Table Of Troubles And Corrective Measures; With Regard To Sewing - JUKI LU-1510N-7 Engineer's Manual

9. TABLE OF TROUBLES AND CORRECTIVE MEASURES

(1) With regard to sewing

Troubles
Thread breakage
1
Thread is worn out.
Needle thread trails 2
to 3 cm from the wrong
side of the fabric.
* Use separately available parts below : "21144308 Needle thread lubricator"
Causes
Thread path, needle point,
hook blade point or inner
hook resting 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.
Clearance of inner hook
guide is too large.
Amount of oil in the hook
is insufficient.
Trimmed with the tooth
of the feed dog.
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.
Amount of oil in the hook
is excessive.
"B1114012000 Thread guide rod"
"B91351230B0 Silicon oiler"
Checking
Check the sharp
edge or burr on the
respective parts.
Check the clearance.
Check the clearance.
Check the amount of
oil in the hook.
Feed dog check
Alternate vertical
movement check
Sewing speed check
Check the specified
dimension.
Check the amount of
oil in the hook.
– 67 –
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 "(7) Needle-to-hook
timing"
Decrease the clearance. Refer to
"(6) Adjusting the inner hook
guide".
Adjust the amount of oil in the
hook. Refer to "(21) Lubrication".
Provide a groove behind the
feed dog needle hole
Reduce the amount of alternate
vertical movement.
Reduce the sewing speed.
Adjust the needle thread tension.
(This trouble occurs a lot when
using synthetic threads.
Decrease the tension of of the
thread take-up spring and
increase the stroke of the spring.
Refer to "(9) Feed cam timing".
Refer to "(7) Needle-to-hook
timing".
Decrease the sewing speed.
Use silicon oil. (Refer to * below.)
Adjust the amount of oil in the
hook. Refer to "(21) Lubrication".