What I'm trying to do is this.  I am running a motion study of rod moving back and forth inside a valve block using an isometric view.  After a few seconds I have the valve block transparancy turned on so I can see the rod moving.  What I'd like to do is after a few more seconds, I want the rod to go from a full version of the rod to a cross section. It has some ports that I want to show in relation to the ports in the valve block.  Is this possible and if so, can someone point me in the right direction for doing this??  I know I can create a copy of the rod and cut it in half, add it to the assembly and then hide the non-cut version at the time required but I'd prefer not to go in this direction.  Thanks.