I'm glad to see that you are at it again.  I've also got the itch to make some patio chairs of similar design but do not really know where to start.  I will be following along for inspiration.  

BTW,  I see that you are using Vcarve for your CNC.  Have you tried using the tiling feature for machining pieces too large for your machine.  I've used it a few times by sliding the pieces through the Y axis.  That might allow you to machine the long sections from a single piece of material rather than having to join them.  The key is creating a means to slide the piece precisely between tiled sections.  I usually machine alignment holes in my CNC spoil board or a fixture that is clamped down to the bed and use corresponding alignment holes in the waste areas of the material.  

--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.