JUKI LU-2800 Series Engineer's Manual page 63

Adjustment procedures
5) Position of the thread trimmer cam
Loosen setscrews ❻ of the thread trimmer cam and clamping
1.
screw ❼ of the lower shaft set collar.
2. Set the thread trimmer solenoid to initial position.
3. Adjust so that the clearance between the thread trimmer cam
roller  and dwell section of the thread trimmer cam  is 0.1
± 0.05 mm in the state that the moving knife driving arm link ❽
is in contact with the moving knife driving arm roller ❾ . Then
tighten setscrews ❻ of the thread trimmer cam.
Make the lower shaft set collar  come in close contact with
4.
the thread trimmer cam  , then securely tighten clamping
screw ❼ of the lower shaft set collar.
6) Adjusting the knife pressure
Knife pressure
o
Loosen setscrews ❶ of the moving knife.
1.
Adjust the installing position of the moving knife ❷ so that the
2.
position where moving knife ❷ and counter knife ❸ start com-
ing in contact with each other starts at the position of Dimen-
sion E from the top end of the moving knife ❷ .
At this time, if moving knife ❷ comes in contact with the clamp
spring, the knife pressure is increased by the clamp pressure.
So, adjust the knife pressure in the state that the clamp pres-
sure is not applied to the knife.
Tighten setscrews ❶ of the moving knife.
3.
(Caution) Operate the sewing machine with the knife pressure
minimized to such an extent that both needle and
bobbin threads can be trimmed.
Initial position
o
Loosen clamping screw ❹ of the moving knife driving arm.
1.
2. Adjust so that the distance between the top end of the counter
knife ❸ and the top end of the moving knife ❷ is Dimension F
when moving knife ❷ travels to its back end.
Tighten clamping screw ❹ of the moving knife driving arm so
3.
that there is no thrust play at the moving knife shaft ❺ .
Results of Improper adjustment
When there is no clearance be-
tween the thread trimmer cam 
and the thread trimmer cam roller
 :
Thread trimmer cam  inter-
o
feres with the thread trimmer
cam roller  resulting in break-
age or machine lock.
When the clearance between the
thread trimmer cam  and the
thread trimmer cam roller  is
large :
Defective thread trimming will
o
result.
When the knife pressure is high :
Blade sections of the counter
o
knife ❸ and the moving knife ❷
may be damaged.
Torque at the time of thread
o
trimming is increased resulting in
motor-stop.
Defective thread trimming opera-
o
tion will result.
When the knife pressure is low :
Defective thread trimming will
o
result.
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