Originally Posted by BellaBoo

The needle size depends on your thread size. You have to know the weight and ply of the thread and then select the right needle size. I use Superior Organ Ttitanium coated Topstitch needles for piecing and machine quilting. The titanium needles stay sharp about 5x longer then regular needles. I rarely have thread or tension issues on any of my machines.

Here is list of general needle and thread matches:

For Size #70/10 - #100, 60 wt., & MonoPoly.
For Size #80/12 - #50 (50 wt.) threads.
For Size #90/14 - #40 (40 wt.) threads.
For Size #100/16 - #30 (30 wt.) threads and thicker.