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.

Table 4-4.\Troubleshooting Chart A. Troubleshooting Chart Trouble Probable Cause Remedy

Table 4-4.\Troubieshooting Chart-Continued

Table 4-4.\Troubleshooting Chart-Continued

Table 4-4.\Troubleshooting Chart\Continued

Table 4-4.\Troubleshooting Chart-Continued

alternating-pressure-foot sewing machine, we will use the 31-15 sewing machine as a model for these three sewing machines. The 31-15 sewing machine is intended for sewing clothing such as flight suits and is excellent for sewing lightweight canvas up to 8 ounces.

The 31-15 sewing machine has a stitch range of 7 to 32 SPI, a clearance of five-sixteenths of an inch under the presser foot, and uses a dropfeeding action. The major components of the Singer Sewing Machine 31-15 are shown in figure 4-13.

PREVENTIVE MAINTENANCE

Preventive maintenance for the Singer Sewing Machine 31-15 is the same as that for the 111 W 155 sewing machine. Although the preventive maintenance is the same, the oiling points differ because of the design of the machine. Figures 4-13 through 4-15 show the different oiling points for the 31-15 sewing machine. When you oil this machine, remember 1 drop of a 10W mineral oil at each oiling point is sufficient. Too much oil may soil the project being sewn.