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7. THREAD TRIMMING TROUBLES AND THE CORRECTIVE MEASURES
Troubles Causes Corrective measures
1. Thread is not trimmed.
The needle does not come down into
the correct point of a button hole.
The final stitch is skipped.
The height of the thread separating claw
of the moving knife is not correct.
Correct the position on the looper.
Refer to the clause “2. (2) Positioning the needle
and the looper” (page 2).
Correct the position of the moving knife.
Refer to the clause “3. (3) Adjusting the position of
the moving knife” (page 18).
Make readjustment by the button clamp holder.
The thread separating claw of the
moving knife fails to separate the thread
on a fabric from that on the needle.
Correct the height of the thread separating claw of
the moving knife.
Refer to the clause “3. (4) Adjusting the height of
the thread separating claw of the moving knife”
(page 18).
2. Both the thread on the
needle and that on the
wrong side of a fabric
are trimmed.
Improper height of the thread separating
claw of the moving knife.
Improper height of the thread separating
claw of the moving knife.
Correct the position of the moving knife at the time
of completion of the stop motion.
Refer to the clause “3. (3) Adjusting the position of
the moving knife” (page 18).
Correct the height of the thread separating claw of
the moving knife.
Refer to the clause “3. (4) Adjusting the height of
the thread separating claw of the moving knife”
(page 18).
Correct the position of the moving knife.
Refer to the clause “3. (3) Adjusting the position of
the moving knife” (page 18).
Readjust the lift.
Refer to the clause “2. (6) Lift and pressure of the
button clamp” (page 8).
3. The trimmed thread on
the wrong side of a
fabric is too long.
The trimming timing of the moving knife
is bad.
The lift of the button clamp is too large.
(Caution) Perform the adjustment dimension of the position of the moving knife (adjustment) within
the range described in the table below.
If the adjustment value is smaller, the moving knife will overrun at the time of the stop
motion, and the thread separating claw will hit the fixed knife or the yoke slide insert,
resulting in damaged thread separating claw of the moving knife. On the other hand, if it
is larger, the thread separating claw may come in contact with the positioning finger yoke
slide while the machine is running, also causing breakage of the thread separating claw.
Moving knife position (adjustment) dimension
12 to 13 mm
15 to 16 mm
10.5 to 12.5 mm
Model
MB-373
MB-373-11
MB-377
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