I have used cotton poly and rayon for my mahcine it likes 2 of the 3 It hates the rayon nothing I could change would improve the stitching and the breakage of the threads. My Tin Lizzie18 loves the poly thread used mostly in embrodery machines. it also quilts up nicely. cotton top and bobbin also works smoothly and looks great and as far as I know both have held up great.