Can somebody help me make a spinning blade trap, like in HL2 in Ravenholm

I’ve seen a lot of movies made by gmod, and there are blades or other props connected to a spinning prop by rope, and I have been wanting to make one, but I don’t know how.

An example of where it happens is in this video (I think it shows it four times) http://www.youtube.com/watch?v=87fgeOfik7U#movie_player

Wheel tool -> set to a high torque -> select blade model -> done

Just a weld

[editline]03:00AM[/editline]

To another spinning prop that is. Rope is there to look nice.

How could I be so stupid? (well, that’s me)
Thanks a lot =D