Bad Sewing Condition & Its Cause And Remedy - Mitsubishi PLK-E2010R Instruction Manual

9. BAD SEWING CONDITION & ITS CAUSE AND REMEDY
NOTE Please fix the troubles during the sewing machine operation with referring to the 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 rotating hook
1.
Damages inside needle plate needle
Upper thread
hole
breakage often
happens
Damages inside presser foot needle
hole
Needle touches with presser foot
needle hole
Needle and rotating 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
Needle size is bigger than thread size Change needle to suitable size
2.
Pre-tension is too tight
Upper thread is
Thread guide is in wrong position
pulled out from
needle
Needle and rotating hook are in bad
timing
Trimmer timing is not correct
Too short bobbin thread by bobbin
spinning at trimming
Bobbin thread tension is too tight
Thread tail from needle is very short
after trimming
3.
Skip stitch
happens at start
sewing
Cause
- 44 -
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 pre-tension
Adjust thread guide position
properly
Adjust the position properly
Adjust trimmer cam position
Adjust movable knife position
Adjust synchronizer position
Use non racing spring with bobbin
Loosen bobbin thread tension
spring
Decrease pre-tension
Adjust trimmer cam position
Adjust synchronizer position
Make thread take up swing stroke
smaller
Advance thread tension release
timing
Adjust thread guide position
properly
Adjust the position properly
Ref. page &
Item
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P19-6-3-2)
P36-7-14
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---
---
---
---
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P18-4)
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P35-7-10
P36-7-13
---
P36-7-11
P35-4)
P21-7-2
P32-7-9-2.6
P34-7-9-2.7
P37-7-15
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P19-6-3-1)
P36-7-11
P32-7-9-2.6
P37-7-15
P36-7-13
Control unit
P35-4)
P21-7-2