To start building the lower retaining wall, I needed to have two of my wall posts in place as the outer anchor points. I quickly realized that I couldn’t just drop a post in a hole: I needed to build the whole henge and install it as a unit. Why? Because of the mortise-and-tenon diagonal braces, I had to make sure that the mortise was the right height and angle to mate with the overhead beam and its adjoining post. Even though timber framing doesn’t have to be to the thousandth-level tolerances we expect when we make furniture, imagine the problems that even a 1/4” misalignment of the post would cause.
I also dropped in a few short posts for support and to provide attachment points for the wall planks. Then I shoveled in the gravel and earth to backfill it. (Are we having fun yet?) After finishing the lower wall, creating the postholes for the upper wall holes was now easy, so I brought up my first wall frame/henge, and cemented it into place:
To permanently lock the braces into place, I pegged the tenon into the mortises. I made the pegs from the smaller brances of the maples I had cut down, creating them by using a 5/8” rounder plane (like a pencial sharpener on steroids). These had been drying for months now; the idea was to to use dry pegs in green timbers, so that as the timbers dry and shrink (but the pegs don’t) the braces would be locked ever tighter into place. After the pegs were pounded through, they were further secured from both sides with wedges I made from some scrap oak.
Here’s a larger detail of the connections:
Now the woodworking takes focus as I churn out braces, posts, and beams to make the rest of the henges…