I don't know anything about your machine but I do know that my sewing machine does NOT like poly thread AT ALL!! If I put poly on and thread it up and start sewing, the thread will break, bunch up,you name it and it does it. So now the only thread I can use in my machine is the thread from Connecting Threads. Seems like sewing machines sometimes have a mind of their own. lol
Good Luck
Bev

when I change thread types (from poly to cotton), I need to adjust the tension settings each time. It sounds like the top tension is too tight. If you are getting loops on the back after loosening the top tension, then try loosening the bobbin tension. Also, poly thread will not harm your quilt. That's pretty much an old wive's tale. It's "generally" stronger than cotton, but it won't tear the fabric.

sorry I cant help. Good luck and God bless. Penny

Please PM me and let me know how it goes! I am ready to get started with mine.

I don't have a Grand Quilter but I have a 20 year old Design a quilt machine and I was ready to throw it out. Every thing I did seemed to make the thread break. I found a small bur on my throat plate will really cause a lot of grief. As I said my machine is old but you will learn all the quirks of it and love it later. I do use poly thread and it seems to do really good for years of washing , loving and dragging around by babies and adults.

Make sure that your quilt is not to tightly rolled. Even if you think it is loosen just a bit. I use all kinds of thread on my Handi Quilter. My favorite is Isacord embroidery thread. I mix threads too. Cotton on the top and poly in the bobbin. Let us know how you make out.

wesing, I feel for you, same thing happened to me. I have a different machine.
I know when I tried mine the first time I wanted to throw it away too.
I put two white flat sheets and batting together like I was making a quilt (so not to ruin a quilt). I did all the same things you probably did. Called everyone that I thought new anything about sewing. Nothing helped.
Finally after a few days, it just out of the blue, started sewing right.
No more thread breaks.
I believe we just need to learn to get our arm movement syncronized with the speed and stitch length. I don't know if this makes sense.
What I did was, begin with a slower speed on my machine and the movement of my arm and slowly increased the speed and movement of my arm to keep the stitches even in length
Practice, practice, practice.
I practiced different stitches until I quilted the whole piece, then used it for a mattress pad.
Good luck.