Regulating The Thread Tension; The Bobbin Thread Tension - Pfaff 260 Service Manual

The Thread Tens ion
Both threads must be under proper tension to ensure a correct setting of
stitches. Depending on the type of fabric being sewn and the thread size
used, both tensions must be balanced so that the lock of the needle ond bob-
bin threads occurs exactly in the center of the material. The correct amount
of tension
on the need le thread is set by the upper tension (tension discs) on the
front of the machine (Fig. 29), and
on the bobbin thread, by the lower tension (flat spring) on the bobbin
case (Fig. 28).
The upper tension is so designed that all grades of tension, from loose to
tight, con be covered with one complete turn of the tension dial. Any desired
degree of tension con be set by the numbers indicated on the dial. This setting
can be quickly restored if the tension should hove been altered for some
special sewing job.
The needle thread tension has a third tension disc for two-needle work so
that both threads are separated in the tension mechanism.
The Bobbin Thread Tension
To balance the tensions correctly, begin by setting the bobbin thread tension
at a medium grade. To this end, tighten the regulating screw until a notice-
able resistance has to be overcome when pulling the thread.
Determine the correct bobbin thread tension by holding the thread end
between your fingers and letting the bobbin case hang freely. The tension
should be strong enough to keep the bobbin case from being pulled down by
its own weight. However, as you jerk your hand slightly, the bobbin
case
should gradually slide down (Fig. 30).
Regulating the Thread Tension
No screwdriver is required to adjust the bobbin thread tension on Pfaff 260
and 360 machines. Instead, the knurled screw on the bobbin case con be
turned with the thumb tip, as follows:
Turn it left for a looser tension,
and right, for a tighter tension.
Do not turn the knurled screw too for out so that it will not fall out and get
lost.
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