JUKI MF-7800D Series Engineer's Manual page 35

Adjustment Procedure
1. Height of the front needle guard
(1) Adjust the height of front needle guard
higher by 3.3 ± 0.5 mm than rear needle guard
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
between the needle and front needle guard
when looper moves from the extreme right position to the left and
passes the rear side of the respective needles.
* Place front needle guard
that needle thread passes smoothly in accordance with kind and
thickness of thread.
to the position where it is
with setscrew
so that the clearance provided
is 0.2 to 0.5 mm
as near as the needle to such an extent
– 31 –
Results of Improper Adjustment
o When the clearance provided
between front needle guard
and the needle is larger, loop be-
.
comes smaller, and stitch skip-
ping will be caused.
o When the clearance provided
between front needle guard
and the needle is smaller, loop
becomes larger, and stitch
skipping, blunt needle tip, or
blunt blade point of the looper
will be caused.