40 wt is way to thick for piecing and rayon thread is mostly used for machine embroidery. Aurifil is 50 wt 2 ply so it's thinner the 50 wt 3 ply which most 50 wt thread is. You have to know the ply not only the weight. Then there is needle size for thread size. One size needle does not fit all threads. Needles not only have size but type. Superior threads has thread and needle education on their website. I like Masterpiece or Aurifil for piecing. I buy pre wound bobbins from Superior, cotton and poly.

I also use Sew Fine for both piecing and long arm quilting., I use it on top and bottom. I also use Polyestor thread from Connecting Threads for piecing.

Interesting discussion (I almost said "interesting thread). I'm starting to wonder if thread selection isn't kind of like fishing lure selection. It's been said for years that the huge selection of fishing lures wasn't to catch fish........ but to catch fisherman! LOL

Jim

Newbie and Learning...
 

Hello, I am new here and to sewing quilts. I was searching for thread and discovered Superior; I was wondering the same thing as KBarm...I did order some basic colors to get started, in the Bottom Line, and also the Sew Creative line. I have been using Dual Duty on my old Singer . I wanted something less linty. Will be following and learning from everyone.

I routinely use 50 wt 3 ply So Fine for all my piecing. For quilting, I use Bottom Line in prewounds (aka Super Bobs) and whatever I feel like on top. My machine takes whatever I throw at it - So Fine, King Tut, Superior and a Yenmet metallics, Floriani, Isacord, YLI, Guterman, Aurifil, etc. Learn to adjust your tension and your world expands.