– 114 –
Trouble
Cause
Corrective measures
Page
5. Stitch skipping
often occurs.
①
The motions of the needle and
shuttle are not properly synchro-
nized.
◦
Correct the positions of the needle and
shuttle.
103
②
The clearance between the needle
and shuttle is too large.
◦
Correct the positions of the needle and
shuttle.
103
③
The needle is bent.
◦
Replace the bent needle.
9
④
The driver excessively bends the
needle.
◦
Correctly position the driver.
103
6. The needle
thread comes
out on the wrong
side of the mate-
rial.
①
The needle thread tension is not
high enough.
◦
Increase the needle thread tension.
11
②
The tension release mechanism
fails to work properly.
◦
Check whether or not the tension disc
No. 2 is released during bar-tracking.
③
The needle thread after thread
trimming is too long.
◦
Increase the tension of the thread ten-
sion controller No. 1.
◦
Correct the position of the moving knife.
11
④
Number of stitches is too few.
◦
Turn OFF the thread clamp.
⑤
When sewing length is short (End
of needle thread protrudes on the
wrong side of sewing product.)
◦
Turn OFF the thread clamp.
⑥
Number of stitches is too few.
◦
Use the lower plate, the hole of which
is larger than the presser.
7. Thread end of
the 1st stitch
comes out on
the right side of
the material.
①
Stitch skipping at the 1st stitch
◦
Adjust the hook timing faster by a 1/2
stitch.
②
Needle used and thread used are
thick in terms of the inner diame-
ter of the intermediate presser.
◦
Increase the inner diameter of interme-
diate presser.
③
Intermediate presser is not prop-
erly positioned in terms of the
needle.
◦
Adjust the eccentricity between inter-
mediate presser and needle so that
needle enters in the center of interme-
diate presser.
8. Threads break
at time of thread
trimming.
①
The moving knife has been im-
properly position.
◦
Correct the position of the moving
knife.
106
9. The thread clamp
is entangled with
needle thread.
①
The needle thread at the sewing
start is too long.
◦
Tighten thread tension controller No. 1
and make the length of needle thread
40 to 50 mm.
14
10. Uneven length of
the needle thread
①
The tension of thread take-up
spring is too low.
◦
Increase the tension of the thread take-
up spring.
12
11. The length of
needle thread
does not be-
come short.
①
The tension of thread tension
controller No. 1 is too low.
◦
Increase the tension of thread tension
controller No. 1.
11
②
The tension of thread take-up
spring is too high.
◦
Decrease the tension of thread take-up
spring.
12
③
The tension of thread take-up
spring is too low and motion is
unstable.
◦
Increase the tension of thread take-up
spring and lengthen the stroke as well.
12. The knotting
section of
bobbin thread
at 2nd stitch at
the sewing start
appears on the
right side.
①
Idling of bobbin is large.
◦
A just the position of the moving knife.
106
②
The bobbin thread tension is too
low.
◦
Increase the bobbin thread tension.
11
③
The needle thread tension at 1st
stitch is too high.
◦
Decrease the needle thread tension at
1st stitch.
◦
Turn OFF the thread clamp.
13. Wiper fails to
work. (Return is
defective.)
①
Needle entry of the last needle
is the same as that of the sewing
start, and the resistance of thread
and cloth is large.
◦
Shift the needle entry point of the last
needle.
14. Short thread
trimming of
needle thread
at the time of
thread trimming
①
Flopping of cloth
②
The last stitch pitch is excessively
small.
③
Thread trimming speed is
excessively fast.
◦
Lower the intermediate presser height
of the last stitch.
◦
Decrease the stroke of the intermediate
presser.
◦
Increase the last stitch pitch.
◦
Decrease the thread trimming speed.
106
