Mechanics of automatic opening/closing of curtains. Any ideas?

Question

Python

That's the point
I decided to cut down a thing that will open / close the curtains. There are no problems with the electronic part. Stupidly Arduino (because I have it) will control the stepper.
But the question arose: how to implement the physical part? I sketched what the curtains look like:

Task: the stepper is spinning, SOMEONE converts the torque into a "pulling" one, both curtains are assembled on different sides. If the stepper spins in the opposite direction, the reverse process occurs.
Can you help?

Answer 1

Knowing the finicky of PyQt, I think it's worth trying to move all executable functions to the second thread, leaving only the UI and signal handlers in the first. You have a cycle there, and he really doesn't like cycles in the main thread. Even if the problem is not solved, it will still be useful.

Answer 2

fishing line - there are 2 turns on the motor (so as not to get confused), on the other side there is a wheel - to tighten the fishing line, fix it through a spring (it is harder to make a motor with a spring). We get two fishing lines moving in different directions, we attach curtains to them from the center of the curtain.

Answer 3

IMHO stepper is not needed, a conventional motor will suffice. In fact, you need a ring of rope that the motor will turn, and one point of this ring will be at the end of the curtain.