Physics Problem

I am trying to create a see-saw in unity by using Unity physics but I am not able to get a proper balance. I used Rigidbody, FixedJoint, and HingeJoint to make it possible. I attached a video which shows you all the properties and behavior I am getting.
Video Link :

I don't know what I am doing wrong any help is appreciated.

Here, is the question link which I asked on StackOverflow which is more descripted.