JUKI MEB-3200 Engineer's Manual page 39

Adjustment Procedures
1. Adjusting the looper thread presser
1) Loosen setscrew 3.
2) Fully press downward throat plate 1 and install it.
3) Lightly press upward the looper thread presser so that a
clearance is not provided between looper thread presser 2
and the bottom surface of throat plate 1. Then tighten setscrew
3.
4) Loosen nut 8 and tighten adjusting screw 7 until the top end
of the screw comes in contact with looper bracket 9.
5) Further, turn it by 1/4 turn and fix it with nut 8.
6) Loosen nut !2 .
7) Press section C of installing base ! 3 in the direction of arrow
mark D with finger, tighten adjusting screw !1 so that the thread
guide section of looper thread presser 2 protrudes from throat
plate 1 by approximately 0.5 mm and fix the screw with nut
! 2 .
2. Adjusting the looper thread trimming knife
1) Loosen setscrew ! 5 and adjust so that the top end of looper
thread trimming knife 4 is located at the position of 1 to 2 mm
from section A of throat plate 1 and that a clearance of 0.2 to
0.4 mm is provided between the bottom surface of the looper
thread trimming knife and throat plate 1.
2) Loosen nut 6.
3) Tighten adjusting screw 5 so that the blade point of looper
thread trimming knife 4 protrudes from end plane E of throat
plate 1 by approximately 1 mm. Then fix it with nut 6.
4) Press section B of knife installing base !4 in the direction of
arrow mark D with finger, tighten adjusting screw ! 0 (double
thread screw) so that the top end of looper thread trimming
knife 4 aligns with the end plane of throat plate 1. Then fix
the base. The standard of the protruding amount of adjusting
screw !0 is 1.4 mm.
(Reference) When the looper thread is not retained
immediately after threading or the like, perform sewing after
retaining the looper thread at section A of throat plate 1
with looper thread presser 2.
Results of Improper Adjustment
™ When the clearance provided
between throat plate 1 and the
looper thread presser is smaller
than the specified value, the
looper thread holding force is
insufficient. As a result, stitch
skipping at the start of sewing
or defective roll-in of thread will
be caused.
™ When the looper thread presser
is excessively pressed to throat
plate 1, component breakage
or excessive tightness of
stitches at the start of sewing will
result.
™ When the lateral position of
looper thread trimming knife 4
is not obtained, thread trimming
failure or interference with the
presser will result.
™ When looper thread trimming
knife 4 is positioned too high,
looper thread trimming failure or
cut-off of stitches will result.
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