I've been trying lots of variations on a theme to get my beams successfully installed. Cutting two deep grooves and then adding plywood "splines" with a strip of foundation sill insulation takes a fair bit of time. While I'm concerned with how slowly the walls are going up, I'm hopeful that in time I will become faster at it, and that perhaps with additional help from friends and family, it will also go more quickly.
The failure of using a chainsaw or router to cut the grooves for my splines led me to this crazy thought:
I'm quite certain it isn't generally recommended to have multiple blades on one circular saw. And I ended up finding that it didn't really make my cut appreciably wider.
Currently I have invested in a new circular saw that has better balance and power and fits the hand better:
Coupled with the new saw is a really cheap Canadian Tire saw blade (cheaper blades tend to have a wider kerf - or width of cut). I drop a chalk line on the beams, cut down the chalk line with one pass, then follow that cut with a second one in the same groove, but I guide it along the edge of the groove to try to double the width of it. This provides a good width for the spline. I find that with a rubber mallet in hand to tap along it, it works well. Even when the plywood cracks or actually breaks, I am able to continue tapping it into place successfully.
The "doubled up" groove is for the top of the beams. It holds the splines up nearly perpendicular to the beam, as well as ensuring they are most parallel to one another. I cut the grooves for the bottom beam slightly differently.
I realize that I will not likely be able to get a perfect fit from beam to beam. Many of my first beams had different twists and warps to them that made them difficult to be consistent with. At first I was trying to custom fit each beam, but now I think I have come to a better system.
The grooves on the bottom I cut similar to the ones on top, except that I tilt the circular saw blade at a 10 degree angle, and cut twice with that. The angle allows me to cut first on one side of the line, and then the second cut on the opposite side of the chalk line. This creates a deep V groove that is wide enough to catch the spline from the beam below and guide it into the new beam.
I had been trying to cut the corner joints customized for each beam at first. I found that this ended up compounding any imperfections in previous runs. Instead, I am currently cutting the corner joints at fixed places (4" in from the end of the beam, 3" wide). Then I twist or turn or shove the beams in and out and force them to fit the original plan. This isn't nearly as difficult as it would have been at first - because the beams are getting less and less twisted and warped as I go deeper into the pile. I believe the weight of the upper beams helped to keep the lower ones in place as they dried over the winter.
The corner notches haven't changed much in technique. I do a dry fit of the beam before I add the splines, then after I add them, and then I finally add the insulation and put the beam in place. Then I place a single screw in the notch to peg everything together.
At my openings, I also fasten the beams to one another by placing a 2.5" screw on each side of the beam, a little over an inch up from the bottom, three inches back from the opening, and angled down at 45 degrees so that it goes into the beam below. This screwhead should be covered by a 4" trim that I eventually plan for every opening.
I also check the beams for level before fastening them in place with the screws. Whatever end needs to be raised, I slide a small scrap of my 5mm plywood into. This is smaller than many natural gaps between the beams, and is not noticeable.
It's slow going, and frustrating when it isn't perfect. But that's the cost of tuition in my self-taught log building school!