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4. The needle thread slips off the needle
4-1) The length of the needle thread
1-A) Too high 1st thread tension due
Turn off the power, push the hook thread presser into the
at the sewing start.
passing through the needle varies
to delayed thread trimming timing
bobbin case by hand when the needle reaches the lowest
after thread trimming.
causes the thread to be cut
point, trim the needle while turning the hand wheel, and
before engagement between
stop the hand wheel when the thread take-up lever comes
the moving and counter knives.
to the upper dead point.
(midway cut)
If the length of the needle thread passing through the needle
at this moment is 10 mm or more shorter than that of the
pedal operation, hasten the timing of thread trimming or
decrease the 1st thread tension because this is a midway cut.
4-2) The cause and measures are the
2-A) Shallow entry of the hook thread
Adjust the hook thread presser with reference to 3. -(11)-9).
same as those for the item, "1.
presser into the bobbin case
Skipping of one or more stitches
occasionally causes the needle
occurs at the start of sewing".
thread to be unfastened from
the hook thread presser.
2-B) Sharpening the counter knife is
Resharpen or replace the counter knife with reference to
inappropriate. (too sharpened)
3.-11)-6).
2-C) The knife thread guide, moving
Buff the flaw portion or replace the damaged component.
knife, or hook has a flaw
2-D) The needle is too thick.
Replace the needle with a thinner one.
4-3) The needle thread slips off the
3-A) Too early cam timing or too late
Slipping of the needle thread from the needle immediately
needle immediately after thread
hook timing causes the moving
after thread trimming results from cutting the needle thread
trimming.
knife to cut the needle thread to
passing though the needle due to defective thread spread-
hold 3 threads before thread
ing by the moving knife. In such a case, Thread chips of
separation.
40mm level exist under the throat plate or on the under cover.
In this case, delay the timing of the thread trimming cam.
4-4) Knot tying between the needle
4-A) The sewing speed at sewing
Conduct 1 or 2 stitches of soft-start at the sewing start.
and bobbin threads is not easy
start is too fast to knot the needle
at sewing start.
and bobbin threads together.
4-5) Improper clearance of picker
5-A) The picker is too strongly functioning
Adjust the picker alignment to a weaker level.
and it disturbs idling that is needed
for the bobbin.
5. The thread tension is inappropriate at
5-1) The tension of the needle thread
1-A) The hook thread presser is
Adjust the hook thread presser with reference to 3.-(11) -9).
sewing start.
is too low at sewing start.
inappropriately mounted.
1-B) Bobbin idling causes the bobbin
Adjust the hook thread presser with reference to 3.-(11) -9).
thread tension at sewing start to
decrease.
Adjust the tension of the idling prevention spring of the bobbin case.
1-C) The tensions of the bobbin thread
Increase the tensions of the bobbin thread and needle
and needle thread are too low.
thread.
1-D) The presser or throat plate is
Refer to the previous item, [An inappropriate needle, throat plate, or
inappropriate.
presser is used. Alternatively, he pressure of the presser is too low].
Trouble
Case (1)
Case (2)
Check and Corrective measures
Summary of Contents for DDL-9000A
Page 14: ... 10 4 Feed locus and phase 1 Timing standard 2 Timing fast 3 Timing slow Standard Adjustment ...
Page 32: ... 28 8 Adjustment of the amount of feeding 4 Optional switch Standard Adjustment ...
Page 60: ... 56 11 Thread trimming unit 7 Replacement of the moving knife Standard Adjustment ...
Page 66: ... 62 11 Thread trimming unit 10 Adjustment of the drive arm stopper Standard Adjustment ...
Page 70: ... 66 12 Adjustment of the wiper DDL 9000A WB OB 2mm 1mm Standard Adjustment ...
Page 72: ... 68 13 Adjustment of feed lever pressure B A Feed lever Standard Adjustment ...
Page 112: ...MEMO ...
