Bad Sewing Condition & Its Cause And - Mitsubishi PLK-E0504 Technical Manual

9. BAD SEWING CONDITION & ITS CAUSE AND REMEDY
Please fix the troubles during the sewing machine operation with referring to the
NOTE
following instructions.
Beside, if the trouble conditions are not coming under these classification, please
contact the sewing machine dealers nearby.
Bad condition
Poor thread quality
Tight upper thread tension
Strong thread take up spring
Upper thread is thicker than
needle size
Damages on shuttle hook or
driver
1.
Damages inside needle plate
Upper thread
needle hole
breakage often
Damages inside presser foot
happens
needle hole
Needle touches with presser foot
needle hole
Needle and shuttle hook are not
in proper timing
Thread melts with needle heat
Thread tension discs are not
opened at trimming
Thread take up spring swings too
much
Upper thread is broken before
regular trimming
Needle size is bigger than thread
size
2.
Upper thread is
Pre-tension is too tight
pulled out from
Thread guide is in wrong position
needle
Needle and shuttle hook are in
bad timing
Trimmer timing is not correct
Cause
－ －
37
Remedy
Use better quality thread
Adjust thread tension
Adjust thread take up spring
properly
Change needle to suitable
size
Change them new ones or
grind them with buffing wheel
or grind stone
Change it new one or grind it
with buffing wheel
Change it new one or grind it
with buffing wheel
Move presser foot position
Adjust the timing
Slow down sewing speed
Use silicon oil
Use needle cooler
Adjust thread tension release
Adjust thread take up spring's
swing stroke
Adjust fixed knife and needle
plate position
Change needle to suitable
size
Adjust pre-tension
Adjust thread guide position
properly
Adjust the position properly
Adjust trimmer cam position
Adjust movable knife position
Adjust synchronizer position
Ref. page
& Item
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6-3
7-14
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6-2
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7-17
7-13
7-12
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7-15
7-5
7-2
7-10
7-11
7-18