SINGER 251 - Manual (Page 15)

1 5
T E N S I O N S
For ordinary stitching, tension on needle and bobbin
threads should be balanced so that, if you cut straight
down through center of line of stitching and look at it
from the side, the line of stitching would appear with
needle and bobbin threads locked in center of thick­
ness of material like this.
EXPLANATION
RIGHT
Needle Thread-
REGULATION
Fig. 21. Perfect Stitch
LESS
TENSION
When there is too much tension on needle thread
or not enough on bobbin thread, needle thread can
not be pulled down into material, as required and
poor stitching results. The needle thread will lie on top
of material like this:
Fig. 24. Regulating Needle
Thread Tension
First, regulate needle thread tension only when
presser foot is down.
Tension on needle thread should be ¡ust enough to
set stitch properly in material.
Having lowered presser foot, turn thumb nut at the
front of tension discs either over toward right or left,
as required. See instructions in
Fig. 24.
Bobbin Thread—
WRONG
Fig. 22. Too Tight Needle Thread
Tension
When there is too much tension on bobbin thread
and not enough on needle thread, you get the reverse
of the condition shown in Fig.
22
, above, but the
stitching is just as poor. The bobbin thread will lie on
bottom of material like this:
WRONG
Fig. 23. Too Loose Needle Thread
Tension
LESS
TENSION
Fig. 25. Regulating Bobbin
Thread Tension
When tension on bobbin thread has been properly
adjusted for ordinary stitching a correct stitch can
usually be obtained to suit the work in process by
varying tension on needle thread only.
For average sewing, tension on bobbin thread
should be very light.
To regulate tension on bobbin thread, remove the
bobbin case and turn screw in tension spring, as
instructed in Fig. 25.