JUKI LK-1900AN Engineer's Manual page 53

Adjustment procedures
1. Adjust the position of the bobbin winder driving wheel 1 and
fix it with two setscrews 2 .
Adjustment procedures
1. Loosen the setscrew 3 of the bobbin winder lever and adjust
the distance to 14 mm between the bobbin winder lever 1 and
the bobbin winder shaft 2 . After that, tighten the setscrew 3 of
the bobbin winder lever.
2. Start the sewing machine and wind the thread at the bobbin
winder. Confirm the amount of winding.
1) If the amount of winding seems to be too much, adjust the
bobbin winder lever 1 in the direction of the arrow A .
2) If the amount of winding seems to be too less, adjust the
bobbin winder lever 1 in the direction of the arrow B .
3. If the winding state of the thread 7 around the bobbin 8
seems to be uneven, loosen the nut 5 and adjust the height of
the thread tension control 4 .
(Example) If the amount of the wound thread is less on the
upper side of the bobbin 8 as illustrated, adjust the
thread tension control 4 upwards.
Results of Improper adjustment
If the distance of 10 mm is insuf-
o
ficient, rubber ring wear may
occur in the bobbin winder unit.
In addition, the bearing life may
be reduced in the bobbin winder
unit.
If the distance of 10 mm is ex-
o
cessive, normal thread winding
may fail. In addition, this will also
cause rubber ring slippage in the
bobbin winder unit and give rise
to wear.
Results of Improper adjustment
If too much thread is wound
o
(thread protruded from the bob-
bin 8 ), the thread 7 will come
in contact with the inside of the
bobbin case and this can be a
cause of sewing deficiency.
If the amount of thread winding
o
is uneven at top and bottom of
the bobbin 8 , stitch perforation
may become irregular.
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