever.
™ Loosen the bobbin winder trip latch shaft and adjust the bobbin
winder trip latch stopper for the protruding amount of the inner
hook of bobbin winder trip latch when lifting the presser.
(Caution) If opening timing of the bobbin thread trimmer is
too early and the opening amount is large, the
trimmer may open when the presser lifting lever
has returned. Lower the presser lifting lever by
hand, release your hand in this state, and make
sure that the trimmer does not open.
Results of Improper Adjustment
™ When the distance from the bobbin
thread trimmer to the knife groove
is excessively large, the trimmer
may not fully close.
™ When the distance from the bobbin
thread trimmer to the knife groove
is excessively small, the trimmer
and the cloth cutting knife may
come in contact with each other.
™ If the opening amount of the bobbin
thread trimmer is small, the bobbin
thread may not be trimmed.
™ If the opening amount of the bobbin
thread trimmer is large, the trimmer
overlaps with the needle hole and it
may come in contact with the
needle.
™ If the opening timing of the bobbin
thread trimmer is excessively
advanced, slip-off of thread at the
start of sewing may occur.
™ If the opening timing of the bobbin
thread trimmer is excessively
retarded, the fabric may be drawn.
™ If the distance from the bobbin
winder trip latch to the hook sleeve
is small, the latch comes in contact
with the hook sleeve when the
sewing machine is running. As a
result, the latch will be deformed.
™ If the adjustment of the bobbin
winder trip latch stopper is improper,
b o b b i n m a y r u n i d l e w h e n
performing thread trimming.
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