SINGER SEWING MACHINE 143 W 2 AND 3
This type of machine is not as common as those previously described, but it has unlimited uses in the repair and maintenance of parachutes and survival equipment.
The 143 W 2 is a high-speed sewing machine that has an aluminum alloy vibrating needle bar frame and a rotary hook. It is intended for overseaming and zigzag stitching on fine and general fabrics and lightweight leather. It has ball bearings on the rear end of the arm shaft and hook driving shaft. The needle bar has a maximum throw of 3/16 inch, vibrating both sides of a centerline.
The 143 W 3 sewing machine is similar to the 143 W 2 except that the needle has a maximum throw of 5/16 inch.
The maximum speed recommended for machine 143 W 2 is 3,500 stitches per minute, and for machine 143 W 3, 3,000 stitches per minute, the speeds depending on the material being sewn.
Needle and Thread
The needles for the 143 W 2 and 143 W 3 sewing machines are of class and variety 135 x 7; the sizes from 7 to 24.
Left twist thread should be used on these machines. To make a smooth even stitch with the sewing machine, use good, firmly twisted and smoothly finished thread. The thread should pass freely through the eye of the needle.
Setting the Needle
Push the needle up in the needle bar as far as it will go, with the LONG THREAD GROOVE TO THE FRONT, and secure it firmly with the setscrew. It may be necessary to turn the needle slightly to the right or left for some threads if stitches are missed.
Bobbin and Bobbin Case
The procedure for removing the bobbin case, winding the bobbin, threading the bobbin case, and replacing the bobbin case is the same as for the 31-15 sewing machine. The only exception to this is that when the bobbin case is threaded, the thread should be drawn from the BOTTOM from left to right, instead of from the top as given for the 31-15.
Threading the Needle
These machines are threaded in the same way as the 111 series machines, described earlier in the chapter. When threaded up to the needle, thread the needle from the front through the eye to the back. The long thread groove should be in front when the needle is properly set in the needle bar.
Regulating the Length of Stitch
To adjust the length of stitch, depress the stitch regulator lever (fig. 9-39) on the uprise and, at the same time, turn the balance wheel forward until the lever engages in the notch in the stitch regulator flange. Hold the lever in the notch and turn the balance wheel backward or forward (as necessary) until the desired number of stitches per inch is shown opposite the arrow on the stitch regulator.
Regulating the Width of the Zigzag
The extreme width of the zigzag (needle throw) on the 143 W 2 is 3/16 inch; it is 5/16 inch on the 143 W 3. The width of bight is regulated by turning the knurled knob on the needle vibrator regulating spindle head (fig. 9-39) at the front of the machine. To increase the width of the stitch, turn the regulating spindle head to the left, and to the right to decrease.
Setting the Needle Bar
The two adjustment marks on the needle bar are 3/32 inch apart. To set, insert the needle bar up into the needle bar frame so the upper mark is just visible at the lower end of the needle bar frame with the bar at its lowest position. The eye of the needle should be 1/16 inch below the point
Figure 9-39.-Oiling points at the front of the 143 W 2. 9-31
of the hook, and the long thread groove toward the operator.
Setting and Timing the Needle Bar Frame
Turn the regulating spindle head all the way to the right. This will cause the machine to sew a straight stitch. The needle should be centered in the hole in the throat plate. If not, loosen the setscrew that holds the eccentric stud (1) and turn the stud until it is centered (fig. 9-40.) Turn the needle regulating spindle head (5) to the extreme left for the widest throw. Turn the balance wheel forward until the needle is at its lowest position. The needle bar should start to move in a sideward movement as the needle starts to rise. If it does not, you must advance or retard the vibrator pinion gear (2), shown in figure 9-40.
Timing Sewing Hook
Turn the balance wheel toward the operator's side until the needle bar is all the way down and has risen until the lower timing mark is just visible below the needle bar frame. Loosen the setscrews (10) in the lower belt pulley (fig. 9-41) and set the hook point to the center of the needle eye. Retighten the setscrews.