The mystery of the uniform Eucalyptus stretch is partially  solved.  This picture shows the 13  1/2 inch piece of firewood from which my third chain was birthed. It stretched to 6 inches.

My fourth carving was from pine. in this one I was attempting to make a twisted flat-link chain… like the links used on a dog’s “choke-chain.” But as I started to separate the links, I realized that I needed 4 twisted columns… not the 2 that I had started with… so, I ended up with a spiral twisted column instead of links.

My second attempt at making a twisted link chain turned out a lot better, but still not what I had visualized. As can be seen in this picture, the links are indeed twisted, but they form a round-link chain, not the flat-link chain that I expected.
Even as I write this, it dawns on me that if I want a flat-link chain I’ll have to start with a flat piece of wood! I’ll try again.

This turned out to be a VERY difficult challenge! I had a hard time wrapping my mind around this problem of visualizing how this should proceed, so after making a few futile drawings, I just started carving. One link turned out a little different than the other and there wasn’t quite enough twist in either of them, but it wasn’t too bad.

In this photo, the “chain” is beside the original block from which it was taken, to show how much it was stretched.