Thread

The Bernina Sewing Guide for my 830 recommends a mercerised sewing thread (3ply) in a size 50 for use with fine and medium needles (70 or 80). I typically use Gutermann polyester sew all. So far I can not find definitive documentation that this thread is most compatible with my sewing machine. The Gutermann website does not provide weight specifications for the home sewing threads.