The thread keeps bursting after a few stitches. I've tried adjusting upper & bottom tensions,changing the needle, trying it with different fabrics, but nothing seems to work. What do I do?

First, be sure you are using a brand-new needle and that the needle, thread, and fabric are compatible.
All About Needles

When you thread the upper thread, be sure the presser foot is ALWAYS RAISED so the thread will seat properly in the tension disk. Also, confirm that the machine thread pathway is correct.

Remember that when fabric types/weights are changed, the needle/thread should be changed accordingly. (Needles should be changed often to attain the best sewing experience and minimize unnecessary frustration.) The tension may also need to adjusted. Tension is not static. It should be adjusted to fit the project being sewn. Unless one continuously sews with the same fabric, thread, and needle type would the tension adjustment remain at the same setting, but machines do change over time so a tension setting that worked last year may not look the same this year.

The factory standard tension setting is the midway point between the high & low numbers. However, please understand that machines vary and that sometimes this standard setting may change with time and use. The midway point should only be the beginning point and is most likely suitable for medium-weight fabric. Also, usually the bobbin tension does not require frequent adjustments unless a particularly heavy- or light-weight thread is used in the bobbin--sometimes the bobbin tension will get out of whack requiring adjustment (consult the owner's manual or search the internet for instructions for adjusting bobbin tension). In the majority of cases, the tension adjustment is made to the top thread.

Test your straight stitch on your fabric (may be helpful to use a different color thread in the bobbin so it is easier to see any tension issues). If the bobbin thread is popping up to the top of the fabric, loosen the upper thread tension. If the upper thread is looping or showing on the bottom of the fabric, tighten the upper tension. Keep adjusting until the upper and bobbin threads meet in the middle of the fabric.

FWIW, the same process would be used for zig-zag stitching. Just make sure that the tension is not too tight or it will cause the fabric to pucker (or tunnel).

...

First thing to do: install a brand new needle and clean the lint/dust from the feed dogs and bobbin area. Make sure you are using the right needle and thread for the fabric being sewn.

All About Needles

Second thing: remove all the thread from the machine. RAISE the presser foot and rethread from the beginning making sure that it is threaded correctly through every thread guide (consult the owner's manual). And verify that the bobbin is loaded and threaded in the bobbincase properly.

AVOID using old, fuzzy, and bargain bin threads.

Set the upper tension to the midway point between the high & low number (this is the factory standard although every machine may slightly differ). Now perform a new stitch test.

If the upper thread is creating a thread mess under the fabric, the upper tension is too loose. Tighten it.

If the bobbin thread is coming up to the top of the fabric, loosen the upper thread and retest. Sometimes the upper thread tension is not enough to prevent the bobbin thread from coming up. In that case, the bobbin tension may need to be tightened. (Search the internet for instructions for adjusting the bobbin tension. NOTE: bobbin tension adjustments should be done in micro-increments as a small adjustment will make a big difference in the result. Be sure to test after each adjustment.)

The tension is correct when the upper thread and bobbin thread meet and cross in the middle of the fabric. This will change whenever fabric, needle & thread are changed, so a sewist needs to be comfortable with regularly making upper thread adjustments.

One other thing to try is pull the bobbin thread up through the fabric before stitching and gently holding the thread tails when taking the first couple of stitches.

https://www.youtube.com/watch?v=caPzulMMlMU

...

try a new needle

try adjusting the top thread tension to see if that helps the bottom loopy stitch

Make sure you raise the presser foot BEFORE threading the upper thread so it will seat properly in the tension disk.

The factory standard tension setting is the halfway point between the low & high numbers. Be sure you are using needle & thread that are compatible with each other and the fabric you are sewing.
All About Needles

Test your stitch on the fabric you are sewing. If the upper thread is showing on the bottom of the fabric, the upper tension is too loose. If the bobbin thread is showing on the top of the fabric, the upper tension is too tight.

Ideal tension is when both upper and bobbin threads meet in the middle of the fabric. The tension will need adjusting anytime you change fabric weight, needle size, and thread weight.

....

Is your bobbin threaded correctly? You should be able to pull out the thread slowly while feeling it very slightly holding back. It should not pull out easily or quickly.
Could be something wrong with your tensions, try adjusting the upper tension first by starting at the middle setting and working gradually higher and then lower till you get a neat even stitch.

The standard factory tension setting is usually the midpoint between the high and low number. However, the upper tension is adjustable depending on your needle, thread & fabric. Thicker fabrics or thinner fabrics will need different tensions. To achieve the correct tension, test stitch and adjust the tension so the upper thread and bobbin thread meet in the middle of the fabric. If the upper thread is showing through on the bottom of the fabric, tighten the upper tension. If the bobbin thread is pulling to the top of the fabric, loosen the upper tension.

...

1. Make sure your needle is correct for the fabric. Go buy some good needles in several sizes. You'll need a 90 for jeans, rounded points for fine fabrics... get a few sizes. Your manual should provided you with clues to the right needle for the fabrics. (BTW... there really is no such thing as a Universal Needle... toss it.)

2. Re-read your manual and carefully follow the instructions on threading the bobbin and the upper thread...

3. Check your tension on the upper thread... it is too loose for the application. The tension on the bottom thread is handled by a spring on your bobbin case or race. If you do not have that threaded properly you'll have problems. Same with the direction the bobbin turns... have in it backwards... problems.

Barring all these things... It might be time for a qualified Singer repair person to look at it. Sadly Singer has seriously lowered it's standards in the last 20 years.

Hi. Loops on the underside of the fabric are generally caused by the upper tension being too loose. Use a size 12 needle, and size 50 thread with different colors in the upper thread and in the bobbin. Sew an inch or so, look at the stitch and adjust, tightening the tension just a bit at a time.

There's more detail in the tip I wrote about adjusting tension.

Hope this helps!

Robbie

Hello,
Here are a few things to try.

* Raise your feed dogs if your machine has this feature.

* When you start to sew a seam, hold the upper and bobbin thread tails. Hold them back and out of the way as you sew your first couple of stitches. This will keep them from getting caught in your machine.



* Your fabric may require a different needle. Generally, heavier fabrics require larger needles and thinner fabrics, smaller needles. You may also need a larger needle if you’re sewing through many layers of fabric. And make sure to use a ballpoint needle for knit fabrics and a sharp needle for woven (or a universal needle for either). And make sure your needle is appropriate for the type of thread you’re using.


* Adjust the pressure of your pressure foot, it may be too light for your fabric.


* If your upper thread and bobbin threads are different types, try using the same thread for both. And use a good quality, brand name thread.



* Change your needle plate. Try switching to a needle plate with a smaller hole (a straight stitch needle plate).


Important Note: If you change your needle plate, check to make sure your needle aligns perfectly with this smaller hole before starting to sew. A misaligned needle could hit the plate and break, which could be dangerous. And make sure to change your needle plate back for zigzag and other wide stitches.

Hope this helps.

If it was sewing correctly BEFORE the needle break...why did the needle break in the first place?...and what fixes did you make?
If it sewed properly...what changed?

Cut your upper thread close to the spool...make sure the presser foot is raised and pull the cut off thread section through/out of the machine from the needle area (sewing direction...do not pull the thread backwards!)

Clean out the bobbin area...remove any traces of lint or pieces of thread...look for any broken off needle pieces... brush the bobbin area out....then add a drop of sewing machine oil (but only if your manual says to oil that area).

Remove the needle plate to expose the feed dogs...brush/clean out that area too and add a drop of sewing machine oil...then secure the needle plate back on.
Replace the needle...do it again...yup...some needles arrive bad from the factory. Make sure the needle is inserted and positioned properly. Then thread the machine WITH the presser foot in raised position. (The thread needs to get seated into the upper tensions.)
..with the.presser foot down...thread the new needle.
Oh...and use the correct needle for the thread. (a universal 80/12 is standard).
Thread can cause issues too. Try a different bobbin, or maybe a different spool of thread to see if that makes a difference.