JUKI MO-6000S series Engineer's Manual page 37

Adjustment Procedures
1) When the knives have become dull, fully resharpen lower knife
1 until the contact mark of it disappears.
2) When the upper knife has become dull, replace it with a new
one. (This is because the upper knife is a serrated carbide
knife.)
1) Adjusting the thread cam
1 Adjust the position of the thread cam by its setscrew 1 with
the needles at their upper dead point so that the straight section
of the thread cam is leveled.
2 Laterally position the thread cam so that the looper thread cam
nail is located at the center of the thread cam groove.
[How to check for proper positioning]
Check that the thread cam releases the looper thread when the
needle tip begins to come out of the bottom surface of the throat
plate by 0 to 1 mm.
Thread
2) Adjusting the looper thread cam thread guides A and B
and the looper thread cam nail
1 Install looper thread cam thread guides A 2 and B 3 at the
center of the slots with setscrews A 4 and B 5.
2 Install looper thread cam nail 6 with setscrew 7 so that the
straight section of the forked portion is leveled.
Throat plate
0 to 1 mm
33
Results of Improper Adjustment
™ If the 10˚ angle of the lower knife
is exceeded, the durability of the
knife will be deteriorated, often
resulting in blade chipping.
™ If the angle is smaller than 10˚,
the knife will be dull.
™ If the 55˚ angle is not observed,
the knife may catch materials.
™ If the timing of the thread cam
is too early, the needle point will
fail to enter a thread triangle,
resulting in looper thread stitch
skipping.
™ If the timing of the thread cam
is too late, puckering and loose
looper thread stitches will
results.
™ If the chain looper thread guide
is moved away from you, the
take-up amount of the lower
looper thread will decrease. In
this case, puckering may result
there by impairing the feeling of
the finished product.