We finished cutting all of the tenons at the tops of the six posts. We also finished cutting the corresponding mortises into the three top plates!
With the help of Linnea, we moved on to cutting the tenons on the curved American elm beam. :-)
Since the elm beam is curved and not at all rectilinear, we needed to layout the joinery the old-fashioned way: by scribing. In order to do this, we cleared a large space on the cement workshop floor and marked a perfect rectangle in permanent marker. We then placed the south-facing Western Larch posts on the lines and moved the curved elm beam on top of them. Peter was able to then mark exactly where the curved elm beam will intersect both Larch posts.
We cut 2" thick tenons on the curved elm beam which will fully penetrate the Larch posts via a through-mortise. The bottoms of the elm tenons will be shouldered 3/4" into the posts. The elm tenon will pass a full 2" past the side of the post, which will look really, really nice.
Here is Peter planing the tenon with a small hand plane:
We stacked the beam atop the posts to double-check the cut. Looks good!
After the elm tenons have been fully cut, we can cut the corresponding through-mortices on the Larch posts. After that, its on to the struts and braces!