JUKI MO-6800S Series Engineer's Manual page 23

Adjustment procedures
1) The relationship between the needle and the upper looper
1. Loosen the clamping screw ❷ at the top end of upper looper
bracket ❶ to adjust dimension E.
2. When performing the above adjustment, pay attention also to
the clearance produced between the upper looper and the lower
looper ❺ at the time of their crossing.
2) The relationship between the upper looper and the lower
looper
1. Loosen the clamping screw ❷ at the top end of upper looper
bracket ❶ to move the upper looper ❸ back or forth for position-
ing the clearance of 0.05 to 0.2 mm between the upper looper ❸
and the lower looper ❺ at the time of their crossing.
(Caution) The upper looper ❸ and the lower looper ❺ shall not
either touch nor collide to each other.
Results of Improper adjustment
If dimension E is too small, an
o
excessive clearance will be pro-
duced between the upper looper
❸ and the needle ❹ . As the
result, the upper looper thread
will fail to catch the needle ❹ ,
and stitch skipping occurs.
On the contrary, if dimension E
o
is too large, the needle tip will
hit the upper looper ❸ , causing
needle breakage. Also the loop-
er will touch other component
when the presser foot goes up.
Excessive clearance will cause
o
stitch skipping.
Insufficient clearance will cause
o
the upper looper to come in con-
tact with the lower looper ❺ .
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