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5-1. Troubles and corrective measures (Sewing conditions)
Trouble
① Stitches are slipped at the start.
1. The needle thread
slips off at the
start of bar-tack-
② The needle thread remaining on the nee-
ing.
dle after thread trimming is too short.
③ The bobbin thread is too short.
④ Needle thread tension at 1st stitch is too
high.
⑤ Stitching pitch at 1st stitch is too small.
① The hook or the inner hook holder has
2. Thread often
breaks or syn-
scratches.
② The needle hole guide has scratches.
thetic fiber thread
splits finely.
③ Thread enters the groove in the hook.
④ The needle thread tension is too high.
⑤ The tension of the thread take-up spring
is too high.
⑥ The synthetic fiber thread melts due to
heat generated on the needle.
⑦ When taking up the thread, the needle
tip penetrates the thread.
① The needle is bent.
3. The needle often
② The needle comes in contact with the
breaks.
intermediate presser.
③ The needle is too thin for the material.
④ Clearance between the needle and the
hook is too small.
① The counter knife is dull.
4. Threads are not
② Knife pressure of the counter knife is
trimmed.
low.
③ The counter knife has been improperly
positioned.
④ The last stitch is skipped.
(Bobbin thread
only)
⑤ Bobbin thread tension is too low.
⑥ Flopping of cloth
① Clearance provided between the needle
5. Stitch skipping
often occurs.
and the hook is not correct.
② Position of the inner hook holder against
the needle is not correct.
③ The needle is bent.
④ The needle thread after thread trimming
is too long.
① The needle thread tension is not high
6. The needle thread
comes out on the
enough.
② The needle thread after thread trimming is
wrong side of the
material.
too long.
① The knife has been improperly position.
7. Threads break
at time of thread
trimming.
Cause
◦ Adjust the clearance provided between the nee-
◦ Set soft-start sewing at the beginning of sewing.
◦ Decrease the tension of the thread tension con-
◦ Increase the tension of the thread take-up spring.
◦ Decrease the bobbin thread tension.
◦ Increase the clearance between the needle and
◦ Decrease the needle thread tension at 1st stitch,
◦ Make the stitching pitch at 1st stitch longer.
◦ Decrease the needle thread tension at 1st stitch.
◦ Remove the hook and grind hook or the inner
◦ Buff the needle hole guide or replace it with a
◦ Detach the hook to remove the thread.
◦ Decrease the needle thread tension.
◦ Decrease the tension of the thread take-up
◦ Use the optional needle cooler.
◦ Check the rough state of needle tip.
◦ Use the ball-pointed needle.
◦ Replace the bent needle.
◦ Adjust the position of the intermediate presser.
◦ Replace it with a thicker needle according to the
◦ Adjust the clearance between the needle and the
◦ Replace the counter knife.
◦ Adjust the knife pressure of the counter knife.
◦ Correct the position of the counter knife.
◦ Correct the timing between the needle and the
◦ Increase the bobbin thread tension.
◦ Lower the intermediate presser height.
◦ Adjust the clearance between the needle and the
◦ Adjust the position of the inner hook holder
◦ Replace the bent needle.
◦ Decrease the tension of the thread take-up
◦ Increase the tension of the thread tension control-
◦ Increase the needle thread tension.
◦ Increase the tension of the thread tension control-
◦ Correct the position of the knife.
– 88 –
Corrective measures
dle and the hook.
troller No. 1.
the counter knife.
and extend the duration of the AT operation at the
beginning of sewing.
hook holder with a fine grind stone or buff them.
new one.
spring.
material.
hook.
hook.
hook.
against the needle.
spring.
ler No. 1.
ler No. 1.
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