
67
Thread Break
Before Trimming
by Moving Blade
Too Short Upper
Thread After
Trimming
①
Too short upper thread
■
Check the tension of the
main and auxiliary tension
adjusting device on the
thread tension adjusting
plate.
■
Scratch or damage to the
moving blade
②
Too short lower thread
■
The lower thread is not
smoothly released.
■
Too weak or too elastic
lower thread
①
Thread escape due to too
short upper thread after
trimming
②
Remaining upper thread on
the surface after trimming
due to too long upper thread
■
Adjust the upper thread
tension
■
Remove the scratch
(whetstone or sandpaper) or
replace the moving blade
■
Adjust or replace the
bobbin pressure spring of
the bobbin case
■
Clean the foreign materials
in the thread guide of the
bobbin case and check the
scratch
■
Replace the lower thread
■
Check the tension of the
upper thread
■
Set the remaining thread
length after trimming to be
[long] or [medium] in the
settings of the operational
panel
■
Set the remaining thread
length after trimming to be
[short] or [medium] in the
settings of the operational
panel
■
In the case where the head's
upper thread holder Velcro
is too narrow: Clean up the
inside of the Velcro
■
If the lower thread is
too short after
trimming, the initial
stitch is not formulated.
■
The remaining thread
length is set at
[medium] as default.
Corrective Action and Check Point
Cause of Trouble
Type
Remarks
Areas to check for scratch