– 13 –
4-10. Adjusting the thread trimming device
1. The structure of the thread trimming device of this sewing machine is as shown in the
figure given below.
2. Adjusting the counter knife and moving
knife
1) The standard mounting position of the counter
knife and moving knife is the position at which
the center line of cutting portion of moving knife
is aligned with the center line of eye of counter
knife as illustrated in the figure.
2) If portion
ⓐ
of counter knife is larger than the
standard, three threads will be trimmed instead
of two threads in failure. If this phenomenon
occurs, threads will not be brought to the nor-
mal position after thread trimming. If potion
ⓑ
is larger than the standard, the knives cannot
trim the threads. It is therefore necessary to
adjust the knives to the correct position.
3. Adjusting the thread trimming cam crank
1) Align the thread trimming cam cranks, right and
left with the flat position of thread trimming cam
crank shaft in the arrangement as shown in the
figure.
2) Slowly turning thread trimming cam crank shaft
❶
, align stopper lever
❷
with the flat portion
on thread trimming cam crank shaft
❶
.
Thread trimming solenoid
Thread trimming
cam
Base of solenoid
connection link
Thread
guide
Counter knife
Moving
knife
Thread trimming
lever
Return spring
Return spring
Thread release
cable
Thread trimming
cam crank, left
Thread trimming cam
crank, right
ⓐ
ⓑ
Counter
knife
Moving
knife
Thread trimming
cam crank, left
Thread trimming
cam crank, right
Return
spring
Shaft sleeve
87.5 mm
❷
❶
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
