JUKI MO-6700D Series Manual page 60

Trouble
13. Overlocking needle thread is loose.
14. Double chain stitch needle thread
is loose.
15. Uneven overlocking stitches
The knotting position of the upper
and lower looper threads varies
as shown below.
Case (1)
Position of the needle thread take-up
guide and needle thread guide
Thread tension
Needle
Thread tension
Thread cam
Needle
Double-chain stitch needle thread
take-up guide
Looper thread tension
Looper thread take-up
Knife width
Thread path
Presser foot
Thread stand
Case (2)
They are positioned too high, and the thread
take-up draws out excessive needle thread.
The thread tension balance has been
disturbed.
The needle is too thin for the thread used.
The looper thread tension is too high, and
the needle thread tension is too low.
The thread cam draws out an insufficient
amount of thread.
The thread cam timing is bad.
The needle is too thin for the thread used.
Drawing amount of the needle thread is
insufficient.
The upper and lower looper thread tensions
are not enough.
The looper thread take-up (left) is too high.
The knife width is unsuited for the
overedging width.
Scratches on the thread path catch thread.
The presser foot cones into contact unevenly
with the throat plate and feed dogs and tends
to meander.
Thread dose not come out smoothly.
Check and Corrective measures
Refer to the pertinent Standard Adjustment.
Refer to the Standard Adjustment for the looper
thread take-up components, and increase the
tension if necessary.
Replace it with a proper one.
Reduce the looper thread tension to a minimum,
and increase the needle thread tension.
Refer to the relevant Standard Adjustment.
Refer to the relevant Standard Adjustment.
Replace the needle with a proper one.
Refer to the relevant Standard Adjustment.
Slightly increase the upper and lower looper
thread tensions.
Slightly lower the looper thread take-up (left)
Make the overedging width slightly smaller than
that given for the knife width.
Check the thread path for scratches.
Make the presser foot come into contact with
them evenly.
Make the thread come out smoothly.
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