JUKI LK-1900AN, Engineer'S Manual, Page: 49 / 140

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Adjustment procedures Results of Improper adjustment
After thread cutting, the wiper spring
1
is used to hold the needle
thread with the aid of the wiper
2
. Adjust the wiper spring
1
and
fix it with the set screw
3
so that the intensity of the spring force be-
comes 20 to 30g (somewhat stronger than that of the bobbin thread
that is protruded from the bobbin case).
1. Remove the set screw
3
and take out the wiper spring
1
from
the wiper
2
.
2. Adjust the wiper spring
1
and mount it on the wiper
2
again
by means of the screw
3
.
(Caution) 1. If the holding force is too strong, the thread
may be protruded above the button.
2. If the holding force is insufficient, needle
thread castoff may occur.
3. If the wiper spring
1
position is inadequate,
the needle thread cannot be held correctly and
this can be a cause of needle breakage.
Adjustment procedures Results of Improper adjustment
1. Loosen the two setscrews
2
and four setscrews
4
of the Y
feed motor
1
and the two setscrews
4
of the X feed motor
mounting plate
5
.
2. Pressing it in the direction of the arrow
C
, tighten the two
upper setscrews
2
in the first place. Then, tighten the two
remaining setscrews
4
and another two setscrews
4
, X feed
motor mounting plate
5
.
3. Loosen the four setscrews
7
of the X feed motor
6
. Pressing
it in the direction of the arrow
B
, tighten the setscrew
7
.
o
If the pressing force is insuf-
ficient, feed gear backlash
becomes too much and needle
location accuracy may be
decreased. This can also be
a cause of feed error, needle
breakage, etc.