SINGER W1855 - Manual (Page 15)

ADJUSTING UPPER THREAD TENSION
It is only normally necessary to adjust
the upper thread tension to achieve the
correct balance between the upper and
lower threads.
The higher the number on the dial the
greater the tension.
Correct
Fabric Upper thread
Bobbin thread
Incorrect
Inside of fabric
Upper thread
LOWER THREAD ADJUSTING
TENSION
Lower thread tension can be adjusted by
turning the screw on the bobbin case
slightly to the right (clock-wise) to
increase tension, (Anti-clockwise) to the
. left to decrease tension.
As a general guide only, the user can achieve the correct
tension for normal sewing, by carefully suspending the
wound bobbin in its case by the thread. If the bobbin
and case immediately fall to the ground, the tension is too
loose and should be increased. The correct tension is
obtained when a slight jerk of the thread causes the bobbin
to drop a short distance only. If this action does not move
the bobbin the tension is too tight and should be loosened
until the desired effect is achieved.