JUKI MEB-3810N Series Instruction Manual page 103

Phenomenon
6. L o o p e r t h r e a d • The looper thread tension is too high.
breakage
• The installing position of the left-hand
is incorrect.
• Refer to "5. Needle thread breakage" for details on
other causes and corrective measures
7. Needle breakage • The needle interferes with looper, spreader, etc.
• The needle comes in contact with the presser foot.
• The clearance between the needle and the looper
varies according to the turning angle (0˚, 90˚ and
180˚).
• The clearance between the needle and the needle
guard is too large or the needle and the needle
guard come in excessive contact with each other.
• The height of the needle bar has been improperly
adjusted.
• The needle thread • Needle thread is depressed by the presser foot at
clamp unit is not the start of sewing.
installed.
8. S t i t c h e s a t t h e • The left- and right-hand sewing pitches at the
straight section of straight section are different from each other.
the buttonhole are • The left- and right-hand positions at the straight
not uniform. section are different from each other.
• Stitches which should be parallel are slant.
9. The left- and right- • The left- and right-hand side cloth opening
hand sides of the amounts are not equal.
seam at the straight • Improper adjustment of the knife dropping position
section of the but- • There is shrinkage of cloth by sewing or step
tonhole are not uni- difference between left- and right-hand sides of
form. cloth.
10. The shape of the • The seam is tilted.
eyelet is deformed.
• The cloth is deformed by the seam.
• Improper adjustment of the knife dropping position
• The cloth at eyelet section is flopping.
• The gimp is moved to the inside needle side.
11. The seam is cut by • The clearance between the cloth cutting knife and
the cut-after knife. the needle is too small.
• Improper adjustment of the knife dropping position
• There is shrinkage of cloth by sewing or step
difference between left- and right-hand sides of
cloth.
12. Needle thread can- • The needle thread trimming knife is dull.
not be trimmed. • The stroke of the needle thread trimming knife is
incorrect.
• The needle thread trimming knife does not catch
needle thread.
• The last stitch has skipped.
• Installing position of the moving blade is incorrect.
13. Looper thread can- • The knife is dull.
not be trimmed. • The knife position is wrong.
14. The cloth cannot be • Doubling the planes of the knife and the hammer
cut sharply. is incorrect.
• The knife is dull.
• The knife pressure is inadequate.
• Chip has collected.
• Knife pressure is too high and the knife blade has
broken.
15. Breakage of looper/ • The clearance between the needle and the looper
spreader varies according to the angle (0˚, 90˚ and 180˚).
• The clearance between the needle and the needle
guard is too large or the needle and the needle
guard come in excessive contact with each other.
Cause
• Adjust the sewing conditions to obtain an appropri-
spreader • Check and adjust the installing position.
• Adjust the clearance between the looper and the
• Check and adjust the clearance.
• Adjust the center of the needle.
• Check and adjust the clearance.
• Check and adjust the height of the needle bar.
• Properly adjust the needle thread drawing amount.
• Compensate the length by lengthwise compensa-
• Compensate the position by lengthwise compen-
• Compensate the inclination by turning compensa-
• Adjust so that the left- and right-hand side cloth
• Check and adjust the knife dropping position.
• Individually set the left- and right-hand sides of cut
• Set the turning compensation/parallel section turn-
• Set the eyelet crosswise compensation/lengthwise
• Check and adjust the knife dropping position.
• Adjust the position of the presser foot.
• Replace the throat plate with the optional one.
• Check the cut (eyelet) space and re-set it.
• Check and adjust the knife dropping position.
• Individually set the left- and right-hand sides of cut
• Grind the knife or replace it with a new one.
• Check and adjust the stroke.
• Adjust the installing position (clearance between
• Refer to "1. Stitch skipping".
• Check and adjust the moving blade and the thread
• Grind the knife or replace it with a new one.
• Properly adjust the knife position.
• Correct the surface of the hammer with oil stone or
• Grind the knife or replace it with a new one.
• Re-set the knife pressure.
• Remove the chip.
• Set proper knife pressure to each sewing product
• Adjust the center of the needle.
• Check and adjust the clearance.
– 100 –
Corrective measure
ate thread tension.
needle properly. Adjust the timing to open/close the
spreaders properly.
tion of left parallel section of the data compensation.
sation of left eyelet of the data compensation.
tion of parallel section of the data compensation.
opening amounts are equal.
space.
ing compensation.
compensation.
space.
needle and knife) of the knife.
separating position.
the like.
after replacing the knife.
Page
44, 73
85
84 to 86
68, 88
-
84
82
69
57
57
55
68
88
54, 57
55
56
88
88
96
52,
54 to 57
88
54, 57
73, 89, 94
89
89
-
89
93
79
91
92
65
92
65, 92
-
84