Troubles
Causes
Corrective
measures
Page
9)
Bobbin
thread
tension
is
not
stable
while it is being
pulled
o
Replace
the
bobbin
or
bobbin
out.
case.
10)
Bobbin
fails to
smoothly
o Replace it
with
an
aluminium
spin in
the
bobbin
case.
bobbin.
7. Puckering
1)
Needle
thread
tension
is
too
o
Reduce
the
needle
thread
16
high.
tension.
2) Tliread
paths
on the sewing
o
Polish
the
surface
of
such
hook,
throat
plate,
tension
thread
paths.
discs or
thread
take up lever
does
not
have
a
smooth
surface.
3) Feed timing is
too
early.
o Adjust the feed timing to
the
20
standard
or
a
little
later
than
the
standard.
4) Inclination
of
the feed dog
o Raise up the
front
part
of
the
21
is
not
proper.
feed dog
(front-up
position).
5) Position
of
the
feed dog is o Correct the feed dog height.
21
too
high.
6)
Needle
is
too
thick.
0
Replace
it
with
a
thinner
17
needle.
7) Bobbin
does
not
spin in
the
o
Replace
it
with
an
aluminium
bobbin
case.
bobbin.
8)
Needle
slot
in
the
throat
o Use a
throat
plate
which has
plate
is
too
great.
a
small
needle
slot.
9) Tension of the thread take-up o
Reduce
the
tension
of
the
16
spring is
too
high.
thread take-up spring.
8. Slipping
1) Presser foot does
not
give a o Increase the pressure
of
the
18
of
cloths.
sufficient pressure to the
presser
bar.
cloths.
2) Inclination
of
the feed dog is
o Raise up the
front
part
of
the
21
not
suitable.
feed dog (front-up position).
3) Feed timing is too late. o Make the feed timing earlier.
20
4)
Failure
in
material
feed.
o Use a feed dog with the course
teeth.
o Use a feed dog with the up
right
teeth.
o Use a feed dog
with
the
teeth
of
a sharper pressure angle.
9. Irregular
1) Sewing speed is too high.
o Reduce the sewing speed.
2
stitches
2)
Needle
thread
tension
is
too
o
Reduce
the
needle
thread
16
(as sewing
high.
tension
in
relation
with
the
speed
bobbin
thread
tension.
changes)
3)
Bobbin
thread
tension
is
too
o
Increase
the
bobbin
thread
17
low.
tension
in
relation
with
the
needle
thread.
4) Thread path on the sewing
o Polish such
thread
paths
by
hook,
throat
plate,
tension
using an
oilstone
or
buff.
discs,
thread
take-up lever
and
other
components
does
not
have
a
smooth
surface.
33
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