JUKI MF-7900 Series Engineer's Manual page 31

Adjustment procedures
1. Adjusting the height of the spreader
2. Adjusting the longitudinal position of the spreader
Loosen setscrew ❸ and adjust the height and longitudinal posi-
tion of the spreader ❶ .
3. Protruding amount of the spreader
Loosen setscrew ❹ in the spreader folder and adjust the pro-
truding amount. Adjust aiming the adjustment figure of 5 mm.
4. Adjusting the spreader stroke
The standard position is located where the notch section of
spreader drive lever ❺ aligns with the shaft center of con-
necting pin ❻ . When desired to increase the stroke, loosen
lock nut ❼ and move in the right direction. When desired to
decrease the stroke, loosen lock nut ❼ and move in the left
direction. Adjust aiming the adjustment figure of 17.5 mm.
❼
❺
5. Adjusting the timing between the needle bar and the spreader
When changing the timing, loosen two setscrews ❾ in spread-
er eccentric cam ❽ to adjust. Standard position is the position
where notch B in the main shaft aligns with notch C in spread-
er eccentric cam. When changing, turn the upper pulley and
change with spreader eccentric cam ❽ fixed.
❽
C
❻
❾
B
– 17 –
Results of Improper adjustment
◦ Height of the spreader is improp-
er, stitch skipping of spreader
occurs.
◦ Adjust the height in accordance
with the needle gauge.
◦ Even when the protruding
amount is excessive or insuffi-
cient, stitch skipping of spreader
will be caused.
◦ When the protruding amount is
insufficient, it will be the cause
for left needle not to scoop
covering thread at overlapped
section.
◦ When the stroke is increased,
disorder of covering thread
stitching will be caused.
◦ When the stroke is decreased,
stitch skipping of spreader will
be caused.
◦ When the timing is excessively
advanced, needle does not take
covering thread when it comes
down and stitch skipping will be
caused.
◦ When the timing is excessively
retarded, resistance increases
when covering thread slips out
from the spreader and a load is
applied to the right needle. As a
result, needle breakage or stitch
skipping will be caused.
(Caution) When changing, tem-
porarily tighten No. 2
screw in the rotation
direction of setscrews
❾ and turn the upper
pulley to change.