JUKI MF-7900 Series Engineer's Manual page 45

Adjustment procedures
1. Height of the front needle guard
(1) Adjust the height of front needle guard  to the position where
it is higher by 3.3 ± 0.5 mm than rear needle guard ❶ with set-
screw  .
When setscrew  is loosened, the front needle guard 
moves in the direction of rotation as well. Fix the front needle
guard  at the position where all needles are parallel to the
front needle guard  .
2. Longitudinal position of the front needle guard
(1) Adjust the position with setscrew  so that the clearance pro-
vided between the needle and front needle guard  is 0.2 to 0.5
mm when looper ❹ moves from the extreme right position to
the left and passes the rear side of the respective needles.
* Place front needle guard  as near as the needle to such
an extent that needle thread passes smoothly in accor-
dance with kind and thickness of thread.
Results of Improper adjustment
◦ When the clearance provided
between front needle guard 
and the needle is larger, loop
becomes smaller, and stitch
skipping will be caused.
◦ When the clearance provided
between front needle guard 
and the needle is smaller, loop
becomes larger, and stitch skip-
ping, blunt needle tip, or blunt
blade point of the looper will be
caused.
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