60
PROBLEM TIP or PAGEREMEDYPROBABLE CAUSE
Frequent thread
breaks.
Choose quality thread and
store it away from sunlight
and dust.
Z-twisted thread(twisted to
the left)
S-twisted thread(twisted to
the right)
Z-twist prevents unraveling
of thread in the
counterclockwise rotation
of the hook
Check rotary hook.
Use good quality thread.
Use Z-twisted thread.
The rotary hook rotates
counterclockwise so Z-
twisted thread prevents the
upper thread from
unraveling.
Adjust tension.
Adjust tension.
Adjust spring tension and
take-up lever.
Use crocus cloth to remove
any nicks and scratches or
replace the damaged part(s).
Adjust the distance.
Poor quality or old thread
(uneven poorly twisted, or
poorly wound.)
Using S-twisted thread.
Upper thread tension is too
tight.
Upper and lower thread not
adjusted correctly in
relationship to each other.
Spring tension is too tight or
take-up lever is not adjusted
correctly.
Damaged hook or bobbin
case.
Distance between the hook
and the groove of the
needles is too narrow.
* Correct distance for smooth
passing of upper thread is
0.5~0.7mm.
0.5~0.7mm
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