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 machines.

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

needle, the machine will not function properly.

Needles used on rotary sewing machines are ordered the same way as those for oscillating sewing machines.

The needles for rotary sewing machines have seven parts. This is one more part other than the needles for the oscillating machines. The additional part is the SCARF, which is a small indention just above the short thread groove. The purpose of the scarf is to permit the point of the sewing hook to come close enough to pick up the needle thread without striking the needle.

Operation

Operation of rotary sewing machines is the same as for the oscillating sewing machines.

Setting the Needle

Turn the balance wheel toward you until the needle bar moves up to its highest position. Loosen the setscrew in the needle bar and slip the needle up into the bar as far as it will go. The needle must be inserted with its long thread groove toward the left, the eye of the needle being directly in line with the machine bed. Retighten the setscrew.

Threading the Machine

Pass the thread from the thread stand from back to front (fig. 9-29) through the lower hole (1) in the thread post on top of the machine, then from right to left through the upper hole (2) in the post. Pass the thread down through hole (3), up through hole (4), and down through the hole (5) in the thread guide on the front of the machine. Continue the thread over from right to left between the tension disks (6), and down, from right to left, around the thread controller (7). Then the thread should go up into the fork (8) in the thread controller disk against the pressure of the wire controller. The thread is then passed up through the thread guide (9), and from right to left through the hole in the thread take-up lever (lo).

Pass the thread down through the thread guide (11), and between the felt pad and the felt pad retainer finger (12). (If the machine you are threading does not have the felt pad and retainer

Figure 9-29.-Threading the class 111 sewing machine.

finger installed, bypass this component.) Finish the threading by passing the thread down through the thread guide (13), through the thread guide (14) at the bottom of the needle bar, and from left to right through the eye of the needle (15). Always thread a needle toward the bobbin.