Table Of Troubles And Corrective Measures; With Reagard To Sewing - JUKI DNU-1541 Engineer's Manual

11. TABLE OF TROUBLES AND CORRECTIVE MEASURES

(1) With reagard to sewing

Troubles
Thread breakage
Thread is worn out.
Needle thread trails 2 to 3
cm from the wrong side of
the fabric.
Stitch skipping
Causes
Thread path, needle
point, hook blade point or
i n n e r h o o k r e s t i n g
groove on the throat
plate has sharp edges or
burrs.
Needle thread tension is
too high.
Needle comes in contact
with the blade point of
hook.
Needle thread tension is
too low.
Thread take-up spring
works excessively or the
stroke of the spring is too
small.
Feed timing is not proper.
Timing between the
needle and the hook is
excessively advanced or
retarded.
Thread melts due to
needle heat.
Clearance between the
needle and the blade
point of hook is too large.
Needle-to-hook timing is
excessively advanced or
retarded.
Height of the needle bar
is improper.
Presser foot is rising.
Blade point of the hook
is blunt.
Improper typr of needle
is used.
Thread take-up spring
excessively works or the
stroke of the spring is too
small.
Feed timing is not proper.
Checking
Check the sharp edge or
burr on the respective
parts.
Check the clearance.
Check the specified
dimension.
Check the clearance.
Check the specified
dimension.
Check the lowest point of
the needle bar.
Check the pressure of
the presser foot.
Check the blade point of
the hook.
49
Corrective measures
Remove the sharp edges or burrs
on the blade point of hook using
a fine emery paper. Buff up the
groove section on the throat plate.
Adjust the needle thread tension.
Refer to "(6) Needle-to-hook
timing"
Adjust the needle thread tension.
(This trouble occurs a lot when
using synthetic threads.
Decrease the tension of of the
t h r e a d t a k e - u p s p r i n g a n d
increase the stroke of the spring.
Refer to "(9) Feed cam timing".
Refer to "(6) Needle-to-hook
timing".
Decrease the sewing speed.
Use silicone oil.
(Refer to "(4) Others *".)
Refer to "(6) Needle-to-hook
timing".
Tighten the presser spring
regulator.
Correct the blade point of the hook
or replace the hook.
Replace the needle with one
which is thicker than the current
needle by one count.
Decrease the tension of the
t h r e a d t a k e - u p s p r i n g a n d
increase the stroke of the spring.
Refer to "(9) Feed cam timing".