4-10
Needle Thread Tension and
Guide
(Figure
16
refers)
Turn the pulley
in
the operating direction until the needle
bar reaches its lowest position.
Set the needle thread
· regulator so that the distance between its thread contact
surface and the hole
of
the needle thread take-up (C)
is
4.8 mm. Check the size
of
the loop formed as
the
needle
goes up, and raise the needle thread regulator
if
the
loop
is
smaller, and lower
it
when the loop
is
large.
Set the needle thread guide
so
that the distance between
the center
of
the ftxing screw and the thread eyelet
is
22mm.
5. TROUBLESHOOTING
8 A
Fig.
16
When trouble occurs when operation the machine, refer
to
the following table for selecting suitable measures:
Trouble
Cause
Cure
Needle
thread breaks
1. Damaged looper
Replace looper.
2. Needle thread
too
tight
Reduce tension.
3. Worn
out
feed dog causing fine stitches
Replace feed dog.
4. Thread twisting or entangling between Secure correct threading.
thread stand and needle
5.
Improper needle setting;
Set needle properly;
Bent or damaged needle
Replace needle.
6.
Needle thread
too
loose
Increase tension.
Looper thread breaks
1.
Looper thread
too
tight or
too
loose Adjust tension.
2.
Damaged looper Replace looper.
3. Thread twisting or entangling between Check for correct threading.
thread stand and looper
No
chaining on work
1.
Incorrect threading Thread machine correctly.
edges
2.
Looper thread
too
tight Reduce tension.
3.
Improper timing
of
needle and looper
Adjust timing of needle and looper.
4. Presser foot screw loosened
Tighten the screw.
Thread skips 1.
Needle setting not correct; Set needle correctly.
Bent or damaged needle Replace needle.
2. Needle thread regulator set
too
low.
Raise
regulator.
3.
Needle thread sticking on needle due
to
heat
Use
lubricant on thread.
4.
Needle bar set
too
high
Lower needle bar.
5.
Needle thread pinched by needle guard, Lower needle guard slightly.
collapsing loop
6. Looper thread
too
loose, not making a good Increase looper thread tension.
triangle
Needle or looper breaks
1. Improper timing of needle and looper Adjust timing of needle and looper.
2. Bent needle Replace needle.
Nonuniform stitch length; 1.
Weak
pressure of presser foot Increase pressure.
seam not straight. 2. Bent needle
Replace needle.
3. Worn
out
feed dog Replace feed dog.
6.
Tightening
of
Screws
and
Nuts
The tightening torque
of
major parts
is
indicated on
the catalog. Unless otherwise specified,
all
the parts
with a slot or eccentrics should be tightened with 22
to
24 kg/em.
All
other nuts, screws and bolts without
the torque requirement specifications should be tightened
as
frrmly
as
possible.
-8-
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