JUKI MB-373 Manual page 9

Adjustment Procedures
1) The knife moves in accordance with the lifting of the button
clamp. Therefore, the length of the remaining thread on the
wrong side of a fabric depends upon the height of the button
clamp at which the thread is trimmed. (In case of MB-373/
377)
For MB-372, the lifting amount of the button clamp is higher
as the button clamp cuts by its lifting force the thread lying
on the looper when the button clamp ascends at the time of
stop motion.
Loosen hook setscrew 3 and move hook 4 up or down for
adjustment.
2) Make adjustment by turning pressure adjusting nut 1.
™ Make adjustment so that the thread tension disc floats at the
time of stop motion by moving back and forth the thread
tension disc floating plate.
If the position is not proper, the disc will be likely to float
during the sewing operation.
Results of Improper Adjustment
™ Increasing the lifting amount of the
button clamp will increase the
length of the remaining thread.
Especially in case of MB-372,
thread tightness becomes strong at
the end of sewing resulting in thread
breakage and thread slip-off.
™ If the lifting amount of the button
clamp is too low, the length of the
remaining thread will become short
resulting in thread slip-off.
™ If the pressure of the button clamp
is too low, the thread end at the start
of sewing will come out on the
wrong side of the fabric unevenly
by 10 to 20 mm.
™ If the floating amount is too high, the
thread tension disc keeps floating
during sewing operation resulting in
insufficient button stitching.
™ If the floating amount is too low, the
thread length at the start of sewing
will become short resulting in thread
slip-off.
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