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Adjustment Procedures Results of Improper Adjustment
1. Loosen setscrew 1 in the moving knife.
2. Select moving knife base thrust plate 2 so that the clearance
between the top surface of the bobbin case and the bottom
face of the moving knife is 1.3 ± 0.1 mm.
3. After the adjustment, tighten setscrew 1.
Adjusting the knife pressure
1. Move moving knife 1 to the front end by hand.
2. Loosen setscrews 3 in the fixed knife and move the fixed knife
to the left or right to adjust the position.
3. To adjust the knife pressure, move fixed knife 2 and adjust so
that the knife pressure starts from the position where the
distance from the top end of the moving knife to the top end of
the fixed knife is 5 to 6 mm.
(Caution)
1. Adjust the clearance between the fixed knife and the
clamp spring to 1.6 ± 0.1 mm.
2. Reduce the knife pressure as low as possible to such
an extent that the needle and bobbin threads are cut
together.
™ Initial position
™ When the play at the top end of the moving knife is 0 to 1
mm, the distance from the top end of the moving knife to
the top end of the fixed knife is 0 to 0.5 mm when the moving
knife travels to the rear end.
™ Loosen setscrew 4 in the moving knife arm and move the
moving knife base to adjust the initial position.
When the knife pressure is
excessively high :
™ Blade sections of the fixed knife
and the moving knife may be
damaged.
™ Torque at the time of thread
trimming becomes large. As a
result, machine lock will result.
™ Defective thread trimming action
will result.
When the knife pressure is
excessively low :
™ Defective thread trimming will
result.
When the engagement of the blade
faces of the moving knife and the
fixed knife is not proper :
™ Thread trimming will be dull.
When the clearance is larger than
the specified value :
™ Defective catching of needle
and bobbin threads will result.
When the clearance is smaller than
the specified value :
™ There is no space where the
thread enters in between the
moving knife and the bobbin
case. As a result, defective
thread trimming will result.
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