JUKI MO-6700D Series Manual page 21

Adjustment Procedure
1
1) Returning amount of the double chain looper
Loosen setscrew
2
this adjustment.
Radius of the double chain looper driving arm
M
when it is lowered until it comes in contact with stopper pin
1
2) Longitudinal motion (Avoid motion)
Open the cover of the adjusting hole on the rear of the frame, loosen
setscrew , and put a Ø2 rod in the hole. Now, make the adjustment
by turning the rod back and forth.
Marker : This side
..... Minimum (for standard to thin needle)
Marker : Far side
..... Maximum (for thick needles)
1
3) Clearance between the double chain looper and the needle
Temporarily tighten setscrew
adjust the longitudinal position of the double chain looper. Adjust the
clearance to 0.05 to 0.1 mm.
of double chain lopper driving arm
B
in the double chain looper, and finely
Results of Improper Adjustment
to make
will be 63.4 mm
.
As observed
A
from this side
– 17 –
o Excessive return of the double
chain looper will cause frequent
stitch skipping when filament
thread is used.
o Insufficient return of the double
chain looper will cause frequent
thread stitch skipping when a
spun thread is used.
o If the avoid motion is too large,
triangle stitch skipping will often
occur.
Bad needle
entry
Good needle
entry
o Insufficient avoid motion will
cause the needle point to hit the
looper, producing scratches on
the needle point or looper.
o Excessive clearance will cause
frequent needle thread stitch
skipping.
o Insufficient clearance will cause
to looper to hit the needle, lead-
ing to needle breakage or
scratches on the looper blade
point with consequent thread
breakage.