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11. TABLE OF TROUBLES AND CORRECTIVE MEASURES
(1) With reagard to sewing
Thread breakage
Thread is worn out.
Needle thread trails 2 to 3
cm from the wrong side of
the fabric.
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.
Clearance of inner hook
guide is too large.
Amount of oil in the hook
is insufficient.
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.
T i m i n g b e t w e e n t h e
needle and the hook is
excessively advanced or
retarded.
Thread melts due to
needle heat.
Amount of oil in the hook
is excessive.
Check the sharp edge or
burr on the respective
parts.
Check the clearance.
Check the clearance.
Check the amount of oil
in the hook.
Check the specified
dimension.
Check the amount of oil
in the hook.
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 "(17) Lubrication".
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 “(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 “(17) Lubrication”.
Troubles
Causes
Checking
Corrective measures
1
* Use separately available parts below : “21144308 Needle thread lubricator”
“B1114012000 Thread guide rod”
“B91351230B0 Silicon oiler”
