2. Improper seam
Upper thread is too tight and pulls up the
under thread. The under thread appears on
the upper surface of the material.
Solution:
Reduce the tension of the upper thread
by turning the upper thread tension dial (20)
to a lower number.
3. Improper seam
Upper thread is too loose. The under thread
pulls down the upper thread. The upper
thread appears on the under side of the
material.
Solution:
Increase the tension of the upper thread
by turning the upper thread tension dial (20)
to a higher number.
4. Suggestion for zigzag stitch
For getting better zigzag stitches, the upper
thread tension must be looser than for sewing
straight stitches.
The upper thread should be slightly visible on
the under side of the material.
1
21
2
3
4
1. Proper seam
The upper and under thread tension is
properly set, when it is just so tight that the
threads are intertwined in the center of the
thickness of the material.
The fabric remains smooth and does
not pucker.
Note:
In both cases of improper seams
(figures 2 and 3),it may also be necessary to
change the under thread tension.
Checking the upper and under thread tensions
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