– 54 –
2. Thread cut at bobbin 2-1)Thread path 1-A)Resistance is developed Take measures to remove flaws, burrs, etc., and
thread looper when there is a scratch, finish the thread path neatly.
a burr, or rust on the In this case, however, the throt plate, lower
throat plate, lower looper, looper, bobbin thread cam, and such impor-
bobbin thread cam, tant parts should be replaced if their shapes
bobbin thread path pipe, seem to have changed.
bobbin thread path guide,
or thead tension disc.
2-2)Adjustment of bobbin 2-A)Excessive tension is Refer to the standard adjustment values.
thread cam provided because of
improper timing of the
bobbin thread cam.
2-3)Thread tension 3-A)Excessive thread tension Reduce the tension in consideration of the
tension balance with the needle thread.
2-4)Thread 4-A)Poor quality of the thread Use a high-quality thread.
2-5)Needle heat 5-A)Thread cut occurs when Reduce the sewing speed.
the thread touches the
right needle at sewing
stop due to needle heat.
3. Needle breakage 3-1)Needle entry 1-A)Front/rear and right/left Refer to the standard adjustment values.
needle entry seems to
be awkward in conjunction
with the needle hole of
the throat plate.
3-2)Interference between 2-A)
The needle breaks because
Adjust the lower looper to prevent the
lower looper and blin
of the interference between
nterference.
dstitch of needle the tip of the lower looper Refer to the standard adjustment values.
and the needle.
3-3)Interference between 3-A)
The needle breaks because
(6) Adjust the looper movement locus.
rear of lower looper of the strong interference Refer to the standard adjustment values.
and needle tip between the rear of the
lower looper and the
needle tip.
3-4)Rear needle guide 4-A)Excessive clearance Adjust the clearance between the needle and
between the needle and rear needle guide.
rear needle guide causes
Refer to the standard adjustment values.
needle shaking and then
interference between the
needle and the lower
looper tip resulting in
needle breakage.
3-5)Needle size 5-A)For the case that the Use a thicker needle.
needle is too thin for the
material that is now used
3-6)Thread tension 6-A)Excessive needle thread Reduce the needle thread tension.
tension
3-7)Feed dog height 7-A)Too high feed tooth Refer to the standard adjustment values.
causes needle sidewise
movement resulting in
needle breakage.
4. Needle edge blunting 4-1) Needle entry 1-A)Front/rear and right/left Refer to the standard adjustment values.
needle entry seems to
be awkward in conjunction
with the needle hole of
the throat plate.
4-2)Rear needle guide 2-A)Improper position of the Clearance check between rear needle guide
front-to-rear direction and needle
Refer to the standard adjustment values.
4-3)Contact with the rear 3-A)
Too often contact between
(6) Adjust the looper movement locus to make
of the looper the rear of the lower the contact level appropriate when the lower
looper and the needle tip looper moves backward.
Refer to the standard adjustment values.
Trouble Cause (1) Cause (2) Check and corrective measures
To Next Page
Loading...
