Troubles And Corrective Measures (Sewing Conditions) - JUKI AB-1351 Instruction Manual

1-17. troubles and corrective measures (sewing conditions)

trouble
1. The needle 1 Sttches are slpped at the start.
thread slps
off at the
start of bar-
tackng. 2 The needle thread remanng on the
needle after thread trmmng s too
short.
3 The bobbn thread s too short.
4 Needle thread tenson at 1st sttch s
too hgh.
5 Thread clamp s unstable (materal s
apt to be expanded, thread s hard to
slde, thread s thck, etc.).
6 Thread clamp s unstable (materal s
apt to be expanded, thread s hard to
slde, thread s thck, etc.).
2. Thread 1 The shuttle or the drver has
often scratches.
breaks or 2 The needle hole gude has scratches.
synthetc 3 The needle strkes the work clamp
fiber thread foot.
splits finely. 4 Fbrous dust s n the groove of the
shuttle race.
5 The needle thread tenson s too hgh.
6 The tenson of the thread take-up
sprng s too hgh.
7 The synthetic fiber thread melts due to
heat generated on the needle.
3. The needle 1 The needle s bent.
often 2 The needle hts the work clamp foot.
breaks. 3 The needle s too thn for the materal.
4 The drver excessvely bends the
needle.
5 Needle thread s stepped on by the
work clamp foot at the start of sewng.
(Needle bend)
4. Threads 1 The counter knfe s dull.
are not 2 The dfference n level between the
trmmed. needle hole gude and the counter
knfe s not enough.
3 The movng knfe has been mproperly
postoned.
4 The last sttch s skpped.
(Bobbn thread
only) 5 Bobbn thread tenson s too low.
5. Sttch 1 The motons of the needle and shuttle
skppng are not properly synchronzed.
often 2 The clearance between the needle
occurs. and shuttle s too large.
3 The needle s bent.
4 The drver excessvely bends the needle.
cause
– 142 –
corrective measures
™ Adjust the clearance between the needle
and the shuttle to 0.05 to 0.1 mm.
™ Set the sewng machne so that the sewng
speed s lowered at the begnnng of sewng.
™ Correct the thread tenson release tmng of
the thread tenson controller No. 2.
™ Increase the tenson of the thread take-
up sprng, or decrease the tenson of the
thread tenson controller No. 1.
™ Decrease the tenson of the bobbn thread.
™ Increase the clearance between the needle
hole gude and the counter knfe.
™ Decrease the tenson at 1st sttch.
™ Decrease the number of rotaton at 1st
sttch at the sewng start. (Extent of 600 to
1,000 st/mn)
™ Increase the number of sttches of thread
clamp to 3 to 4 sttches.
™ Make the ptch at 1st sttch longer.
™ Decrease the needle thread tenson at 1st
sttch.
™ Take t out and remove the scratches usng
a fine whetstone or buff.
™ Buff or replace t.
™ Correct the poston of the work clamp foot.
™ Take out the shuttle and remove the fibrous
dust from the shuttle race.
™ Reduce the needle thread tenson.
™ Reduce the tenson.
™ Use slcone ol.
™ Replace the bent needle.
™ Correct the poston of the work clamp foot.
™ Replace t wth a thcker needle accordng
to the materal.
™ Correctly poston the needle and the
shuttle.
™ Wden the dstance between the needle
and the wper. (16 to 18 mm)
™ Replace the counter knfe.
™ Increase the bend of the counter knfe.
™ Correct the poston of the movng knfe.
™ Correct the tmng between the needle and
the shuttle.
™ Increase the bobbn thread tenson.
™ Correct the postons of the needle and
shuttle.
™ Correct the postons of the needle and
shuttle.
™ Replace the bent needle.
™ Correctly poston the drver.
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