SINGER 15-90 - Manual (Page 26)

site the stop washer extension S, then push
the dial to compress the spring so that the
thumb nut can be t u r n e d onto the stud,
carefully guiding the pin in the thumb nut into
one of the holes in the numbered dial. Lower
the presser bar and turn the thumb nut A to the
left until it stops at “0.” Thread the tension and
pull the thread through the tension discs to test the
amount of tension at the position. At this point
there should be a barely perceptible pull on the
thread to indicate that there is a minimum tension
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 revolution of the
thumb nut. If the pull is too strong for a minimum
tension, press in the numbered dial to disengage the
pin in the thumb nut from the dial and reset the pin
in one of the holes to the left of the previous setting.
This resetting of the pin will produce less tension at
zero. 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 set­
ting. Repeat this process until the desired minimum
tension is obtained.
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 “4” and,
with two thicknesses of thin material in the machine,
adjust the bobbin thread tension, as instructed on
page 21, until the stitch is correctly locked in the
material as shown in Fig. 18.
A wide range of materials and threads can now
be accommodated without further adjustment of
the bobbin thread tension.
24