SINGER W1266 - Manual (Page 11)

10
ADJUSTING THE TENSIONS
Always adjust the upper tension with the presser foot down,
as the tension is automatically released when it is raised. To
increase the tension on the upper thread, turn dial (Fig. 15 ) to
the right, or clockwise. To decrease, turn to the left. The higher
the number on the dial the tighter the tension. Before adjusting
lower tension be sure that the machine is threaded properly.
When necessary to change the bobbin tension, turn small
screw (Fig. 17) on side of the bobbin case clockwise to tighten,
counterclockwise to loosen.
Fig. 15
Fig. 16A Fig. 16B
When the upper and under tensions are properly
balanced, a perfect stitch will be formed with both
threads interlocking in fabric (Fig. 16-A).
When the upper tension is too tight, the lower
thread is pulled up over the upper thread which is
lying flat on the fabric (Fig. 16-B).
When the upper tension is too loose the upper
thread forms loops over the lower thread lying flat
on the fabric (Fig. 16-C).
Fig. 16C