Today is momentous day, The Olympics started. Besides that! I began actual construction on the layout. I cut the wood for the four brackets that will be mounted on the back wall to support the rear part of the layout. The brackets are supported by a 2 X 2, with two 2 X 3 arms and a 2 X 2 angle brace. The main components are fastened together with 1/4" carriage bolts. The angle bracket to upright connection will be with Spax wood screws and gussets.
The end brackets will also have a horizontal sway brace facing outwards that will make the whole think more rigid. Once all the ply pieces are in place, that will also stiffen any horizontal motion. It's nice to have a good chop saw and I just added a big, DeWalt 18 Volt Li-ion, 1/2" hammer drill. This thing is a bruiser and has three modes and three speed settings. I needed to up the horsepower to handle the concrete drilling tasks AND handle the fastening of thousands of screws. That's a fact, it's over 1,000 fasteners to hold this thing together.
The bottom of each upright has large diameter carriage bolt feet. I epoxied "t" nuts into the bottom and then screw in the bolts with a lock nut halfway in. This gives me a lot of adjustment for uneven floors. This is the same scheme I used in building the existing part of the layout.
Here's the bracket fitted with the diagonal brace. Even though it's only a 2 X 2, when properly braced and having the load directly into the length, it's very strong. Kind of like building an airplane rather than a barn.
In the next couple of days I'll finish the assembly, break them apart to more easily mount the upright to the wall and then reassemble them in place. The uprights will be held on top with a 1/2" wedge bolt, and the bottom with a smaller (lighter) Tapcon. With a cantilevered bracket, the main load is on top, and through the angle bracket to the foot.