Started machine quilting; first pass went just fine, rolled up quilted portion, then started machine again but the bobbin thread broke and continues to break. Took out bobbin, reset it in case, etc. N

The PC8500 does not do free motion well because of its tension design, it is not you.It was one of he earlier machines to set tension by the thickness of the fabric. If you really want to do free motion then it is time for a different machine.

Tension for stitching a quilt sandwich is tricky. It helps if you use the same color for top and bobbin thread,. If your quilting thread is not the same weight (either heavier or lighter) than thread used for regular sewing, then the bobbin tension may need to be adjusted. My quilting thread is lighter weight so I have a separate bobbin case whos tension has been adjusted specifically for quilting. The goal is have both threads meet in the middle of the sandwich. If the top thread is showing under the sandwich, you probably need to tighten the top tension so it will pull the bobbin thread up into the sandwich. Do the reverse if the bobbin thread shows on top.

It may also make a difference by changing the type and size needle. I tend to prefer a top-stitch needle. An embroidery or microtex may also work for you.

Machine Quilting Thread and Tension

Tension troubles on your quilting machine Try these tricks

5 Free Motion Quilting Problems and How to Fix Them

Free motion quilting is a finicky function, much more than most other sewing. Since you are getting loops on the back of the fabric, try increasing the upper thread tension. Tension causes the top and bobbin threads to pull against each other. If the pull is not equal, the threads will be pulled to one side or the other.

If you continue to experience looping under the fabric, it could be that the top thread is not fully seated in the tension disk. Try this:

Remove the top thread completely from the machine.
Be sure to install a brand new sharp needle.
ALWAYS RAISE the presser foot and rethread from the beginning.
Retest your machine.

However, if you don't find a fix, $25 for the special bobbin holder is probably a reasonable cost if it takes care of the problem. The reviews seem to be good:

http://www.sewvacdirect.com/janome-bobbin-case-for-free-motion-quilting-fits-models-mc14000-mc6500p-mc6600p-mc11000-mc7700-mc12000-and-more/

https://thequiltshow.com/forum/domestic-sewing-machines/120-janome-mc6600p
"Yesterday I bought a new free motion quilting foot and a bobbinholder (for free motion) for my MC Janome 6600P. I have been quilting all day, and belive you me it is a greate investment!!! :lol: :lol: Its like sewing on butter :lol: :shock:

Free motion Quilting Foot: part no.: 200-442-004 (MC6600P and MC11000)

Bobbin Holder (for free quilting and hand-look quiltstitch): part no.: 200-445-007 (MC 6600P, MC11000 and MC6500)

Bet you would love to have those too if you are doing a lot of free motion! The quiltfoot you can adjust so it works perfectly on your quilt!
:lol: :D :wink: I am sooooo happy!!!!"


https://www.getasquiltingstudio.com/2012/01/free-motion-quilting-tips-ii.html

LOOPS Tension or Speed

Free Motion Quilting Tension Problems

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Quilting is a bit more finicky than regular sewing. Be sure to ALWAYS RAISE the presser foot when threading the top thread. FWIW, I use a separate bobbin case for FMQ that I have tightened the tension to keep the bobbin thread from coming to the top of the sandwich, but I tend to use a finer thread for quilting so adjusting the bobbin takes care of it. In your case, however, it sounds like the top thread is staying under the fabric. I would try tightening the top tension. Also, install a brand new needle--a top stitch, embroidery, or microtex needle seem to work well for me. Test well on a sandwich made of the same fabric and batting and get it adjusted well before sewing on your quilt. Sometimes sewing speed will affect stitches under the fabric, or even on top.

5 Free Motion Quilting Problems and How to Fix Them

Correcting Sewing Machine Tension for Free Motion Quilting NQC

LOOPS Tension or Speed

https://www.generations-quilt-patterns.com/machine-quilting-thread.html

https://www.generations-quilt-patterns.com/sewing-machine-tension.html

https://www.generations-quilt-patterns.com/machine-quilting-tension-problems.html

...

Adjust the tension the same way as sewing regular projects. You want the top and bobbin threads to meet in the middle of the quilt sandwich. When quilting, I use a lighter weight thread so I have a separate bobbin case whose tension has been tightened specifically for quilting. For other sewing projects using a standard thread weight, I use a bobbin case that is factory set and then adjust the top thread tension for each project.

TIP: A general rule of thumb is that if the stitch looks bad on the top it is the bottom tension.
If the stitch looks bad on the bottom it is the upper tension. The upper and lower threads play
tug of war with each other.
Tension
You need correct tension on the top and bottom threads, but you must also have correct tension on
the quilt held between the rails. You should have a small amount of "sag" in your fabric. This allows
enough movement of your quilt layers for the needle to penetrate and make good stitches.
Before you start making adjustments to your machine ask yourself, "What changed?" If your machine
was stitching great and all of a sudden it has loopies on the back or puckers, "What changed?" Did
you just change the bobbin? Did you just lift the take up rail? Did you lower the take up rail after
finishing your last quilt? Did you recently change the needle? Did you just roll the quilt?
If the take up rail with the quilted portion of your quilt is too high, it will result in poor stitch quality. You
need a finger tip space between the quilt and the machine bed. Higher will result in poor stitch
quality, too low and the quilt will create a drag on your machine's movement.
Look at your bobbin, a sloppy wound bobbin will not create a good stitch. Make sure that the threads
on the bobbin are snug and evenly wound. Check to see if there is a piece of lint in the bobbin case

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

This should be an easy fix, something is wrong with the upper threading. Take the thread off the machine, raise the presser foot up and rethread the machine, that should take care of it.

Try threading the machine with the presser foot up and see if the loops and snarls go away.........

When the foot is down during the threading, the tension control is closed and the thread cannot enter as it should.

No tension control of the top thread and the bobbin thread cannot connect for a proper stitch.

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!).