−
62
−
2
.
Needle thread end rests on the
material at the start of sewing.
3. Thread slips off the needle eyelet
immediately atter thread trimming.
4. Thread breaks at the start of sewing.
2-1) Length of thread remaining at the
needle eyelet is excessive.
2-2) Top end of tangled-up thread on the
wrong side of the material appears on
the right side of the material.
3-1) The moving knife fails to separate the
threads and trims the thread at the
needle.
4-1) The needle thread feeding amount at
the time of thread trimming is
excessive. causing the thread to break
when the needle reaches the lowest
position of its stroke at the start of
sewing.
4-2) Stitch length is too short
1)-A Tension applied by the pre-tension disk is
too low.
1)-B Thread tmming cam timing has been
excessively retarded.
1)-A Thread trimming cam timing has been
excessively advanced.
1)-B Locus of the moving knife is defective.
2)-A The thread slacks because of small stitch
length.
2)-B The needle repeatedly enters the same
point since the stitch length is small.
2)-C Thread tension fluctuates because of
tangle-up thread.
Increase the tension applied by the pre-tension disk.
Adjust the thread trimming cam timing to the correct value.
Place the needle thread under the presser foot at the start of sewing, thereby preventing the
thread from being tangled up. (Particularly when reverse feed stitches are made at the start of
sewing)
Properly adjust the thread trimming cam timing.
Re-install the knife unit or replace the knife unit with a new one.
Reduce the needle thread feeding amount.
To start sewing with a small stitch length, place the needle thread end under the presser foot
and start the sewing machine.
Trouble
Cause 1
Cause 2
Corrective measure and adjusting procedure
