Breaking thread and under thread is loose

Is the top thread making a thread mess under the fabric? That usually means the top tension is too loose or the thread is not seated in the tension disk.

Remove the top thread from the machine.
ALWAYS RAISE the presser foot and rethread from the beginning.
Set the top tension at the midpoint and test your machine. Then adjust the tension until the two threads meet in the middle of the fabric.

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Install a brand new needle. Make sure you are using thread and needle that are compatible with the fabric you are sewing.

Change the type of thread you are using. Old or bargain bin threads will frequently cause problems.

Clean the tension disks to make sure there is nothing stuck that is preventing the thread from feeding.

Remove all the thread and re-thread from the beginning. FIRST raise the presser foot so the tension disks will allow the thread to seat properly. (Consult your owner's manual.) Make sure you are threading everything in the proper sequence and not missing any steps.

Set the upper tension at the halfway point between the high and low number.

Stitch a test on a piece of your scrap fabric from your project.

The ideal tension is when the upper thread and bobbin thread meet in the middle of the fabric. If the bobbin thread is appearing at the top of the fabric, your upper tension is too tight and needs to be loosened. If the upper thread is appearing under the fabric or forming a loopy mess, the upper thread is too loose.

Keep adjusting and testing until the tension appears correct.

If the thread continues to break, then there may be a burr that is catching the thread and breaking it. Or the timing could be off. Take it for service.

http://www.schmetzneedles.com/all-about-needles/

http://www.sewingandcraftcorner.com/why-does-my-thread-keep-breaking-while-i-sew/

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Bobbin tension is one of the biggest problems most sewing machine operators have. Check information sent for assistance on this.

The top thread breaks

1. the needle thread is not threaded properly

2. The needle thread tension is to tight

3. The needle is bent or blunt

4. The needle is incorrectly inserted

5. The needle thread & the bobbin thread are not set under the presser foot when starting to sew

6. the threads were not drawn to the rear after sewing

7. The thread is either to heavy or to fine for the needle

8. Try a different spool or cone of thread

This was happening to me when I put new needle and I just checked tension on bobbin thread and for some reason it was to tight, adjusted to make looser as shown in manual and the tread stopped breaking.

The needle thread breaks
1. the needle thread is not threaded properly
2. The needle thread tension is to tight
3. The needle is bent or blunt
4. The needle is incorrectly inserted
5. The needle thread & the bobbin thread are not set under the presser foot when starting to sew
6. the threads were not drawn to the rear after sewing
7. The thread is either to heavy or to fine for the needle

My experiences with thread breaking with machine on a quilting frame make me look at the upper tension being set too high, the needle being worn or movement of the machine is too fast. Reduce the upper tension first, then sew in straight lines at first. See if you can sew slowly, in straight lines and reduce the upper tension until the thread stops breaking. If so, try some 1-2 inch circles, again going slowly. If the needle thread is pulling to the back, you will need to increase the upper tension again until the stitches meet in the middle of the fabric. If you can't locate a balanced spot where the needle thread is not pulling to the back side and thread doesn't break, try taking the machine off of the frame and sewing on a table. If it won't sew this way, it needs some professional help. If it does, you will probably save a lot of time taking it in for service, making sure to explain to the repair center that you have problems on a quilting frame, not while sewing normally. When the machine is adjusted to sew normally on a table and you move it to the frame, you will probably need to reduce the tension by 1-2 complete turns of the tension knob.

If the thread breaks at the needle and is feeding smoothly from the spool, you may have the tension too high. It is impossible to say what the setting should be because the knob rotates all the way around several times. Loosen it off until you see needle thread pull to the back of the quilt, then tighten until it just balances the interlocking of the stitch in the fabric. Test with little swirls, that's most likely to pull needle thread to back.Also, check that the needle is properly installed and that the hook to needle timing and clearance are good.Nesting of thread underneath usually happens if the foot lifter is left up or the tread is not fully in the disks of the tension unit.

this is a known issue with the pfaff.....i have just bought the machine and it has thread uptake issues...thread tension issues and it comes unthreaded by itself often...leaving globs of thread on the bottom stuck in the feed dogs and under the throat plate.....then the stitches are not properly balanced because the tension gets too loose on the bobbin thread....very disappointed to find out it is a known issue with all the viking husqvarna made machines...which are pfaff, janome and viking.....sux.

My friend and I both have the Juki 98Q but on different frames - we were both having problems (needles breaking, thread getting tangled) we removed the thin metal thing inside the bobbin case and have had no problems since (over a year now!).