3 tier loops complete

On January 20th I put the loop section in place for hopefully the last time. It's now been screwed into its location, and on that day it looked like this:



Some construction notes:

1. One of the challenges was figuring out the exact tangent that the return tracks would take leaving the loop. This required making cardboard mockups, drawing tracklines on those markups, then cutting wood to match. Even then, at every step in construction I put the mockups back in place to verify that it would all work together correctly. Some remnants of the mockups can be seen in this picture on the floor.
   
2. You can't see it very well in this picture, but after some tests I found a good solution for connecting separate pieces of the lauan plywood together. You can see this best on the left side of the picture on the top pier. I cut 4 long, narrow strips of lauan and used them to bridge the gap between the two pieces. Two pieces are used on each side of the track path, one above and one below the subroadbed. They are connnected with small #6 5/8" screws. The connection method was my standard process -- C-clamp the wood pieces together, drill pilot holes, put in the screws, then measure and test. In order to make this work the lauan plywood has to be cut wider than needed for just the track.
   
3. The 2x2 support piers for the lauan worked, but required tons of measuring, careful cutting, then adjusting. I chose 2x2 only because I wanted a broad surface to support the 5.2mm thick lauan plywood -- I'd never used lauan before and wasn't sure of it's stiffness. I also cut the lauan subroadbed using straight borders instead of curved because I anticipated possibly having to attach a vertical wood stabilizers to the sides of the lauan in order to make the surface stiff and level enough. It turned out that this wasn't necessary, and in fact this lauan would probably have maintained a level surface even if I used an simpler support technique, such as threaded bolts for piers and nuts/washers for support. The big advantage of the bolt/washer technique is that it makes it very easy to do minute adjustments of height on the fly. I will be trying that technique with the top tier bridge that is needed for this staging.