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Adjustment procedures
Results of Improper adjustment
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.
o
If dimension
E
is too small, an
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.
o
On the contrary, if dimension
E
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.
o
Excessive clearance will cause
stitch skipping.
o
Insufficient clearance will cause
the upper looper to come in con-
tact with the lower looper
❺
.
