What type of thread are you using? Is it a quilting thread? a quilting thread is a thick thread I believe meant for hand quilting I made that mistake a few months ago it will not work on our machines.

When I first got my Juki I had that problem, I called a machine repair center and they told me the Juki's like the same thread on the top and bobbin. I was using a prewound bobbin and changed and have not had a problem since.

My Juki doesn't like thick thread, but I use pre-wound bobbins all the time with no problem.

my juki is on a quilting frame and usually pretty reliable..it sat all summer and this fall when I started quilting with it I was getting loopies on the botton. Had to re-adjust the bobbin. NOW WHY would that change over the summer...never had a problem before but now she is cooperating very well again. They are such nice machines..would love to take her to retreats but its such a pain unhooking etc and she is very heavy. Good LUck. BYW I only use 2 holes on the side and oil after every second quilt...sometimes I think too much is not good either

I bought a used Juki TL-98Q on the a Grace GMQ Pro frame about a year ago. Unfortunately, I've never gotten the machine to work correctly. I've had it serviced, but it still has the same problems. (Too long ago to take it back and have no receipt.) If the thread is not breaking on top, it's clumping on the bottom. I've taken it off the frame and used it as a regular sewing machine, but I have the same problems. (I wasn't sure if it was a problem with the machine or the quilt/frame.) I'm about ready to give up, but I see that nearly everyone here that has this machine loves it. I love it too, until I feed a new piece of fabric in and it clumps/breaks the thread. Any ideas?

stupid question but are you absolute sure it is threaded right? is the bobbin going the right way..just some things I would check. its always something simple...

I had the same problem. This is what my tension is on and it works great. Hope this helps!

Guess I better get my book out and double check. Thanks for the ideas.

I have wondered also why the tension woulld change once it is set right. I love my machine but that is one thing that bugs me. It can make a beautiful stitch IF the tension is set correctly.

The quilting thread may require a lighter tension than the Aurifil.

With the constantly breaking thread, I'd probably suspect the needle, first.

The thread should lie smoothly in the groove on the needle shank without a lot of extra room and without overstuffing the groove - and it should pass easily through the eye of the needle without squeezing it.

The groove protects the thread from abrasion as it's being pulled down into the fabric - and the same little section of thread may saw back and forth through the needle many times before it's deposited in the seam. :)

If the needle doesn't fit the thread to protect and guide it, you're going to have broken thread and needles and skipped stitches.

Try a size larger, then two sizes larger - or even the same size but in a large-eye type, like for top-stitching or metallics - and see if that doesn't help.

If you're already using a large needle and you've gone down to a finer thread, the eye may be too big, allowing the thread to whip around and catch on the point or otherwise tangle and break. Try a size smaller, then two sizes smaller.

I hope you can get it working well for you! :)