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Trouble
Cause (1)
Cause (2)
Check and corrective measures
From the previous page
4-2) The blade portion of the
knife is blunt.
2-A) The blade portions of the moving
and counter knives are not per- feat-
ly aligned at thread trimming. (The
mounting angle, position, and blade
inclination of the counter knife are
not matched with those of the moving
knife.)
Remove the throat plate, and
manually operate the thread
trimmer to cut about three cotton
thread #50. When all the three
threads are cut evenly, no further
corrective action is required. If
not;
Sharpen the
counter knife.
Correct the tilt of
the blade tip of
the counter knife.
Correct the
position of the
counter knife.
5. The bobbin thread is un-
trimmed. (But the needle
thread is trimmed.)
5-1) The backward movement
of the moving knife is
insufficient.
1-A) The backward movement of the mov-
ing knife is inappropriately adjusted.
(The position of the knife operation
axis or the thread trimming cam in the
right-left direction is inappropriately
adjusted.)
Measure the backward movement length of the moving
knife.
Adjust the position of the thread trimming cam in the
right-left direction to set the backward movement
length of the knife to within 2 to 2.5 mm (SH:2.5 to
3.0mm) if the measurement result is out of the range.
5-2) The position of the bobbin
thread at thread trimming
is unstable.
2-A)
A hook other than the specified hook is
used.
Check whether the current hook has a guide slit for the
bobbin thread.
If the hook has no such a slit, replace the hook with a
hook for threat trimming.
