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8. TROUBLES IN SEWING AND CORRECTIVE MEASURES
Troubles Causes Corrective measures
1. Thread breakage
(Thread frays or is
worn out.)
(Needle thread trails 2
to 3 cm from the wrong
side of the fabric.)
①
Thread path, needle point, hook blade
point or bobbin case resting groove on
the throat plate has sharp edges or burrs.
②
Needle thread tension is too high.
③
Bobbin case opening lever provides an
excessive clearance at the bobbin case.
④
Needle comes in contact with the blade
point of hook.
⑤
Amount of oil in the hook is too small.
⑥
Needle thread tension is too low.
⑦
Thread take-up spring works excessively
or the stroke of the spring is too small.
⑧
Timing between the needle and the hook
is excessively advanced or retarded.
○
Remove the sharp edges or burrs on the
blade point of hook using a ne emery paper.
Buff up the bobbin case resting groove on
the throat plate.
○
Decrease the needle thread tension.
○
Decrease the clearance provided between
the bobbin case opening lever and the
bobbin. Refer to
"4-7. Adjusting the bobbin
case opening lever" p.29
.
○
Refer to
"4-5. Needle-to-hook relation"
p.27
.
○
Adjust the amount of oil in the hook properly.
Refer to
"3-1. Lubrication" p.12
.
○
Increase the needle thread tension.
○
Decrease the tension of the spring and
increase the stroke of the spring.
○
Refer to
"4-5. Needle-to-hook relation"
p.27
.
2. Stitch skipping
①
Timing between the needle and the hook
is excessively advanced or retarded.
②
Pressure of the presser foot is too low.
③
The clearance provided between the top
end of the needle eyelet and the blade
point of hook is not correct.
④
Hook needle guard is not functional.
⑤
Improper type of needle is used.
○
Refer to
"4-5. Needle-to-hook relation"
p.27
.
○
Tighten the presser spring regulator.
○
Refer to
"4-5. Needle-to-hook relation"
p.27
.
○
Refer to
"4-6. Adjusting the hook needle
guard" p.28
.
○
Replace the needle with one which is thicker
than the current needle by one count.
3. Loose stitches
①
Bobbin thread does not pass through the
tension spring of the inner hook.
②
The hook, feed dog or the thread path
of thread guide, etc. has worn out or has
aws.
③
Bobbin fails to move smoothly.
④
Bobbin case opening lever provides too
much clearance at the bobbin.
⑤
Bobbin thread tension is too low.
⑥
Bobbin has been wound too tightly.
⑦
The needle does not match the needle
hole in the feed dog.
○
Thread the bobbin thread correctly.
○
Remove rough parts with a ne emery paper
or buff it up.
○
Replace the bobbin or hook with a new one.
○
Refer to
"4-7. Adjusting the bobbin case
opening lever" p.29
.
○
Increase the bobbin thread tension.
○
Decrease the tension applied to the bobbin
winder.
○
Change the feed dog appropriately. (Refer to
the Parts List.)
4. Thread slips off
the needle eyelet
simultaneously with
thread trimming.
①
Thread tension given by the tension
controller No. 1 is too high.
○
Decrease the thread tension given by the
tension controller No. 1.
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