Try sewing but bottom thread on fabric is crumpING UP

Looping on wrong (bottom) side of fabric is almost always insufficient tension of top thread.

The fabric appears to be multiple layers high density so it will take a higher than typical tension setting.

You can easily verify it is top thread looping on bottom by using a different color top thread. Using a different color top thread will also aid in setting the proper tension as you'll be able to see bottom thread eventually come to top side as you increase tension. Then reduce tension until stitch returns to center of fabric layer.

It sounds like maybe the bobbin tension is too tight. It is pulling the top thread down to the bottom of the fabric. If you tighten the top tension it causes the fabric to pucker. If you loosen the top tension, more of the top thread will show on the bottom. Correct tension is when the top and bobbin threads meet in the middle of the fabric.

Understanding Thread Tension on Your Sewing Machine

Both tensions are preset at the factory. Normally, the bobbin tension is the last one to adjust. Most often tension adjustments are made to the top thread. The factory standard setting for the upper thread is the midway point between the high & low numbers, however, each machine is different and may need slight readjustment.

The tensions are correct when both, the upper and bobbin, threads meet in the middle of the fabric. Tension is not static. Differing fabric weights, thread, or needle sizes may necessitate a change to tension. Lighter weight fabrics like chiffon will require a different tension setting than heavy fabrics like denim. Always test first on scraps of the fabric you plan to sew. Get the tension set the way you want it before you begin sewing your project.


Learn the Ins and Outs of Troubleshooting Sewing Machine Tension

Adjusting Sewing Machine Tension to Prevent Problems

How to Adjust Tension Sewing Machine

Hello, If the thread is loose on the bottom then it is the tension on the top. If the thread is loose on top then it is underneath.

first let's deal with the needle becoming unthreaded, Keeping the needle threaded is easy, always keep thread tails of 3 to 6 inches on the top thread & bobbin at all times, & make sure the thread tail are pulled behind the needle before you start to sew,, this will ensure that the thread will not come out of the needle when you start to sew.

you mention the fabric is thin,, do you have a needle that's right for the fabric your sewing?
thin fabric needs a different needle than blue jeans fabric, check your top tension & see what the setting is on, usually 3 to 5 is good.

when the needle & thread are right for the fabric then the sewing is good.

also clean under the needle plate & bobbin area for loose threads or lint

also it's a possibility that the machine could be out of time & would need to be serviced by a sewing machine repair shop-as they have the tools for the job

You need to fine-tune the tension. The instructions I'm going to give you will work with any sewing machine and can be repeated for any type of fabric you sew in the future where this happens. Use a scrap of the material you're sewing with that's a few inches long and a couple of inches wide. Also, it helps if you use different color threads in the top and the bobbin thread.

Thread your machine with the presser foot UP. The disks that control the tension (threadgoes through them) are tightened up if the foot is down. Change the machine tension with the presser foot DOWN.Because the disks won't be engaged (see above) if the foot is up, the diskswon't move. Start at the middle setting, 3. Go up to tighten, decrease toloosen. Each machine is different, even 2 different machines of the same model.The best thing to do is start at 3 and use a different color in the top andbobbin thread so you can easily see what changes to the tension do to yourstitches. Now use a straight stitch a sew 3 or so inches. Take a lookat the top and bottom of the fabric. You don't want to see any (or at least notmuch) of the other color showing from the other side. Loops on the bottom of the fabric means you need to tighten(increase) your top tension. If you're stitches on the bottom are causingpuckering, then you need to loosen you're top tension. For the most part, youreally don't want to touch your bobbin tension-leave that to a repairtechnician. The factory setting shouldn't be touched except by someone whoreally knows what they're doing. Keep sewing a few inches at a time until you have the resultsyou want. Now you're tension is where you need it!

Check the ovious things first make sure you needle isnt broken... then make sure there isnt any thread twisted inside your bobin housing. make sure bobin is inserted correctly if those things dont help it could be an issue of timing in your machine... I work as an embroidery operator in a factory setting and those things usually help..

The bottom thread is the bobbin thread and it is suppose the pull the top thread slightly to the bottom/center of the layers of fabric.

Try a lower tension setting and a tear-away stabilizer or sheet of printer paper under the fabric to see if this will help hold the top thread down into the fabric.

Be sure when you are threading the top thread that you ALWAYS RAISE the presser foot. This releases the tension disk and allows the thread to seat properly.

Have you gone back and re-tested on your test fabric? Does it work okay on the test fabric? If so, then there's a suspicion that it has something to do with the fabric, needle & thread of your project. Is your project fabric very dense, heavy... Are you using a stabilizer? A hoop--is it taut, not stretched? Make sure the fabric is not trampolining. Could be an incompatibility. The needle & thread may be having difficulty piercing the fabric. Try a different weight needle, perhaps a microtex or embroidery needle.

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.