As May rolled around and the weather grew nicer, I could finally get to work in earnest making the timber wall frames. I was planning for a barn raising sometime in later June, hopefully getting a dozen or so friends and family to help me set the wall frames up and to wrangle the 8 rafters for the roof.
Through a co-worker who was tearing out her deck, I got a good pile of usuable 2×6 boards, some pressure-treated 4×4s, and some concrete footing blocks. I used the 4×4s and 2×6s to build a level framework on which to lay the logs out and be able to work with them more easily.
I did some research about what kind of joinery to use. I wasn’t terribly interested in using modern steel connections, so I cast about for more natural/traditional methods. From Simon Dale's site, I decided to go with half-lapped beams, because the idea of calculating 125-degree mortise angles for an octagon seemed a bit overwhelming. To secure the half-lap joints, I plan on using a central pin of rebar, drilled and driven vertically into the top of the post and through holes in the overlapping beam laps. That pin would also serve as a connection point for the rafters later on.
As a woodworker, my experience is mostly boxes and furniture (more of a joiner than a carpenter), so I figured a couple of half-laps were easy, right? Until I approached the work and it hit home was working with a tapering, round-ISH, irregular log was like! How would I get two co-planar surfaces nearly eight feet apart? It’s not like I could use a plane or even a square to get a true reference face! What to do?
Lucikly, it was Roy Underhill to the rescue (duh, right?). One of his videos showed how to use a chalk line and a level to square a log for hewing, and the technique worked perfectly for making the half-laps match at opposite ends. Once that once done, the next challenge was to make the diagonal braces. These I wanted to do with mortise-and-tenon joints that would be pegged and wedged. Again, it was challenging to figure out how to cut precise joints from a round branch, but that problem was solved by building a square box jig, open on the ends, with one end cut in a 45-degree angle. As I write this, I don’t have a picture of it, but I’ll try to include one later. At any rate, it worked, and the joints came out looking like this:
And here’s how the first henge/wallframe turned out:
It took a long time to make, but luckily I only needed four of them, since the other four walls of the octagon would be created by the addition of the overhead beam.