Hi Jamie,
Welcome to the forum!!
For a mechanical system like this first, let’s work out a couple of knowns. Finding the RPM will be easy as 1 rotation raises the screen 2mm. Giving us 1500 RPM.
The torque required is a bit more involved as we get a bit of mechanical advantage. With the rod, you are using we get about a 1:20 reduction from the pitch. Then again factoring in the radius of the rod to get the torque required of around 0.7kg/cm, all of this doesn’t factor in any frictions or losses. A value of 2 or 3 kg/cm would be a safe bet here!
Controlling the motors is a whole other can of worms as with selecting a controller (there’s an active post here: Pololu Tic T834 USB Multi-Interface Stepper Motor Controller (Connectors Soldered) (POLOLU-3132))
Let us know if you have any questions!
Liam.
