JUKI MO-6700D Series Manual page 54

Trouble
From the previous page
4. The needle point is crushed.
(Double chain stitch needle)
5. Overlocking needle thread stitches
are skipped.
The lower looper fails to catch
needle thread loops.
Right side Wrong side
to the next page
Case (1)
Needle guards
Needle No.
Thread tension
Height of the feed dog or needle
Needle guard
Contact with the looper
Lower looper
Adjustment of the loopers.
Needle thread presser
Needle
Needle guards
Case (2)
A needle guard has been improperly
positioned, causing the needle point to
strike it.
The needle is too thin for the materials.
The thread tension is too high.
The feed dog is too high, or the needle is
too low, causing the needle to deflect with
resultant needle breakage.
The needle guard C is too low, or its
longitudinal position is not correct.
The tilt of the looper is not correct. The
longitudinal motion of the looper is not
correct.
The blade point has defective shape and
does not catch needle thread loops.
The clearance or the amount of return is
not correct.
The duration in which the presser holds the
needle thread is not correct, and unstable
loop result.
The needle is bent or improperly oriented.
A needle or DC x 1 is used.
Incorrect height or clearance prohibits
correct guide for the needle. If a needle
guard is too high, loops are crushed with
consequent stitch skipping.
Check and Corrective measures
Refer to the pertinent Standard Adjustment.
Replace the needle with a thicker one.
Reduce the thread tension.
Refer to the related Standard Adjustment.
Increase the height of the needle guard (C).
Check the clearance between the needle and
needle guard.
Check the tilt of the looper. Correct the longitudinal
motion of the looper, and increase the clearance
between the looper and needle when the
looper reaches its most retracted position.
Replace the lower looper.
Refer to the relevant Standard Adjustment.
Refer to the pertinent Standard Adjustment.
Replace the bent needle. Correctly orient and
attach the needle.
Use a DC x J27 needle for a stretchy thread.
Refer to the pertinent Standard Adjustment.
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