did you think "what to hell's the Irishman at?"
PB, are you psychic?
Seriously, though, semolina is, imo, kind of advanced pizzamaking. It's definitely something worth playing around with, but I'd wait until you've mastered a non semolina pie.
.085 is the thickness of the crust. Imagine taking a ruler, placing it next to a cross section, and taking the measurement. That's a simplification of what .085 represents. The lower the number the thinner the crust, the higher the number the thicker the crust.
The thickness factor dictates how much dough you'll need to use for a crust of a given diameter. As long as you follow the formula and stretch the pizza to the given size, the thickness factor will be whatever you plugged into the calculator. The semolina probably threw a wrench into the thickness equation, but, next time, see if you can follow the formula and stretch it to 12".
It's also very helpful to stretch the dough the right way. Here's a good video (ignore the rolling pin stuff)
One of the most important stretches is the edge stretch. Take a look at 1:30 to 1:50. The edge stretch is critical so that you don't end up with a bowl shaped skin.
Here's what it looks like if you've been doing it for most of your life:
(edge stretch from 00:21 to 00:27)