Contacts of differents bodies during simulation

[ajayz]

Hi all,
I'm doing a simulation of a nucleolus with couple of forces involved and One thing I see during the simulation is that the different bodies, instead of colliding, go through one another. And I'd like for the bodies to collide. I already change the settings in solver to contacts , but it doesn't help....
Another question is how can we add a constraint to an angle. For instance given two cylinder connected with a cardan joint, I want to limit the angle of rotation of one cylinder.

So pluuuuuueeeaaase everyone... It would be great If you can help me.

Katy.