will loosen the upper thread tension causing the
bobbin tension to draw the stitch into the material.
A clockwise turn will tighten the upper thread,
thus drawing up any stitch that may be locking
below the material.
If you cannot correct the tension by
adjusting the thread tension disc, adjust the
bobbin tension. To do this, tighten or loosen the
small screw nearest the center of the spring. This
completes all the necessary timing and adjusting
on the 111 W 155 sewing machine. If you still have
a problem, refer to the troubleshooting portion
of this chapter.
TROUBLESHOOTING
While making adjustments or timing the
sewing machine, you may overlook a step or a
faulty part. The troubleshooting chart (table 4-4)
will help you locate and correct most problems.
If the sewing machine is binding (hard to
turn), you can locate the problem easily. First,
check the feeding action; then set the machine on
zero feed and remove the throat plate. Turn the
machine by hand. If the bind is still present,
remove the arm shaft connection belt. If the bind
is located in the hook-driving shaft, the machine
will turn freely. Turn the balance wheel by hand.
If the bind is located in the arm shaft, the bind
will still be present.
SINGER SEWING MACHINES 31-15,
331K1, AND CONSEW C-30
Singer Sewing Machine 31-15, the 331K1, and
the Consew C-30 are oscillating-type sewing
machines that have a maximum speed of 2,200
stitches per minute. These sewing machines also
make the standard lockstitch and are commonly
called tailoring machines. As with the 111 W 155
Figure 4-12.—Upper thread unit.
4-11
