−
57
−
8. TROUBLES AND CORRECTIVE MEASURES (WITH REGARD TO SEWING)
1.
Thread
breakage
1-1)
Stitches are
not properly
formed.
(Lower cloth)
Thread knots are
made.
Thread breakage
occurs when the
needle throws to
the right.
Smaller thread loops are produced.
Larger thread loops are produced and they
tilt.
An excessive clearance is provided
between the blade pointer the hook and
the needle.
The material flops.
Stroke of the thread take-up spring is too
large.
The hook timing is excessively advanced.
The auxiliary thread take-up lever
excessively works.
Both the needle thread tension and bobbin
thread tension are too high.
Height of the needle bar is defective.
Stroke of the thread take-up spring is too
small.
The hook timing is excessively retarded.
The auxiliary thread take-up lever fails to
work.
Both the needle thread tension and bobbin
thread tension are too low.
Height of the needle bar is defective.
Needle slot in the throat plate is too Iarge.
The sole of the presser foot is not closely
fitted onto the throat plate surface.
The recess on the sole of the presser foot is
too large.
The needle sticks in fabric yarn and the
thread is retained by the fabric yarn.
(Particularly when power net is sewn with
span thread)
The needle has a blunt tip.
Reduce the stroke of the thread take-up spring.
Re-adjust the hook timing properly using a timing gauge.
Lower the auxiliary thread take-up lever.
Reduce the tension to balance the needle thread and bobbin
thread.
Properly adjust the height of the needle bar using a timing gauge.
Lengthen the stroke of the thread take-up spring.
Re-adjust the hook timing properly using a timing gauge.
Properly adjust the auxiliary thread take-up lever.
Increase the needle tension to balance the needle thread tension
and bobbin thread tension.
Properly adjust the height of the needle bar using a timing gauge.
If the needle guard works excessively, raise the needle guard.
Adjust the needle-to-hook relation again.
Replace the throat plate with another throat plate which has a
smaller needle slot.
Loosen the screw in the presser foot, and re-tighten it with the
presser foot closely fitted onto the throat plate.
Replace the presser foot with another one which has a smaller
recess.
Use a needle which has a round tip. We recommend the 438SKL
needle.
Replace the needle with a new one.
Trouble
Description
Cause 1
Cause 2
Corrective measure and adjusting procedure
Thread breakage
occurs when the
needle throws to
the left.
