A "Lead Screw Joint" block has been added to the SimMechanics Second Generation in R2015a.
In order to implement a a screw joint in previous versions of SimMechanics a custom Simscape component can be created to model a screw joint.
For an example of such a component please see the attached file, including a screw_lib that is created by Simscape Language and a testScrew model.
The technique used in this model can be used to implement any type of constraint in SM2(SimMechanics Second Generation). The trick is that you sense the motion of the 2 DOF you want to constrain and feed to Motion actuator in Simscape. In Simscape, you sense the torque directly at those actuator and feed it back to SimMechanics. Between that, you define whatever constraint you need. For this to work, you need to add compliance, as I do with the spring and damper. A purely algebraic constraint will make the motion overdetermined.
Note that, the screw block in the model is created by Simscape language because SM2 does not have a screw block. If the you have SimDriveline, they may not need to do this, just use the screw block in that library.
