JUKI MOL-254 Engineer's Manual page 49

Adjustment Procedures
1) Align the lower engraved marker line with the end face of
the bushing referring to the height of the needle bar ① of
the standard adjustment.
2) Loosen setscrew
direction of rotation and the longitudinal direction.
(Caution) Be sure to turn the inner hook in the direction
of the arrow mark as shown in (Fig. 2) when
performing the adjustment of the inner hook
timing.
4) Loosen setscrew in the shuttle and turn eccentric shaft
to adjust the clearance.
5) Loosen setscrew in the shuttle and adjust the clearance.
Take care when adjusting the clearance provided between
the needle and the blade point of the inner hook of the
item 4).
(Caution) The clearance provided between the inner hook
and the shuttle driver in the direction of rotation
is 0.5 mm to 0.7 mm as shown in (Fig. 2).
Tap section
After performing the adjustment, make sure
that the upper and lower clearances of section
in terms of the inner hook are equal.
in the shuttle driver and adjust the
to adjust the clearance.
Fig. 6
42
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Results of Improper Adjustment
1) For floppy materials, slightly
retard the hook timing. On the
contrary, for heavy-weight
materials, slightly advance the
hook timing. (For the prevention
of stitch skipping)
2) I f t h e c l e a r a n c e p r o v i d e d
between the needle and the
shuttle driver is larger than 0
mm, the needle is bent in the
direction of the blade point of the
inner hook. As a result, the blade
point of the inner hook and the
needle will be damaged. On the
contrary, if the clearance is
smaller, stitch skipping will
occur.
3) I f t h e c l e a r a n c e p r o v i d e d
between the needle and the
blade point of the inner hook is
larger than 0.05 to 0.1 mm, stitch
skipping will occur. On the
contrary, if it is smaller, the
needle and the blade point of the
inner hook come in contact with
each other, and scratch on them
will occur resulting in thread
breakage or hangnail.
4) I f t h e c l e a r a n c e p r o v i d e d
between the the side face of the
needle and the shuttle is smaller
than 7.5 mm, needle thread
spreading becomes insufficient.
As a result, a phenomenon that
needle thread is caught in the
inner hook is likely to occur.
5) I f t h e c l e a r a n c e p r o v i d e d
between the inner hook and the
shuttle driver is larger than 0.5
mm to 0.7 mm, hook noise will
be increased. On the contrary, if
it is smaller, thread, when thick
thread or the like is used, will fail
to smoothly come out of the
hook. As a result, defective
thread tightness will occur.
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