I am finally getting around to posting the next chapter.  So the next step was figuring out how to join the sections so that they were both secure but also easy to assemble and disassemble. The original design was to use outside rings to join the segments. I experimented with making these rings using my CNC machine.  I started by making a couple of prototypes out of Doug fir. 

 

The problem is that they need to be longer than I can do on my CNC so I would have to make them in sections and glue them together.  I ultimately decided that it would be better to make them on my lathe.    So I started turning tubes of various sizes. 

 

These were all made from Bradford pear I had laying around.   After milling blanks from Bradford pear logs, I basically turned it round and mounted it in a chuck so that I could use Forstner bits to drill out the centers  The largest rings were much bigger than my largest Forstner bit so I had to finish the hollowing by hand and turn it to size to fit  the ends of each  section.

This ring has a bark inclusion that I stabilized with some brown CA.