JUKI DLN-6390 Manuel D'utilisation page 98

Troubles Causes (Items to be checked)
Needle breakage Check whether cloth is properly rolled.
Check whether relation of position between
needle and needle hole is proper.
Check whether the position of the hemming
binder is proper.
Stitch skipping
Check whether clearance between needle
and blade point of hook is proper.
Check whether blade point of hook has a
scratch or is blunt.
Check whether thread tension is too high.
Check whether the position of the hemming
binder is proper.
(Check whether the hemming binder
interferes with the presser foot (asm.).)
Check whether clearance between needle
Thread breakage
and blade point of hook is proper.
Check whether blade point of hook has a
scratch or is blunt.
Check whether thread tension is too high.
Check whether the position of the hemming
binder is proper.
(Check whether the hemming binder
interferes with the presser foot (asm.).)
Check whether needle attaching is proper.
(Direction, insuffi cient insertion, etc.)
Check whether the tension of thread tension
No. 1 is low. (In case of thread trimmer)
Check whether quality of thread is not good.
Check whether thread is cut from heat.
Looping
Check whether kind or size of needle is proper.
(balloon stitch)
Check whether relation of position between
needle and needle hole is proper.
Check whether needle cooler air pressure is
too high.
Check whether thread tension is too low.
Check whether the tension of thread take-up
spring is low or the stroke is small.
Check whether the tension of thread is proper.
Corrective measures
Adjust by handling so that hemming of the bottom
can be properly performed.
(Feed force is not stabilized when cloth becomes
thick due to the failure of rolling.)
Adjust the position of throat plate and presser foot
(asm.) to a proper one.
(The proper position of needle in terms of needle
hole in the throat plate is in the center of both sides
and that in terms of needle hole in the presser foot
(asm.) is slightly to the right side.)
Adjust the position to a proper one.
(Needle is apt to break when needle pierces the
limit of edge of the fold.)
Make the clearance between needle and blade point
of hook come near to "0" when thread is caught.
Remove the scratch or replace the hook with a new
one.
Decrease the thread tension.
Adjust the position to a proper one.
(When the hemming binder interferes with the
presser foot (asm.), the presser foot (asm.) rises
from the throat plate, or the motion is limited.)
Make the clearance between needle and blade point
of hook come near to "0" when thread is caught.
Remove the scratch or replace the hook with a new
one.
Decrease the thread tension.
Adjust the position to a proper one.
(When the hemming binder interferes with the
presser foot (asm.), the presser foot (asm.) rises
from the throat plate, or the motion is limited.)
Properly attach the needle.
A d j u s t t h e t e n s i o n t o s u c h a n e x t e n t t h a t
unsteadiness of thread does not occur.
Use a good quality thread.
Increase the amount of oil in the hook.
Replace the needle with a proper one.
SCHMETZ UY180GVS is recommended.
(Sewing performance is stabilized when using a
thick one if possible.)
Adjust the position of throat plate and presser foot
(asm.) to a proper one.
(The proper position of needle in terms of needle
hole in the throat plate is in the center of both sides
and that in terms of needle hole in the presser foot
(asm.) is slightly to the right side.)
Set the air pressure to a proper one (it is better to
set it to rather low).
Increase the thread tension.
Adjust the tension or the stroke to a proper value.
(0.2N and 8 mm are recommended.)
Re-adjust the tension of thread to a proper one.
(If the thread tension is too low, needle thread is
not fully drawn up, and if it is too high, the twist is
tightened and looping is apt to occur.)
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