You also need to check the height of your take-up rail. You should be able to slide your fingers between the machine bed and the rolled-up quilt. Too much space and you will break thread every time. Not enough space and you'll break thread and needle.

Darren

I have the viking long arm 18x8 and when i first started i had a lot of thread break but it was all from the tension. I worked on fixing both bobbin and top tension and then started working like a charm.