Unresolved Transform stepper motor

Hi! I'm completely new to the topic and I apologize for asking dummy questions,
but it would be great if you could help me anyway: I have a nema23- motor with a smooth captive shaft and I would need to transform it into a non-captive motor, so that I can insert a leadscrew in the inside... Is there a way I could do it without needing to buy a new motor? What pieces do I need ?

Thank you very much for the help!

 

There are various designs of shaft couplers with a different diameter going in & out. Do you know the size of both shafts?

 

The internal diameter of the rotor (as the outer diameter of the shaft that I have now) is 0,8 cm, and I'd like to insert a leadscrew with approximately the same diameter

 

This is what you're looking for:

 

Thank you, but I was actually looking for a screw, that goes through the motor, like this one in the picture.
If I understand it right, the coupler you showed me is for external linear actuators.

 

That's a threaded rod.