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Bird's nest prevention (CB) type
Phenomenon
Needle
1 Improper wiper position.
thread
clamp
2 Air pressure drop.
failure
3 Dust bag becomes excessively filled with
waste thread.
4 Thread trimmer or wiper operates when
needle does not enter the cloth.
5 Needle thread length is too short.
Thread does not reach the clamp head.
6 Uneven length of left and right needle threads
(Thread which is not stretched such as cotton
thread or the like is used.)
Bobbin
Bobbin thread is taken up on the cloth by needle
thread at
thread at 1st stitch at the start of sewing since
the start of
needle thread remaining amount after completion
sewing is
of needle thread clamp is small.
drawn up
on the
cloth.
Knife to cut
1 Worn-out of needle thread cutting knife.
needle thread
is dull.
2 Improper installing position of the knife.
3 Thick thread is used.
4 Start of sewing is set to the reverse feed.
Interference
1 Improper UP stop position.
of wiper
2 Improper wiper locus.
with needle
3 Improper wiper position.
4 Length of needle tip is longer than that of the
standard delivery needle.
Needle thread
1 Needle thread enters the needle thread cutting
is cut during
groove of the presser.
sewing.
144
Cause
Corrective measure
Adjust the wiper to the proper position.
Set the air pressure to 0.6Mpa.
Remove waste thread from the dust bag.
Operate thread trimmer or wiper on the cloth.
Perform pre-tension adjustment and lengthen
needle thread. (Adjust the length from the
clamp head to approximately 20 to 35 mm.)
Needle thread
Change the kind of thread.
Step 1 :
Increase the drawing amount of needle thread
and increase needle thread remaining amount
at the start of sewing.
Step 2 :
Make tension release SOL (solenoid) actuate
at the start of sewing to perform tension release
and increase the thread remaining amount.
(Input the number of stitches of thread release at
the start of sewing with function setting No.100.)
Step 3 :
Make the thread drawing device actuate again
after completion of needle thread clamp to
perform tension release and increase the
thread remaining amount.
(Set function setting No.18 to 2.)
Step 4 :
Make all step items (1 2 3) function.
Replace the knife with a new one.
Adjust the position to the proper one.
Change the thread count.
Change to the normal feed.
Adjust the UP stop position.
Re-adjust the locus of the wiper.
Re-adjust the position of the wiper.
Re-adjust the position of the wiper.
Replace the presser with the general presser
(presser without knife).
See page
131
16
134
132
120
Clamp head
130
113
110
110, 113
132
132
131
131
129
131
131
131
131
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