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2. Needle thread is likely to slip off
2-1) Needle thread slips off the needle eyelet
1-A) Length of thread trailing from the needle
Refer to Cause (1)-1)-A through F and [3.-(11)-7),
the needle eyelet.
immediately after thread trimming.
eyelet after thread trimming is too short.
8) and -(12)-11) Thread Trimmer Cam].
2-2) Needle thread slips off the needle eyelet
2-A) Length of thread trailing from the needle
Refer to Cause (1)-1)-A through F and [3.-(11)-7),
at the start of sewing.
eyelet at the sewing start is too short.
8) and -(12)-11)Thread Trimmer Cam].
3. Thread Trimming Failure
3-1) The thread trimmer fails to cut the threads.
1-A) The moving knife blade fails to match the
Check the height of the moving knife and counter
counter knife blade in height and direction.
knife.
1-B) The moving knife blade and counter knife
Replace the moving knife and the counter knife
blade have worn out or been damaged.
with new ones.
1-C) The counter knife fails to provide
Re-adjust the knife pressure. (Refer to [3.-(10)-3) ,
sufficient pressure.
(11)-3) and -(12)-7) Knife Pressure]).
1-D) Weak thread tension
Increase the tension of needle thread and bobbin thread.
1-E) Inadequate mounting position for the
Make readjustments. Refer to [Needle Thread
thread guide
Trimming Device].
3-2) Single yarn of the thread remains
2-A) The moving knife blade and the counter
Replace the moving knife and the counter knife
untrimmed.
knife blade have worn out or been damaged.
with new ones.
2-B) The moving knife blade fails to match the
Check the height of the moving knife and counter
counter knife blade in height and direction.
knife.
2-C) Timing of thread trimming is too late.
Check the cam for correct timing.
2-D) The counter knife fails to provide a
Re-adjust the knife pressure. (Refer to [3.-(10)-3) ,
sufficient pressure.
(11)-3) and -(12)-7) Knife Pressure].
3-3) The moving knife stops during thread
3-A) Thread used is too thick.
Use the specified thread.
trimming.
3-B) Clearance between the moving knife blade
Check the lateral position of the moving knife and
(outside) and the throat plate is too small.
adjust it correctly.
3-C) Needle thread tension is too high.
Decrease the thread tension controlled by the
tension controller No. 1.
3-D) Needle thread tension is too low.
Increase the thread tension controlled by the
tension controller No. 1.
3-E) The bobbin thread tension is too high.
Reduce the bobbin thread tension.
3-F) The pressure of the counter knife is too high.
Adjust the counter knife position.
3-G) The initial position of the moving knife
Check the initial position of the moving knife and
is too advanced.
adjust it.
3-H) The thread trimming knives are not sharp
Refer to Cause 3-1) and 2) for the knife pressure
enough.
and thread trimmer cam.
Trouble
Cause (1)
Cause (2)
Check Procedure and Corrective Measures
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