Singer 31-20 Instructions Manual

To regulate the tension on the needle thread, ensure the presser foot is down. Turn the small thumb nut (D, Fig. 2) at the front of the tension discs over toward the right to increase tension, and over toward the left to decrease tension. To regulate the tension on the bobbin thread, use the larger screw (1, Fig. 9) in the tension spring on the outside of the bobbin case. Turn this screw over to the right to increase tension, and over to the left to decrease tension. Once properly adjusted, it is seldom necessary to change it, as a correct stitch can usually be obtained by varying the tension on the needle thread. To adjust the tension on the thread take-up spring, it should be just sufficient to take up the slack of the needle thread until the eye of the needle reaches the material on its downward stroke. To increase the tension, loosen the tension screw stud (W) and force the take-up spring from its recess in the regulator, moving it clockwise between the regulator and the tension discs. To decrease the tension, force the spring counter-clockwise between the regulator and the tension discs. After adjustment, securely tighten the tension screw stud (W).

Was this helpful? Why is the Singer 31-20 sewing machine bunching thread on the bottom?

If the bobbin thread lies straight along the under surface of the material, it indicates that the tension on the needle thread is too loose, or the tension on the bobbin thread is too tight. To correct this, regulate the tensions by adjusting the small thumb nut (D, Fig. 2) on the needle thread tension discs (turn right to increase, left to decrease) or the larger screw (1, Fig. 9) on the bobbin case tension spring (turn right to increase, left to decrease). For more information, see page 7 of the manual.

Was this helpful? How do I change the needle on the Singer 31-20 sewing machine?

To change the needle, turn the balance wheel over toward you until the needle bar moves up to its highest point. Loosen the screw (C, Fig. 2, page 4) in the needle clamp. Put the new needle up into the clamp as far as it will go, ensuring the long groove of the needle is toward the left and the eye of the needle is directly in line with the arm of the machine. Then, tighten the screw. For more information, see page 6 of the manual.

Was this helpful? Why is the Singer 31-20 sewing machine looping thread underneath the fabric?

Was this helpful? Why is my Singer 31-20 sewing machine not stitching properly?

If the tension on the needle thread is too tight, or if the tension on the bobbin thread is too loose, the needle thread will lie straight along the upper surface of the material.
If the tension on the bobbin thread is too tight, or if the tension on the needle thread is too loose, the bobbin thread will lie straight along the under surface of the material.

To regulate the tensions, adjust the small thumb nut (D, Fig. 2) on the needle thread tension discs (turn right to increase, left to decrease) or the larger screw (1, Fig. 9) on the bobbin case tension spring (turn right to increase, left to decrease).

For more information, see page 7 of the manual.

Was this helpful? How do I set up the Singer 31-20 sewing machine for initial use?

Oil the Machine: Use "TYPE B" or "TYPE D" OIL sold by Singer Sewing Machine Company. Apply oil to all oil holes marked "Oil" and to all oiling places indicated by arrows in Figs. 2, 3 and 4. When in continuous use, the machine should be oiled at least twice each day. Loosen the thumb screw (F, Fig. 3) in the round cover plate at the back of the machine, turn the cover plate up, oil the uncovered bearings, and then replace the cover. Turn the machine on its hinges and apply oil at the places shown by arrows in Fig. 4 and all other places where parts are in movable contact. Occasionally remove the face plate and apply oil to the bearings and parts which are in movable contact.
Ensure Perfect Action: The balance wheel must always turn over toward the operator. Do not run the machine with the presser foot resting on the feed without cloth under the presser foot. Do not run the machine when both bobbin case and needle are threaded unless there is material under the presser foot. Do not try to help the machine by pulling the fabric, as the machine feeds the work without assistance. Keep the slide over the bobbin case closed when the machine is in operation.
Prepare for Sewing: With the left hand, hold the end of the needle thread, leaving it slack from the hand to the needle. Turn the balance wheel over toward you until the needle moves down and up again to its highest point, which catches the bobbin thread. Draw up the needle thread and the bobbin thread through the hole in the throat plate. Lay both threads back under the presser foot.
Commence Sewing: Place the material beneath the presser foot, lower the presser foot, and commence to sew, turning the balance wheel over toward you.

Was this helpful? Why is the Singer 31-20 sewing machine not feeding the fabric?

The feeding mechanism may not be feeding the fabric properly if the feed dog is not set at the correct height or if the feeding mechanism is not timed correctly. To adjust the feed dog height: Loosen the clamping screw (G, Fig. 17) and move the feed lifting rock shaft crank (F) until the feed dog is set at the required height, then securely tighten the clamping screw (G). The feed dog teeth should project slightly less than their full depth through the slots in the throat plate when raised to their highest point. To time the feeding mechanism: Press the stitch regulator (A, Fig. 2, page 4) down to its lowest point for the longest stitch. Turn up the round cover plate at the back of the machine. Loosen the feed eccentric set screw (S, Fig. 18) and turn the feed eccentric (R, Fig. 18) until the feed dog finishes its feeding movement (away from the operator) when the thread take-up lever (7, Fig. 11, page 9) is at its highest point. The feed should always finish its feeding movement before the needle reaches the goods on its downward stroke. Then securely tighten the set screw (S). For more information, see page 9 of the manual.

Was this helpful? How do I correctly insert the bobbin into the Singer 31-20 sewing machine?

To insert the bobbin into the bobbin case, hold the bobbin between the thumb and forefinger of the right hand, with the thread drawing on the top from the left toward the right. Then, with the left hand, hold the bobbin case with the slot in the edge being near the top, and place the bobbin into it. Pull the thread into the slot in the edge of the bobbin case, draw the thread under the tension spring, and into the delivery eye at the end of the tension spring. To replace the bobbin case in the machine, take the bobbin case by the latch, holding it between the thumb and forefinger of the left hand. Place the bobbin case on the centre stud of the shuttle body with the position finger opposite the notch at the top of the shuttle race. Release the latch and press the bobbin case back until the latch catches the groove near the end of the stud. Allow about two inches of thread to hang free. For more information, see page 6 of the manual.

Was this helpful? How do I wind thread onto the bobbin for the Singer 31-20 sewing machine?

To wind thread onto the bobbin, first fasten the bobbin winder to the table with its driving pulley in front of the machine belt, so that the pulley will drop away from the belt when sufficient thread has been wound. Place the bobbin on the bobbin winder spindle and push it on as far as it will go. Pass the thread down through the thread guide (1) in the tension bracket, around the back and between the tension discs (2). Then, wind the end of the thread around the bobbin a few times, push the bobbin winder pulley over against the machine belt, and start the machine. The bobbin winder will stop automatically when sufficient thread has been wound. If the thread does not wind evenly, loosen the screw (A) in the tension bracket and move the bracket to the right or left as needed, then tighten the screw. The amount of thread wound is regulated by screw (B); turn it clockwise to wind more, and counterclockwise to wind less. Bobbins can be wound while the machine is stitching. For more information, see page 5 of the manual.

Was this helpful? How do I thread the bobbin on the Singer 31-20 sewing machine?

Was this helpful? How often should I oil the Singer 31-20 sewing machine? The machine should be oiled at least twice each day when it is in continuous use. Was this helpful? What type of needles are compatible with the Singer 31-20 sewing machine?

Needles for Machine 31-20 are of Class and Variety 16 x 87 when used on a power table, and 16 x 73 when used on a treadle stand. They are available in sizes 9, 11, 13, 14, 16, 17, 18, 19, 21, 22 and 23. The size of the needle should be determined by the size of the thread, which must pass freely through the eye of the needle. Rough or uneven thread, or thread that passes with difficulty through the eye of the needle, will interfere with the successful use of the machine. Only SINGER Needles should be used in SINGER Machines, and they are marked with the Company's Trade Mark "SIMANCO." Needles in containers marked "FOR SINGER MACHINES" are not SINGER made needles. For more information, see page 3 of the manual.

Was this helpful? How do I adjust the stitch length on the Singer 31-20 sewing machine?

The length of stitch is regulated by the thumb screw (A, Fig. 2, page 4) in the slot on the front of the upright part of the arm. To lengthen the stitch, loosen this thumb screw and move it downwardly. To shorten the stitch, loosen this thumb screw and move it upwardly. When the desired length of stitch has been obtained, tighten the thumb screw (A).

Was this helpful? What is the recommended maintenance schedule for the Singer 31-20 sewing machine? When in continuous use, the machine should be oiled at least twice each day. Was this helpful? How do I properly install the bobbin case on the Singer 31-20 sewing machine?

After threading, take the bobbin case by the latch, holding it between the thumb and forefinger of the left hand. Place the bobbin case on the centre stud of the shuttle body with the position finger opposite the notch at the top of the shuttle race. Release the latch and press the bobbin case back until the latch catches the groove near the end of the stud. Allow about two inches of thread to hang free. For more information, see page 6 of the manual.

Was this helpful? What types of fabric thicknesses can the Singer 31-20 sewing machine handle? Was this helpful? Are there specific lubricants or oils recommended for the Singer 31-20 sewing machine?

TYPE B: MANUFACTURING MACHINE OIL, HEAVY GRADE.
TYPE D: MANUFACTURING MACHINE OIL, STAINLESS, HEAVY GRADE (when a stainless oil is desired).

Other Singer lubricants include:

TYPE E: STAINLESS THREAD LUBRICANT for lubricating needle thread.
TYPE F: MOTOR OIL for oil lubricated motors and plain bearings in power tables and transmitters.
GEAR LUBRICANT: A specially prepared grease for gear lubrication on manufacturing sewing machines.
BALL BEARING LUBRICANT: A pure grease specially designed for the lubrication of ball bearings and ball thrust bearings of motors and electric transmitters, and ball bearing hangers of power tables, etc.

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