JUKI MO-6000S series Engineer's Manual page 88

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.
Slighrly 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 evently.
Make the thread come out smoothly.
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