Corrective measureCauseTrouble
1.Remove the scratches on the hook
point using a fine emery paper.
2.Decrease the tension and increase
the stroke of the thread take-up
spring.
3.Refer to (5.Needle-to-hook
relationship).
4.Adjust the needle thread tension
properly.
5.Refer to (5.Needle-to-hook
relationship)
6.Refer to (5.Needle-to-hook
relationship)
1.Refer to (7.Threading the machine
heads).
2.Remove the scratches on the hook
point using a fine emery paper.
3.Refer to (5.Needie-to-hook
relationship).
4.Refer to (5.Needie-to-hook
relationship).
5.Tighten the pressure regulator.
6.Replace the needie with one which
is one count thicker.
1.Properly thread the bobbin case.
2.Grind it using a fine emery paper
or buff it up.
3.Replace the bobbin or the bobbin
case.
4.Decrease the bobbin thread
tension.
5.Increase the bobbin thread
tension.
6.Slightly lower the sewing speed.
(1800 s.p.m)
7.Replace with a needle which is
thicker by one.
3.Loose stitches(lsolated
idling loops)
1.Stitch skipping
2.Thread breakage
①
The machine head has not been
properly threaded.
②
The hook has scratches.
③
The timing between the needie and
hook is too early or too late.
④
the clearance between the needil
and the hook point is too large.
⑤
The presure of the presser foot is
too low.
⑥
The needle number selected is
improper.
①
The hook has scratches.
②
The returning force of the thread
take-up spring is insufficient.
③
The timing between the needle and
hook is too early or too late.
④
The needle thread tension is
excessive.
⑤
The needle comes in contact with
the hook point.
⑥
The clearance between the needle
and the hook point is too large.
①
The thread has not been passed
through the notch of the bobbin case
tension spring.
②
The thread path is poorly finished.
③
The the bobbin does not rotaate is
too high.
④
The bobbin thread tension is too
high.
⑤
The bobbin thread tension is too
low.
⑥
An untwisted synthtic thread is
used.
⑦
Selection of needle size.
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