Troubles In Sewing And Corrective Measures - JUKI DNU-1541-7 Instruction Manual

25.
TROUBLES IN SEWING AND CORRECTIVE MEASURES
Troubles
Causes
Corrective measures
1 • Thread breakage
Q) Thread path, needle point, hook
o Remove the sharp edges or burrs on
(Thread frays or IS worn
blade point or bobbin case resting
the blade point of hook using a fine
out)
groove on the throat plate has sharp
emery paper Buff up the bobbin case
edges or burrs.
restmg groove on the throat plate.
.t
Needle thread tension is too high.
o Decrease the needle thread tension .
J) Needle comes in contact with the
o Refer to "18. NEEDLE-TO-HOOK
blade point of hook.
RELATION".
I! Amount of oil in the hook is too small.
o AdJUSt the amount of oil in the hook
properly.
Refer to "6 LUBRICATION"
(Needle thread tra1ls 2 to
W
Needle thread tension 1s too low.
" Increase the needle thread tension.
3 em from the wrong side
6
Thread take-up spring works
o Decrease the tension of the spring and
of the fabric.)
excessively or the stroke of the
increase the stroke of the spring.
spring is too small.
(V liming between the needle and the
o Refer to
"18.
NEEDLE-TO-HOOK
hook 1s excessively advanced or
RELATION".
retarded.
f -
2. Slltch sk1pping
(f liming between the needle and the o Refer to "18. NEEDLE-TO-HOOK
hook is excessively advanced or
RELATION".
retarded.
j
®
Pressure of the presser foot is too low. o lighten the presser spring regulator.
3
The clearance provided between the
o Refer to
"18.
NEEDLE-TO-HOOK
top end of the needle eyelet and the RELATION".
blade point of hook is not correct.
@ Hook needle guard is not functional. o Refer to
"18.
NEEDLE-TO-HOOK
RELATION".
ID
Improper type of needle is used. o Replace the needle with one which is
thicker than the current needle by one
count
3 . Loose slltches
<b
The bobbin thread has not been
.
,.... See
"8.
THREADING THE BOBBIN
passed through the bobbm case CASE"
tension spring
'2)
Thread path has been poorly o Remove rough parts with a fine emery
fmished.
paper or buff it up.
1) Bobbin fa1ls to move smoothly. o Replace the bobbin or hook with a new
one
(! Bobbin thread tension is too low. o Increase the bobbin thread tension.
~
Bobbin has been wound too tightly.
o Decrease the tension applied to the
bobbin winder.
--
®
The needle tip is blunt
o Replace the needle.
4. Thread shps off the needle <D
Thread tension given by the tension o Decrease the thread tension given by
eyelet Simultaneously with
controller No. 1 is too high.
the tension controller No. 1.
thread tnmming.
:1) A hard-to-slip thread 1s used.
o Decrease the number of t1mes of
threading the needle thread.
5 Thread shps off the
(i) Thread tens1on given by
th~
tension
o Decrease the thread tension given by
needle eyelet at the start
controller No. 1 is too h1gh.
the tension controller No. 1.
of sewing
®
Bobb1n thread tension is too low.
o Increase the bobbin thread tension.
6. Thread is not cut sharply.
(!)
The thread trimming timing is wrong.
o See
"19.
ADJUSTING THE THREAD
®
The knives have blunt blades.
TRIMMING".
o Replace the rotary knife and counter
kmfe with new ones, or correct the
J) The kn1fe pressure is too low.
current ones.
o See "19. ADJUSTING THE THREAD
7. Thread remains uncut
TRIMMING".
-
Q) }he position of the rotary knife is
o See "19. ADJUSTING THE THREAD
after thread tnmm1ng.
maccurate
TRIMMING".
' 2)
The thread trimming timing is wrong.
,.... See "19 ADJUSTING THE THREAD
B.
St1tch skipping occurs at
TRIMMING".
-
1
The length of remaining bobbin
o Decrease the bobbin thread tension
the start of sew1ng after
thread is too short.
thread trimming
I - - •
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46