Industrial Sewing Machine SADE
121
Troubles Causes Corrective measures
2. Stitch skipping
Timing between the needle
and the hook is excessively ad-
vanced or retarded.
○ Refer to "6.5. Needle-to-hook re-
lation" p. 61.
Pressure of the presser foot is
too low.
○ Tighten the presser spring regula-
tor.
The clearance provided be-
tween the top end of the needle
eyelet and the blade point of hook
is not correct.
○ Refer to "6.5. Needle-to-hook re-
lation" p. 61.
Hook needle guard is not func-
tional.
○ Refer to "6.6. Adjusting the
hook needle guard" p. 63.
Improper type of needle is
used.
○ Replace the needle with one
which is thicker than the current
needle by one count.
3. Loose stitches
Bobbin thread does not pass
through the tension spring of the
inner hook.
○ Thread the bobbin thread correct-
ly.
Thread path has been poorly
finished.
○ Remove rough parts with a fine
emery paper or buff it up.
Bobbin fails to move smoothly.
○ Replace the bobbin or hook with a
new one.
Bobbin case opening lever
provides too much clearance at
the bobbin.
○ Refer to "6.7. Adjusting the
bobbin case opening lever" p. 63.
Bobbin thread tension is too
low.
○ Increase the bobbin thread ten-
sion.
Bobbin has been wound too
tightly.
○ Decrease the tension applied to
the bobbin winder.
4. Thread slips off the
needle eyelet simul-
taneously with
thread trimming.
Thread tension given by the
tension controller No. 1 is too
high.
○ Decrease the thread tension given
by the tension controller No. 1.
5. Thread slips off the
needle eyelet at the
start of sewing.
Thread tension given by the
tension controller No. 1 is too
high.
○ Decrease the thread tension given
by the tension controller No. 1.
The clamp spring has de-
formed.
○ Replace the clamp spring with a
new one or correct the current one.
Bobbin thread tension is too
low.
○ Increase the bobbin thread ten-
sion.
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