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6. Defective thread trimming
6-1) Sharpness of the knife is
1-A) Abrasion of moving and
Replace the moving and counter knives.
difective
counter knives.
1-B) Engagement of the moving
Properly adjust the heigh and position of the moving
and counter knives is defective.
and counter knives.
1-C) Parallel of the blade section
Properly adjust the parallel of the blade section of
of counter knife is defective.
counter knife.
1-D) Attaching position of the
Properly adjust the attaching position of counter knife.
counter knife is defective.
6-2) Double cutting for the needle
2-A) There is a burr on thread spreading
Paying attention to the blade section, polish with
thread. (Thread waste remains
section
A
of the moving knife.
polishing power, or replace the moving knife.
inside the cylinder arm cap.)
The shape of the thread
trimmed becomes and
thread waste remains.
2-B) Shuttle upper spring has scratches.
Remove the scratches.
(The shape of the thread trimmed
becomes and thread waste
remains.)
6-3) Moving knife does not spread
3-A) Initial position of the moving
Adjust the initial position of the moving knife.
threads.
knife is maladjusted.
3-B) Thread trimmer cam position
Adjust the thread trimmer cam position.
is inadequate.
3-C) Position of the shuttle upper
Adjust the position of shuttle upper spring .
spring is defective.
6-4) Stitch skipping at the final stitch
4-A) Timing of the needle to the
Adjust the timing and the clearance.
inner hook and the clearance
between them are defective.
4-B) Work clamp foot big.
Let the biginning of stitch come closer to the presser
by moving the pattern.
4-C) Loop of the needle thread
Attach the needle with the long groove orienting
falls down.
slightly to the right (approximately 20
°
)
6-5) Bobbin thread cannot be cut.
5-A) Bobbin thread tension is low.
Streng then the bobbin thread tension.
5-B) Needle hole size of the needle
Replace the needle hole guide with a new one having
hole guide is large.
a smaller hole diameter.
Trouble
Cause (1)
Cause (2)
Check and corrective measures
A
