mechanism on forearm bones (HELP!!!)

Hi everyone, first time poster here. I'm in my final year of Mech Eng at
Imperial University and using Pro E for my dissertation. I have to
model the twist of the two bones that make up the forearm (radius and
ulna) and am having some serious difficulties doing so.

I'm
keeping it simple and just using two cylinders to represent the bones,
but its the twist motion and the mechanism that reflects the forearm that i'm having diffculty with.

The radius at the elbow just simply spins, but at the wrist end it orbits around the ulna.

Is this possible?

I've attached a diagram to help explain what I mean.



Any help would be greatly appreciated guys!









Edited by: saqademus

Possible...Yes!!!
How....need to model and assemble well....Providing motion comes next...

The motion is 180 degrees (ie palms outwards to palms inwards) so I
guess both radius and ulna will be able to rotate 180 degrees both ways.
The wrist also (makeshift wrist). But the elbow will not move.

the
radius part will spin on its central axis at the elbow joint (as it
does in ones arm) but the whole wrist will translate 180 degrees.

I hope that helps