I am creating an inventor model of the Stewart Platform and I have decided to employ the spherical joint for the same. But being an amateur, I don't know how to exactly make a spherical ball socket joint. Help!

Draw a semi circle outline (if you had to cut the sphere in half) making sure it is constrained around a center line and instead of extruding it revolve it.Good luck.

You can do this by following the advice above to create a sphere.  Then use the same method (in subtraction) to carve a hole in the mating part.  Use a standard constraint on the two curved surfaces.I don't have the time upload everything to the web etc.But you can contact me at www.tarfman.net and I'll forward you a couple of files to work on.