kinect model + spring joint

Trying to add a spring joint and sphere to the example soldier’s hand in the kinect wrapper example(for example if you wanted to throw a grenade), but the sphere drags/contorts the arm completely(see attached image) - I tried making the arm components rigidbodies(had to make the hand a rigidbody to attach the spring joint), but not sure what steps needed to take to get the soldier body to act more solidly while still controlled via kinect.

Thanks
Jeremy

the sphere has mass = 1 and ‘use gravity’ checked - I can turn gravity off for the sphere to keep the arm from deforming, but initially was just trying to set a ‘break force’ on the spring joint as to try to simulate the ball letting go with a arm throw trajectory of some minimum force(like a whip motion breaking the hinge allowing the ball to arc in the general direction of the throw).

Got a different variation going without connecting to the original model components by just having a hidden anchor sphere(no gravity applied) update its position to that of the hand position with each NITE skeleton update. Next step is to change the spring joint’s breakforce to zero once the hand position is a certain threshold forward of the body - I think that should approximate something like a throw/toss if the sphere continues to follow the trajectory of the previous hand trajectory.