I'm a true beginner when it comes to long arming and choosing thread (just bought my long arm in October). I bought a bunch of Glide poly thread 40 wt. on line. When I tried quilting with it I had a devil of a time with breakage. Thru trial and error I found its doing the best when I use a 50 wt. cotton in the bobbin. Because I'm using a Juki 2200 QVP the repairman said it was best to always use a size 18 needle and that he would have to make special adjustments to set it up to use a size 16. Now I wish I had bought some 50 wt. colors in cotton because what I'm quilting now would look better in a heavier thread.