Figure 9-27.Base of machine, showing oiling points.
lubricates the upper hook bearing and the
mechanical opener mechanism.
The small, green felt pad on the side of the
bobbin case should be kept wet with oil to
lubricate the hook race. When this pad is wet, it
appears nearly black; when it appears light green,
it indicates that it is dry. When a machine is new,
oil should be applied to this felt pad EACH TIME
A BOBBIN IS REPLACED.
Needles and Thread
The thread used on rotary sewing machines is
left twist. To determine the twist of thread, refer
to figure 9-28.
Table 9-3 lists the class and variety of needles
and the needle size range for each of the class 111
Figure 9-28.How to determine the twist of thread.
The size of needle to be used is determined by
the size of the thread and material used. The
thread must pass freely through the eye of the
needle. If rough or uneven thread is used, or if
it passes with difficulty through the eye of the
Table 9-3.Data for Class 111 Sewing Machine