A need for large washers was mentioned in the last posting. I wasn’t satisfied with the washers available to me at the hardware store, so chose to make them myself. I had a pair of ancient gate hinges made of strap mild steel of the right width. I was planning to use 5/16” threaded rod for the connections, and so I drilled spaced holes 3/8” diameter along the centre of the hinge strap. I countersunk these holes to facilitate easier entry of the connecting rods. I then hacksawed the strap into square washers. I believe the square shape provides better thrust distribution for this application. Furthermore, it was a simple matter with a straight bit to rout out recesses in the post halves to house this shape.
The only way I know of to make precisely true central cores down long sections is to make the post in two halves, routing or dadoing a channel down the middle of the inside surface of each half. I did this, making a half inch diameter central channel. I modified this channel by hand carving to a hexagonal shape at the point where the collar nut would lie, so that it could never turn in the wood. Behind (downstream) of the nut I laid in a short section of dowel to stabilize the collar against longitudinal movement. The photo shows all this assembled, ready to be glued up. When gluing up I left a piece of threaded rod inserted into the collar nut so as to keep it perfectly aligned during the process. I oiled the rod in case of contact with the glue, and held the other end perfectly centred in the channel with a scrap of vinyl tubing.