SINGER W431 - Manual (Page 19)

CONTROLS:
ADJUSTING THREAD TENSIONS
Always adjust the upper thread
tension with the presser foot down,
as the tension is released when it is
raised. To increase the tension on
the
upper thread, turn tension
control to the right. To decrease,
turn to the left. Before adjusting
the
tension be sure that the
machine is threaded properly.
It is seldom required to adjust
the bobbin thread tension,
however, when necessary to change
bobbin thread tension, turn small
screw on side of the bobbin case
clockwise to tighten , counterclock­
wise to loosen.
When both tensions are properly
balanced, a perfect stitch will be
formed with both threads interlock­
ing in fabric (A).
When the upper tension is too tight,
the bobbin thread is pulled up over
the upper thread which is lying flat
on the fabric (B).
When the upper tension is too
loose, the upper thread forms loops
over the bobbin thread lying flat on
the fabric (C).
When the upper and bobbin thread
tensions are balanced but fabric is
puckered in sewing direction on
sheer fabrics, both tensions are too
tight. Loosen both tensions evenly.
It is recommended to adjust the
tension balance under medium
stitch length, in case of satin
stitching for buttonholes and em­
broidery slightly loosen the upper
thread tension.
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