JUKI MO-6700D Series Manual page 62

Trouble
20. Uneven material feed
21. Puckering
(Mainly concerned with double chain
stitch)
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Case (1)
Presser foot pressure
Presser foot
Tilt of feed dogs
Height of feed dogs
Adjustment of differential feed
Needle
Thread
Thread tension
Throat plate
Thread cam timing
Feed dogs
Case (2)
The presser foot pressure is too high.
The hinge is too stiff.
Scratches on or defective finish on the
presserfoot sole produce friction between
the presser foot and materials.
The front is too high.
A different in level exists between the main
feed dog and differential feed dog.
The differential feed has been improperly
adjusted.
The needle is too thick.
The thread used is too thick.
Both the needle thread and looper thread
tensions are too high.
The throat plate has a large needle hole.
The thread cam timing is too late
The leading edge of the feed dog teeth
has been rounded off.
A difference in level exists between the
main feed dog and differential feed dog.
Check and Corrective measures
Reduce the presser foot pressure except for
the uneven material feed due to puckering.
Remove the stiffness provided no hinge play
is produced.
Buff the presser foot sole for good surface
finish.
Make the front down. However, be sure to align
the differential feed dog with the main feed dog.
Eliminate the difference in level.
Provide differential feed suited to the material.
Use a thin needle as much as possible.
Use a thin needle as much as possible.
Reduce the both thread tensions to a minimum.
Replace the throat plate with one with a small
needle hole.
Advance the cam timing. Refer to the related
Standard Adjustment.
Replace the feed dog.
Eliminate such difference in level.
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