I use metallic threads in an upright position; Metallic, Metafil, or Metallica needles size 90/14 (they all have a longer, smoother eye, but I prefer Schmetz); tension at 2 or 3; and stitch length at 2.5 to 3. Metallic needles are smoother than topstitch needles, thus reducing the chances of breaking even further. Once I settled on these settings, they have worked for me perfectly ever since.
