– 9 –
o Excessive return of the lower
looper tends to cause stitch
skipping when filament thread is
used.
o Insufficient return of the lower
lopper tends to cause needle
thread stitch skipping when spun
thread is used.
o Excessive clearance will often
cause needle thread stitch
skipping.
o Insufficient clearance will cause
needle breakage due to the con-
tact of the looper with the needle,
or produce scratches on the
blade point of the looper, lead-
ing to needle thread breakage or
other troubles.
1) Returning amount of the lower looper
1
Loosen setscrew
of lower looper support arm
and adjust lower
looper
to make adjustment of the returning amount.
(Referential information)
1. Radius
K
of lower looper
will be 66.9 mm when the lower
looper is inserted into lower looper support arm
until it con-
tacts with stopper pin
and then is fixed.
2. The rocking angle of the lower looper will be 26
°
.
2) Clearance between the lower looper and the needle
1
Loosen setscrew
of lower looper support arm
to the extent that
it is temporarily tightened. Then finely adjust the longitudinal position
of the looper using fine adjustment screw
.
2
Turn fine adjustment screw
clockwise to move lower looper
away
from the needle.
Turn the screw counterclockwise to move lower looper
closer to it.
Adjustment Procedure
Results of Improper Adjustment
Summary of Contents for MO-6700D Series
Page 49: ...45 2 Upper looper components...
