SINGER 15-91 - Manual (Page 26)

point there should be a barely perceptible pull on the
thread to indicate that there is a minimum tension
on the thread, which gradually increases with the
turn of the thumb nut to the right, providing a full
range of tensions from light to heavy within one revo­
lution of the thumb nut. If the pull is too strong for
a minimum tension, press in the numbered dial to dis­
engage the pin in the thumb nut from the dial and
reset the pin in one of the holes to the left of the pre­
vious setting. This resetting of the pin will produce
less tension at zero. Repeat this process until the
minimum desired tension is obtained. On the other
hand, should there be insufficient tension at zero,
press in the dial and reset the pin in one of the holes
to the
right of the previous setting, repeating this pro­
cess until the minimum desired tension is obtained.
24
If Correct Stitching is Not Obtained:
If the bobbin thread tension has been disturbed,
or a correct stitch cannot be obtained without a
very heavy or very light needle thread tension, then
the following procedure is recommended:
Using No. 50 thread in the needle and on the bob­
bin, adjust the needle thread tension as instructed
above. Then turn the tension thumb nut to “3”
and, with two thicknesses of thin material in the
machine, adjust the
bobbin thread tension, as in­
structed on page 21, until the stitch is correctly
locked in the material as shown in Fig. 15.
A wide range of materials and threads can now be
accommodated without further adjustment of the
bobbin thread tension.