My tub's drain flange has had the little cross piece inside it broken out, which means I cannot screw a grid drain into it. Right now, it's totally open and an invitation for my toddler to drop stuff down. Not to mention lots of hair, etc.
I believe I need to replace the drain flange and put a grid drain on top of that (I want a grid drain like a shower instead of a typical tub stopper).
"Drain flange" terminology from this image.
I have measured the diameter across the drain at just under 2" which I believe means a pipe thread size of 1.5" (from http://www.plumbingsupply.com/pipethreadsizing.html). However, I thought I remember learning that drains may be either coarse or fine threaded.
Before removing existing drain flange, is there any way to know if it is coarse or fine threaded, or are all 1.5" drains the same as far as thread count goes? I want to be sure to order the correct part, whether I do the work or hire a plumber.