hand, hold the bobbin case as shown, with the
thread slot near the top.
Place the bobbin into the bobbin case and pull
the thread into the slot in the edge of the bobbin
case (view B). Draw the thread down under the
tension spring and into the delivery eye at the end
of the tension spring (view C). When the free end
of the thread is pulled, the bobbin will rotate
clockwise if the bobbin case has been threaded
properly.
Replacing the Bobbin Case
Hold the latch open on the threaded bobbin
case with the thumb and forefinger of the left
hand, with the latch in a horizontal position. Place
the bobbin case on the center stud of the shuttle
body. Release the latch and press the bobbin case
back until the latch catches the groove near the
end of the stud.
Preparing for Sewing
With the left hand, hold the end of the needle
thread, leaving it slack from the hand to the
needle. Turn the balance wheel toward you until
the needle moves down and catches the bobbin
thread. Continue to turn the balance wheel
forward until the needle comes up and brings the
bobbin thread up with the needle thread.
With the thread take-up lever at its highest
position, lay both threads back under the presser
foot .
Commencing
Place the
presser foot,
to Sew
edge of the material beneath the
lower the presser foot, turn the
balance wheel by hand until the needle is in the
material, and press lightly on the treadle. To
prevent fouling the needle thread in the bobbin
case, hold the ends of both threads until the first
few stitches are made.
While sewing, hold the work flat, but do not
pull or push on the material. Let the feed dog
carry the work evenly under the presser foot and
needle. If the operator pulls on the material, the
needle bends, strikes the throat plate, and is either
dulled, or more likely, broken. When the needle
is about to cross a seam or other unusually thick
or uneven place in the work, disengage the clutch,
and hand-turn the machine over the rough place;
otherwise, the needle may be broken or thrown
out of time.
239.272
Figure 9-15.—Adjusting the machine thread tension.
Regulating the Tension
The tension on the needle thread should be
regulated only when the presser foot is down. If
the tension of the machine thread is not correct,
it should be adjusted by turning the tension
adjusting nut, as shown in figure 9-15. To
INCREASE THE TENSION, turn the nut
clockwise; to DECREASE THE TENSION, turn
the nut counterclockwise.
The tension on the bobbin thread is regulated
by the small screw in the bobbin case tension
spring. To increase the tension, turn the screw
clockwise; to decrease the tension, turn the screw
counterclockwise.
This screw is very small and is easily lost
if extreme care is not exercised in backing
it out when the tension is decreased. If the
screw is tightened excessively or is slightly
too long, it will penetrate into the inside
of the bobbin case and prevent removal of the
bobbin.
When the tension on the bobbin thread has
been properly adjusted for a particular size of
thread, it is seldom necessary to change it. A
correct stitch can usually be obtained by varying
the tension on the needle thread, which is an easier
adjustment.
9-12
