Viking Turissa Operating & Service Manual page 12

Correct and incorrect thread
tension
In order to easily understand the importance
of correct thread tension, you can try different
thread tensions by sewing two thicknesses of
fabric. Begin by using an excessively loose
tension, i.e. you turn the upper thread tension
dial to the left as far as it will go. Look at the
fabric and you will find the lower thread lies
straight and the upper thread is drawn down
into the lower side of the fabric. If you turn
the dial to the right, the opposite occurs. The
upper thread lies straight and the lower thread
comes up in loops on the top of the fabric.
The thread tension is correct when the threads
interlock in the middle of the layers of fabric
(approximately at 3 on the dial). Before starting
to sew, check the tension by sewing on two
thicknesses of the same fabric you intend to
work with.
Before you begin to use the zigzag stitch, check
that the thread tension is the same as when you
did straight stitching. Use a scrap of fabric to
see how the zigzag stitches look if you set them
first on the loosest (upper picture), then on
the higher thread tension (middle picture).
Then finally the correct thread tension will
look about like that in the lower picture. It is
important that you use the same weight thread
on the bobbin as on the spool.
Corrct
Wrong
Wrong
,-,.--
'<NN'—
Correct
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