Cathy, I use a Superior Topstitch needle size 80 with this combination of thread. I use stitch #1326 on my Bernina 765/770--it is designed for piecing with two layers of quilting cotton. Length is 2.0, tension 4.0.

There have been many mentions by Alex regarding using 60 wt thread for piecing with 80 wt in the bobbin. Does the tension need to be adjusted and do you need to use a smaller needle? I use Aurafil 50wt for piecing and quilting top and bottom and an 80 needle. I have a Bernina 570 QE.

Thanks in advance.

Cathy Jenet